From 8e687c3cc432a821fd157d6d8691c572bbaf5db5 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Thu, 22 Jul 2021 17:15:07 +0200
Subject: [PATCH 01/24] Failing test cases

---
 .../java/org/apache/commons/lang3/StringUtilsTest.java   | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
index 2f6d9a706a8..bc718a954a5 100644
--- a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
@@ -1143,6 +1143,7 @@ public void testJoin_ArrayCharSeparator() {
         assertEquals("foo/2", StringUtils.join(MIXED_TYPE_LIST, '/', 0, 2));
         assertEquals("2", StringUtils.join(MIXED_TYPE_LIST, '/', 1, 2));
         assertEquals("", StringUtils.join(MIXED_TYPE_LIST, '/', 2, 1));
+        assertEquals("1,2", StringUtils.join(CHAR_PRIM_LIST, SEPARATOR));
     }
 
     @Test
@@ -1153,6 +1154,7 @@ public void testJoin_ArrayOfBytes() {
         assertNull(StringUtils.join((byte[]) null, SEPARATOR_CHAR, 0, 1));
         assertEquals(StringUtils.EMPTY, StringUtils.join(BYTE_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(BYTE_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
+        assertEquals("1,2", StringUtils.join(BYTE_PRIM_LIST, SEPARATOR));
     }
 
 
@@ -1166,6 +1168,7 @@ public void testJoin_ArrayOfBooleans() {
         assertNull(StringUtils.join((boolean[]) null, SEPARATOR_CHAR, 0, 1));
         assertEquals(StringUtils.EMPTY, StringUtils.join(ARRAY_FALSE_FALSE, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(ARRAY_FALSE_TRUE_FALSE, SEPARATOR_CHAR, 1, 0));
+        assertEquals("1,2", StringUtils.join(ARRAY_FALSE_TRUE_FALSE, SEPARATOR));
     }
 
     @Test
@@ -1176,6 +1179,7 @@ public void testJoin_ArrayOfChars() {
         assertNull(StringUtils.join((char[]) null, SEPARATOR_CHAR, 0, 1));
         assertEquals(StringUtils.EMPTY, StringUtils.join(CHAR_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(CHAR_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
+        assertEquals("1,2", StringUtils.join(CHAR_PRIM_LIST, SEPARATOR));
     }
 
     @Test
@@ -1186,6 +1190,7 @@ public void testJoin_ArrayOfDoubles() {
         assertNull(StringUtils.join((double[]) null, SEPARATOR_CHAR, 0, 1));
         assertEquals(StringUtils.EMPTY, StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
+        assertEquals("1,2", StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR));
     }
 
     @Test
@@ -1196,6 +1201,7 @@ public void testJoin_ArrayOfFloats() {
         assertNull(StringUtils.join((float[]) null, SEPARATOR_CHAR, 0, 1));
         assertEquals(StringUtils.EMPTY, StringUtils.join(FLOAT_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(FLOAT_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
+        assertEquals("1.0,2.0", StringUtils.join(FLOAT_PRIM_LIST, SEPARATOR));
     }
 
     @Test
@@ -1206,6 +1212,7 @@ public void testJoin_ArrayOfInts() {
         assertNull(StringUtils.join((int[]) null, SEPARATOR_CHAR, 0, 1));
         assertEquals(StringUtils.EMPTY, StringUtils.join(INT_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(INT_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
+        assertEquals("1;2", StringUtils.join(INT_PRIM_LIST, SEPARATOR_CHAR));
     }
 
     @Test
@@ -1216,6 +1223,7 @@ public void testJoin_ArrayOfLongs() {
         assertNull(StringUtils.join((long[]) null, SEPARATOR_CHAR, 0, 1));
         assertEquals(StringUtils.EMPTY, StringUtils.join(LONG_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(LONG_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
+        assertEquals("1,2", StringUtils.join(LONG_PRIM_LIST, SEPARATOR));
     }
 
     @Test
@@ -1226,6 +1234,7 @@ public void testJoin_ArrayOfShorts() {
         assertNull(StringUtils.join((short[]) null, SEPARATOR_CHAR, 0, 1));
         assertEquals(StringUtils.EMPTY, StringUtils.join(SHORT_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(SHORT_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
+        assertEquals("1,2", StringUtils.join(SHORT_PRIM_LIST, SEPARATOR));
     }
 
     @Test

From 79b47b8747baa945a2f07620c7cd3fdfad7ee127 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Thu, 22 Jul 2021 17:52:22 +0200
Subject: [PATCH 02/24] Fix for: long[]

---
 .../java/org/apache/commons/lang3/StringUtils.java   | 12 +++++++++++-
 .../org/apache/commons/lang3/StringUtilsTest.java    |  2 +-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index 5f22048ba0b..fc7aeb321d0 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -4593,13 +4593,17 @@ public static String join(final long[] array, final char separator) {
      * @since 3.2
      */
     public static String join(final long[] array, final char delimiter, final int startIndex, final int endIndex) {
+        return join(array, Character.toString(delimiter), startIndex, endIndex);
+    }
+
+    public static String join(final long[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
         }
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = newStringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4858,6 +4862,10 @@ public static <T> String join(final T... elements) {
         return join(elements, null);
     }
 
+    public static <T> String join(long[] elements, String separator) {
+        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+    }
+
     /**
      * <p>Joins the elements of the provided varargs into a
      * single String containing the provided elements.</p>
@@ -5520,6 +5528,8 @@ public static String mid(final String str, int pos, final int len) {
         return str.substring(pos, pos + len);
     }
 
+    // TODO: remove
+    @Deprecated
     private static StringJoiner newStringJoiner(final char delimiter) {
         return new StringJoiner(String.valueOf(delimiter));
     }
diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
index bc718a954a5..fd806873436 100644
--- a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
@@ -1143,7 +1143,7 @@ public void testJoin_ArrayCharSeparator() {
         assertEquals("foo/2", StringUtils.join(MIXED_TYPE_LIST, '/', 0, 2));
         assertEquals("2", StringUtils.join(MIXED_TYPE_LIST, '/', 1, 2));
         assertEquals("", StringUtils.join(MIXED_TYPE_LIST, '/', 2, 1));
-        assertEquals("1,2", StringUtils.join(CHAR_PRIM_LIST, SEPARATOR));
+        assertEquals("1;2", StringUtils.join(CHAR_PRIM_LIST, SEPARATOR_CHAR));
     }
 
     @Test

From 43a603e6ac8a84e42fde54e71078c5ce4788adbc Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Fri, 23 Jul 2021 18:28:31 +0200
Subject: [PATCH 03/24] Join: byte[] and boolean[]

---
 .../org/apache/commons/lang3/StringUtils.java | 47 +++++++++++++++++--
 .../apache/commons/lang3/StringUtilsTest.java |  2 +-
 2 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index fc7aeb321d0..bd2af548a1c 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -30,6 +30,10 @@
 import java.util.StringJoiner;
 import java.util.function.Supplier;
 import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+import java.util.stream.LongStream;
+import java.util.stream.Stream;
 
 import org.apache.commons.lang3.function.Suppliers;
 import org.apache.commons.lang3.function.ToBooleanBiFunction;
@@ -4603,13 +4607,40 @@ public static String join(final long[] array, final String delimiter, final int
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(delimiter);
-        for (int i = startIndex; i < endIndex; i++) {
-            joiner.add(String.valueOf(array[i]));
+
+        return join(LongStream.of(array).boxed().map(String::valueOf), delimiter, startIndex, endIndex);
+    }
+
+    public static String join(final byte[] array, final String delimiter, final int startIndex, final int endIndex) {
+        if (array == null) {
+            return null;
         }
-        return joiner.toString();
+        if (endIndex - startIndex <= 0) {
+            return EMPTY;
+        }
+
+        // Java Stream API does not provide ByteStream
+        return join(IntStream.range(0, array.length).map(idx -> array[idx]).boxed().map(String::valueOf), delimiter, startIndex, endIndex);
+    }
+
+    public static String join(final boolean[] array, final String delimiter, final int startIndex, final int endIndex) {
+        if (array == null) {
+            return null;
+        }
+        if (endIndex - startIndex <= 0) {
+            return EMPTY;
+        }
+
+        // Java Stream API does not provide BooleanStream
+        return join(IntStream.range(0, array.length).boxed().map(idx -> array[idx]).map(String::valueOf), delimiter, startIndex, endIndex);
     }
 
+    private static String join(Stream<String> elements, final String delimiter, final int startIndex, final int endIndex) {
+        return elements
+                .skip(startIndex)
+                .limit(endIndex)
+                .collect(Collectors.joining(delimiter));
+    }
     /**
      * <p>Joins the elements of the provided array into a single String
      * containing the provided list of elements.</p>
@@ -4866,6 +4897,14 @@ public static <T> String join(long[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
+    public static <T> String join(byte[] elements, String separator) {
+        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+    }
+
+    public static <T> String join(boolean[] elements, String separator) {
+        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+    }
+
     /**
      * <p>Joins the elements of the provided varargs into a
      * single String containing the provided elements.</p>
diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
index fd806873436..ce7e9288c3a 100644
--- a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
@@ -1168,7 +1168,7 @@ public void testJoin_ArrayOfBooleans() {
         assertNull(StringUtils.join((boolean[]) null, SEPARATOR_CHAR, 0, 1));
         assertEquals(StringUtils.EMPTY, StringUtils.join(ARRAY_FALSE_FALSE, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(ARRAY_FALSE_TRUE_FALSE, SEPARATOR_CHAR, 1, 0));
-        assertEquals("1,2", StringUtils.join(ARRAY_FALSE_TRUE_FALSE, SEPARATOR));
+        assertEquals("false,true,false", StringUtils.join(ARRAY_FALSE_TRUE_FALSE, SEPARATOR));
     }
 
     @Test

From 5ecaa6653a9f37786a5de6debdccac3ed1eb1a12 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Wed, 4 Aug 2021 08:56:26 +0200
Subject: [PATCH 04/24] Join: char[]

---
 .../org/apache/commons/lang3/StringUtils.java    | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index bd2af548a1c..c4780de1451 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -4611,6 +4611,18 @@ public static String join(final long[] array, final String delimiter, final int
         return join(LongStream.of(array).boxed().map(String::valueOf), delimiter, startIndex, endIndex);
     }
 
+    public static String join(final char[] array, final String delimiter, final int startIndex, final int endIndex) {
+        if (array == null) {
+            return null;
+        }
+        if (endIndex - startIndex <= 0) {
+            return EMPTY;
+        }
+
+        // Java Stream API does not provide CharStream
+        return join(IntStream.range(0, array.length).mapToObj(idx -> String.valueOf(array[idx])), delimiter, startIndex, endIndex);
+    }
+
     public static String join(final byte[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
@@ -4893,6 +4905,10 @@ public static <T> String join(final T... elements) {
         return join(elements, null);
     }
 
+    public static <T> String join(char[] elements, String separator) {
+        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+    }
+
     public static <T> String join(long[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }

From 41620964d56ed39d0d3388448177f09e5dec38b8 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Wed, 4 Aug 2021 19:44:38 +0200
Subject: [PATCH 05/24] Join: double[]

---
 .../org/apache/commons/lang3/StringUtils.java   | 17 +++++++++++++++++
 .../apache/commons/lang3/StringUtilsTest.java   |  2 +-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index c4780de1451..f72ee9a33e8 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -31,6 +31,7 @@
 import java.util.function.Supplier;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
+import java.util.stream.DoubleStream;
 import java.util.stream.IntStream;
 import java.util.stream.LongStream;
 import java.util.stream.Stream;
@@ -4600,6 +4601,18 @@ public static String join(final long[] array, final char delimiter, final int st
         return join(array, Character.toString(delimiter), startIndex, endIndex);
     }
 
+
+    public static String join(final double[] array, final String delimiter, final int startIndex, final int endIndex) {
+        if (array == null) {
+            return null;
+        }
+        if (endIndex - startIndex <= 0) {
+            return EMPTY;
+        }
+
+        return join(DoubleStream.of(array).boxed().map(String::valueOf), delimiter, startIndex, endIndex);
+    }
+
     public static String join(final long[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
@@ -4909,6 +4922,10 @@ public static <T> String join(char[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
+    public static <T> String join(double[] elements, String separator) {
+        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+    }
+
     public static <T> String join(long[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
index ce7e9288c3a..f50cda119b6 100644
--- a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
@@ -1190,7 +1190,7 @@ public void testJoin_ArrayOfDoubles() {
         assertNull(StringUtils.join((double[]) null, SEPARATOR_CHAR, 0, 1));
         assertEquals(StringUtils.EMPTY, StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
-        assertEquals("1,2", StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR));
+        assertEquals("1.0;2.0", StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR_CHAR));
     }
 
     @Test

From 05a4a17891e58482a49c21c76d3963baffd50c88 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Wed, 4 Aug 2021 19:55:44 +0200
Subject: [PATCH 06/24] Join: short[] and float[]

---
 .../org/apache/commons/lang3/StringUtils.java | 31 +++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index f72ee9a33e8..7d6b0975aeb 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -4601,6 +4601,29 @@ public static String join(final long[] array, final char delimiter, final int st
         return join(array, Character.toString(delimiter), startIndex, endIndex);
     }
 
+    public static String join(final short[] array, final String delimiter, final int startIndex, final int endIndex) {
+        if (array == null) {
+            return null;
+        }
+        if (endIndex - startIndex <= 0) {
+            return EMPTY;
+        }
+
+        // Java Stream API does not provide ShortStream
+        return join(IntStream.range(0, array.length).mapToObj(idx -> String.valueOf(array[idx])), delimiter, startIndex, endIndex);
+    }
+
+    public static String join(final float[] array, final String delimiter, final int startIndex, final int endIndex) {
+        if (array == null) {
+            return null;
+        }
+        if (endIndex - startIndex <= 0) {
+            return EMPTY;
+        }
+
+        // Java Stream API does not provide FloatStream
+        return join(IntStream.range(0, array.length).mapToObj(idx -> String.valueOf(array[idx])), delimiter, startIndex, endIndex);
+    }
 
     public static String join(final double[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
@@ -4922,6 +4945,14 @@ public static <T> String join(char[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
+    public static <T> String join(short[] elements, String separator) {
+        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+    }
+
+    public static <T> String join(float[] elements, String separator) {
+        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+    }
+
     public static <T> String join(double[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }

From e83115da9f37086d7d9522aeceb594ed7b202d3c Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Wed, 4 Aug 2021 20:21:33 +0200
Subject: [PATCH 07/24] Code cleanup

---
 .../org/apache/commons/lang3/StringUtils.java | 130 +++++-------------
 .../apache/commons/lang3/StringUtilsTest.java |   2 +-
 2 files changed, 36 insertions(+), 96 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index 7d6b0975aeb..dc6fda4dc6c 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -3927,13 +3927,17 @@ public static String join(final boolean[] array, final char delimiter) {
      * @since 3.12.0
      */
     public static String join(final boolean[] array, final char delimiter, final int startIndex, final int endIndex) {
+        return join(array, String.valueOf(delimiter), startIndex, endIndex);
+    }
+
+    public static String join(final boolean[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
         }
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = newStringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4004,13 +4008,17 @@ public static String join(final byte[] array, final char delimiter) {
      * @since 3.2
      */
     public static String join(final byte[] array, final char delimiter, final int startIndex, final int endIndex) {
+        return join(array, String.valueOf(delimiter), startIndex, endIndex);
+    }
+
+    public static String join(final byte[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
         }
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = newStringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4081,13 +4089,17 @@ public static String join(final char[] array, final char delimiter) {
      * @since 3.2
      */
     public static String join(final char[] array, final char delimiter, final int startIndex, final int endIndex) {
+        return join(array, String.valueOf(delimiter), startIndex, endIndex);
+    }
+
+    public static String join(final char[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
         }
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = newStringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4158,13 +4170,17 @@ public static String join(final double[] array, final char delimiter) {
      * @since 3.2
      */
     public static String join(final double[] array, final char delimiter, final int startIndex, final int endIndex) {
+        return join(array, String.valueOf(delimiter), startIndex, endIndex);
+    }
+
+    public static String join(final double[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
         }
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = newStringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4235,13 +4251,16 @@ public static String join(final float[] array, final char delimiter) {
      * @since 3.2
      */
     public static String join(final float[] array, final char delimiter, final int startIndex, final int endIndex) {
+        return join(array, String.valueOf(delimiter), startIndex, endIndex);
+    }
+    public static String join(final float[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
         }
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = newStringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4312,13 +4331,17 @@ public static String join(final int[] array, final char separator) {
      * @since 3.2
      */
     public static String join(final int[] array, final char delimiter, final int startIndex, final int endIndex) {
+        return join(array, String.valueOf(delimiter), startIndex, endIndex);
+    }
+
+    public static String join(final int[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
         }
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = newStringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4601,41 +4624,6 @@ public static String join(final long[] array, final char delimiter, final int st
         return join(array, Character.toString(delimiter), startIndex, endIndex);
     }
 
-    public static String join(final short[] array, final String delimiter, final int startIndex, final int endIndex) {
-        if (array == null) {
-            return null;
-        }
-        if (endIndex - startIndex <= 0) {
-            return EMPTY;
-        }
-
-        // Java Stream API does not provide ShortStream
-        return join(IntStream.range(0, array.length).mapToObj(idx -> String.valueOf(array[idx])), delimiter, startIndex, endIndex);
-    }
-
-    public static String join(final float[] array, final String delimiter, final int startIndex, final int endIndex) {
-        if (array == null) {
-            return null;
-        }
-        if (endIndex - startIndex <= 0) {
-            return EMPTY;
-        }
-
-        // Java Stream API does not provide FloatStream
-        return join(IntStream.range(0, array.length).mapToObj(idx -> String.valueOf(array[idx])), delimiter, startIndex, endIndex);
-    }
-
-    public static String join(final double[] array, final String delimiter, final int startIndex, final int endIndex) {
-        if (array == null) {
-            return null;
-        }
-        if (endIndex - startIndex <= 0) {
-            return EMPTY;
-        }
-
-        return join(DoubleStream.of(array).boxed().map(String::valueOf), delimiter, startIndex, endIndex);
-    }
-
     public static String join(final long[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
@@ -4647,42 +4635,6 @@ public static String join(final long[] array, final String delimiter, final int
         return join(LongStream.of(array).boxed().map(String::valueOf), delimiter, startIndex, endIndex);
     }
 
-    public static String join(final char[] array, final String delimiter, final int startIndex, final int endIndex) {
-        if (array == null) {
-            return null;
-        }
-        if (endIndex - startIndex <= 0) {
-            return EMPTY;
-        }
-
-        // Java Stream API does not provide CharStream
-        return join(IntStream.range(0, array.length).mapToObj(idx -> String.valueOf(array[idx])), delimiter, startIndex, endIndex);
-    }
-
-    public static String join(final byte[] array, final String delimiter, final int startIndex, final int endIndex) {
-        if (array == null) {
-            return null;
-        }
-        if (endIndex - startIndex <= 0) {
-            return EMPTY;
-        }
-
-        // Java Stream API does not provide ByteStream
-        return join(IntStream.range(0, array.length).map(idx -> array[idx]).boxed().map(String::valueOf), delimiter, startIndex, endIndex);
-    }
-
-    public static String join(final boolean[] array, final String delimiter, final int startIndex, final int endIndex) {
-        if (array == null) {
-            return null;
-        }
-        if (endIndex - startIndex <= 0) {
-            return EMPTY;
-        }
-
-        // Java Stream API does not provide BooleanStream
-        return join(IntStream.range(0, array.length).boxed().map(idx -> array[idx]).map(String::valueOf), delimiter, startIndex, endIndex);
-    }
-
     private static String join(Stream<String> elements, final String delimiter, final int startIndex, final int endIndex) {
         return elements
                 .skip(startIndex)
@@ -4745,17 +4697,7 @@ public static String join(final Object[] array, final char delimiter) {
      * @since 2.0
      */
     public static String join(final Object[] array, final char delimiter, final int startIndex, final int endIndex) {
-        if (array == null) {
-            return null;
-        }
-        if (endIndex - startIndex <= 0) {
-            return EMPTY;
-        }
-        final StringJoiner joiner = newStringJoiner(delimiter);
-        for (int i = startIndex; i < endIndex; i++) {
-            joiner.add(toStringOrEmpty(array[i]));
-        }
-        return joiner.toString();
+        return join(array, String.valueOf(delimiter), startIndex, endIndex);
     }
 
     /**
@@ -4901,13 +4843,17 @@ public static String join(final short[] array, final char delimiter) {
      * @since 3.2
      */
     public static String join(final short[] array, final char delimiter, final int startIndex, final int endIndex) {
+        return join(array, String.valueOf(delimiter), startIndex, endIndex);
+    }
+
+    public static String join(final short[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
         }
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = newStringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -5631,12 +5577,6 @@ public static String mid(final String str, int pos, final int len) {
         return str.substring(pos, pos + len);
     }
 
-    // TODO: remove
-    @Deprecated
-    private static StringJoiner newStringJoiner(final char delimiter) {
-        return new StringJoiner(String.valueOf(delimiter));
-    }
-
     /**
      * <p>
      * Similar to <a
diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
index f50cda119b6..bc5fd3b1332 100644
--- a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
@@ -1190,7 +1190,7 @@ public void testJoin_ArrayOfDoubles() {
         assertNull(StringUtils.join((double[]) null, SEPARATOR_CHAR, 0, 1));
         assertEquals(StringUtils.EMPTY, StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
-        assertEquals("1.0;2.0", StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR_CHAR));
+        assertEquals("1.0,2.0", StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR));
     }
 
     @Test

From 171924205550647dc518db3c7d2ffe5a5009b007 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Wed, 4 Aug 2021 20:28:09 +0200
Subject: [PATCH 08/24] Removed disabled test

---
 src/main/java/org/apache/commons/lang3/StringUtils.java  | 6 ++++--
 .../java/org/apache/commons/lang3/StringUtilsTest.java   | 9 ---------
 2 files changed, 4 insertions(+), 11 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index dc6fda4dc6c..c8f20425675 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -31,8 +31,6 @@
 import java.util.function.Supplier;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
-import java.util.stream.DoubleStream;
-import java.util.stream.IntStream;
 import java.util.stream.LongStream;
 import java.util.stream.Stream;
 
@@ -4887,6 +4885,10 @@ public static <T> String join(final T... elements) {
         return join(elements, null);
     }
 
+    public static <T> String join(int[] elements, String separator) {
+        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+    }
+
     public static <T> String join(char[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
index bc5fd3b1332..a391e16030d 100644
--- a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
@@ -1364,15 +1364,6 @@ public void testJoin_Objectarray() {
         assertEquals("foo2", StringUtils.join(MIXED_TYPE_LIST));
     }
 
-    @Disabled
-    @Test
-    public void testLang1593() {
-        final int[] arr = {1, 2, 3, 4, 5, 6, 7};
-        final String expected = StringUtils.join(arr, '-');
-        final String actual = StringUtils.join(arr, "-");
-        assertEquals(expected, actual);
-    }
-
     @Test
     public void testJoin_Objects() {
         assertEquals("abc", StringUtils.join("a", "b", "c"));

From 8fc19c9f9e90e34590c6098610713f75ff25cc7d Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Wed, 4 Aug 2021 20:49:21 +0200
Subject: [PATCH 09/24] Code cleanup - method order

---
 .../org/apache/commons/lang3/StringUtils.java    | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index c8f20425675..00f4336c572 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -4885,35 +4885,35 @@ public static <T> String join(final T... elements) {
         return join(elements, null);
     }
 
-    public static <T> String join(int[] elements, String separator) {
+    public static <T> String join(byte[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
-    public static <T> String join(char[] elements, String separator) {
+    public static <T> String join(boolean[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
-    public static <T> String join(short[] elements, String separator) {
+    public static <T> String join(char[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
-    public static <T> String join(float[] elements, String separator) {
+    public static <T> String join(double[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
-    public static <T> String join(double[] elements, String separator) {
+    public static <T> String join(float[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
-    public static <T> String join(long[] elements, String separator) {
+    public static <T> String join(int[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
-    public static <T> String join(byte[] elements, String separator) {
+    public static <T> String join(long[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
-    public static <T> String join(boolean[] elements, String separator) {
+    public static <T> String join(short[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 

From b0f5bd3572c1f1c678e95a8a6e7111802eec7955 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Wed, 4 Aug 2021 20:52:53 +0200
Subject: [PATCH 10/24] Removed import of Streams.* and added missing join
 method for long[]

---
 .../org/apache/commons/lang3/StringUtils.java | 34 ++++++++-----------
 1 file changed, 14 insertions(+), 20 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index 00f4336c572..b95377ee1ba 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -30,9 +30,6 @@
 import java.util.StringJoiner;
 import java.util.function.Supplier;
 import java.util.regex.Pattern;
-import java.util.stream.Collectors;
-import java.util.stream.LongStream;
-import java.util.stream.Stream;
 
 import org.apache.commons.lang3.function.Suppliers;
 import org.apache.commons.lang3.function.ToBooleanBiFunction;
@@ -4622,23 +4619,6 @@ public static String join(final long[] array, final char delimiter, final int st
         return join(array, Character.toString(delimiter), startIndex, endIndex);
     }
 
-    public static String join(final long[] array, final String delimiter, final int startIndex, final int endIndex) {
-        if (array == null) {
-            return null;
-        }
-        if (endIndex - startIndex <= 0) {
-            return EMPTY;
-        }
-
-        return join(LongStream.of(array).boxed().map(String::valueOf), delimiter, startIndex, endIndex);
-    }
-
-    private static String join(Stream<String> elements, final String delimiter, final int startIndex, final int endIndex) {
-        return elements
-                .skip(startIndex)
-                .limit(endIndex)
-                .collect(Collectors.joining(delimiter));
-    }
     /**
      * <p>Joins the elements of the provided array into a single String
      * containing the provided list of elements.</p>
@@ -4698,6 +4678,20 @@ public static String join(final Object[] array, final char delimiter, final int
         return join(array, String.valueOf(delimiter), startIndex, endIndex);
     }
 
+    public static String join(final long[] array, final String delimiter, final int startIndex, final int endIndex) {
+        if (array == null) {
+            return null;
+        }
+        if (endIndex - startIndex <= 0) {
+            return EMPTY;
+        }
+        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
+        for (int i = startIndex; i < endIndex; i++) {
+            joiner.add(toStringOrEmpty(array[i]));
+        }
+        return joiner.toString();
+    }
+
     /**
      * <p>Joins the elements of the provided array into a single String
      * containing the provided list of elements.</p>

From d106a3f28728455ff703f5eeda4d7c1db196954c Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Wed, 4 Aug 2021 20:54:31 +0200
Subject: [PATCH 11/24] Removed generic from method signatures

---
 .../org/apache/commons/lang3/StringUtils.java    | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index b95377ee1ba..b8233a3aef4 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -4879,35 +4879,35 @@ public static <T> String join(final T... elements) {
         return join(elements, null);
     }
 
-    public static <T> String join(byte[] elements, String separator) {
+    public static String join(byte[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
-    public static <T> String join(boolean[] elements, String separator) {
+    public static String join(boolean[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
-    public static <T> String join(char[] elements, String separator) {
+    public static String join(char[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
-    public static <T> String join(double[] elements, String separator) {
+    public static String join(double[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
-    public static <T> String join(float[] elements, String separator) {
+    public static String join(float[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
-    public static <T> String join(int[] elements, String separator) {
+    public static String join(int[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
-    public static <T> String join(long[] elements, String separator) {
+    public static String join(long[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 
-    public static <T> String join(short[] elements, String separator) {
+    public static String join(short[] elements, String separator) {
         return (elements == null) ? null  : join(elements, separator, 0, elements.length);
     }
 

From aa208fd24ec1c7cc5a9396d9dd2c002f9f1a6777 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Wed, 4 Aug 2021 20:57:53 +0200
Subject: [PATCH 12/24] Code cleanup

---
 .../org/apache/commons/lang3/StringUtils.java    | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index b8233a3aef4..a27270b307f 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -4880,35 +4880,35 @@ public static <T> String join(final T... elements) {
     }
 
     public static String join(byte[] elements, String separator) {
-        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+        return (elements == null) ? null : join(elements, separator, 0, elements.length);
     }
 
     public static String join(boolean[] elements, String separator) {
-        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+        return (elements == null) ? null : join(elements, separator, 0, elements.length);
     }
 
     public static String join(char[] elements, String separator) {
-        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+        return (elements == null) ? null : join(elements, separator, 0, elements.length);
     }
 
     public static String join(double[] elements, String separator) {
-        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+        return (elements == null) ? null : join(elements, separator, 0, elements.length);
     }
 
     public static String join(float[] elements, String separator) {
-        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+        return (elements == null) ? null : join(elements, separator, 0, elements.length);
     }
 
     public static String join(int[] elements, String separator) {
-        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+        return (elements == null) ? null : join(elements, separator, 0, elements.length);
     }
 
     public static String join(long[] elements, String separator) {
-        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+        return (elements == null) ? null : join(elements, separator, 0, elements.length);
     }
 
     public static String join(short[] elements, String separator) {
-        return (elements == null) ? null  : join(elements, separator, 0, elements.length);
+        return (elements == null) ? null : join(elements, separator, 0, elements.length);
     }
 
     /**

From b7a7d5118fb1b99f261abd116c913241004b667e Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Wed, 4 Aug 2021 21:03:03 +0200
Subject: [PATCH 13/24] Removed toStringOrEmpty

---
 src/main/java/org/apache/commons/lang3/StringUtils.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index a27270b307f..630235acfff 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -4685,7 +4685,7 @@ public static String join(final long[] array, final String delimiter, final int
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
+        final StringJoiner joiner = new StringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(toStringOrEmpty(array[i]));
         }

From ae3325dd98a9786083f57da5abf0c2bed4e2db57 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Wed, 4 Aug 2021 21:13:06 +0200
Subject: [PATCH 14/24] Test cases for null separator

---
 .../org/apache/commons/lang3/StringUtils.java | 46 +++++++++++++++----
 .../apache/commons/lang3/StringUtilsTest.java | 10 +++-
 2 files changed, 47 insertions(+), 9 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index 630235acfff..d4ab30f4910 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -3925,6 +3925,36 @@ public static String join(final boolean[] array, final char delimiter, final int
         return join(array, String.valueOf(delimiter), startIndex, endIndex);
     }
 
+    /**
+     * <p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
+     * </p>
+     *
+     * <p>
+     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.
+     * </p>
+     *
+     * <pre>
+     * StringUtils.join(null, *)                   = null
+     * StringUtils.join([], *)                     = ""
+     * StringUtils.join([null], *)                 = ""
+     * StringUtils.join([true, false, true], ';')  = "true;false;true"
+     * </pre>
+     *
+     * @param array
+     *            the array of values to join together, may be null
+     * @param delimiter
+     *            the separator String to use
+     * @param startIndex
+     *            the first index to start joining from. It is an error to pass in a start index past the end of the
+     *            array
+     * @param endIndex
+     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
+     *            the array
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
     public static String join(final boolean[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
@@ -3932,7 +3962,7 @@ public static String join(final boolean[] array, final String delimiter, final i
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4013,7 +4043,7 @@ public static String join(final byte[] array, final String delimiter, final int
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4094,7 +4124,7 @@ public static String join(final char[] array, final String delimiter, final int
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4175,7 +4205,7 @@ public static String join(final double[] array, final String delimiter, final in
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4255,7 +4285,7 @@ public static String join(final float[] array, final String delimiter, final int
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4336,7 +4366,7 @@ public static String join(final int[] array, final String delimiter, final int s
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4685,7 +4715,7 @@ public static String join(final long[] array, final String delimiter, final int
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(toStringOrEmpty(array[i]));
         }
@@ -4845,7 +4875,7 @@ public static String join(final short[] array, final String delimiter, final int
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(delimiter);
+        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
index a391e16030d..6ec9e8022fb 100644
--- a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
@@ -1155,6 +1155,7 @@ public void testJoin_ArrayOfBytes() {
         assertEquals(StringUtils.EMPTY, StringUtils.join(BYTE_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(BYTE_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
         assertEquals("1,2", StringUtils.join(BYTE_PRIM_LIST, SEPARATOR));
+        assertEquals("12", StringUtils.join(BYTE_PRIM_LIST, null));
     }
 
 
@@ -1169,6 +1170,7 @@ public void testJoin_ArrayOfBooleans() {
         assertEquals(StringUtils.EMPTY, StringUtils.join(ARRAY_FALSE_FALSE, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(ARRAY_FALSE_TRUE_FALSE, SEPARATOR_CHAR, 1, 0));
         assertEquals("false,true,false", StringUtils.join(ARRAY_FALSE_TRUE_FALSE, SEPARATOR));
+        assertEquals("falsetruefalse", StringUtils.join(ARRAY_FALSE_TRUE_FALSE, null));
     }
 
     @Test
@@ -1180,6 +1182,7 @@ public void testJoin_ArrayOfChars() {
         assertEquals(StringUtils.EMPTY, StringUtils.join(CHAR_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(CHAR_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
         assertEquals("1,2", StringUtils.join(CHAR_PRIM_LIST, SEPARATOR));
+        assertEquals("12", StringUtils.join(CHAR_PRIM_LIST, null));
     }
 
     @Test
@@ -1191,6 +1194,7 @@ public void testJoin_ArrayOfDoubles() {
         assertEquals(StringUtils.EMPTY, StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
         assertEquals("1.0,2.0", StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR));
+        assertEquals("1.02.0", StringUtils.join(DOUBLE_PRIM_LIST, null));
     }
 
     @Test
@@ -1202,6 +1206,7 @@ public void testJoin_ArrayOfFloats() {
         assertEquals(StringUtils.EMPTY, StringUtils.join(FLOAT_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(FLOAT_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
         assertEquals("1.0,2.0", StringUtils.join(FLOAT_PRIM_LIST, SEPARATOR));
+        assertEquals("1.02.0", StringUtils.join(FLOAT_PRIM_LIST, null));
     }
 
     @Test
@@ -1212,7 +1217,8 @@ public void testJoin_ArrayOfInts() {
         assertNull(StringUtils.join((int[]) null, SEPARATOR_CHAR, 0, 1));
         assertEquals(StringUtils.EMPTY, StringUtils.join(INT_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(INT_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
-        assertEquals("1;2", StringUtils.join(INT_PRIM_LIST, SEPARATOR_CHAR));
+        assertEquals("1,2", StringUtils.join(INT_PRIM_LIST, SEPARATOR));
+        assertEquals("12", StringUtils.join(INT_PRIM_LIST, null));
     }
 
     @Test
@@ -1224,6 +1230,7 @@ public void testJoin_ArrayOfLongs() {
         assertEquals(StringUtils.EMPTY, StringUtils.join(LONG_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(LONG_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
         assertEquals("1,2", StringUtils.join(LONG_PRIM_LIST, SEPARATOR));
+        assertEquals("12", StringUtils.join(LONG_PRIM_LIST, null));
     }
 
     @Test
@@ -1235,6 +1242,7 @@ public void testJoin_ArrayOfShorts() {
         assertEquals(StringUtils.EMPTY, StringUtils.join(SHORT_PRIM_LIST, SEPARATOR_CHAR, 0, 0));
         assertEquals(StringUtils.EMPTY, StringUtils.join(SHORT_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
         assertEquals("1,2", StringUtils.join(SHORT_PRIM_LIST, SEPARATOR));
+        assertEquals("12", StringUtils.join(SHORT_PRIM_LIST, null));
     }
 
     @Test

From d23593550bb8858c0bd12daa421bb5a3bf510552 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Wed, 4 Aug 2021 21:24:07 +0200
Subject: [PATCH 15/24] Test case for join char[] with null separator

---
 src/test/java/org/apache/commons/lang3/StringUtilsTest.java | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
index 6ec9e8022fb..6dfa424a79d 100644
--- a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
@@ -1143,7 +1143,8 @@ public void testJoin_ArrayCharSeparator() {
         assertEquals("foo/2", StringUtils.join(MIXED_TYPE_LIST, '/', 0, 2));
         assertEquals("2", StringUtils.join(MIXED_TYPE_LIST, '/', 1, 2));
         assertEquals("", StringUtils.join(MIXED_TYPE_LIST, '/', 2, 1));
-        assertEquals("1;2", StringUtils.join(CHAR_PRIM_LIST, SEPARATOR_CHAR));
+        assertEquals("1,2", StringUtils.join(CHAR_PRIM_LIST, SEPARATOR));
+        assertEquals("12", StringUtils.join(CHAR_PRIM_LIST, null));
     }
 
     @Test

From 7d53cfa843d994856b67bf5d062b32a709fe42a0 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Wed, 4 Aug 2021 21:59:21 +0200
Subject: [PATCH 16/24] JavaDoc

---
 .../org/apache/commons/lang3/StringUtils.java | 156 ++++++++++++++++++
 1 file changed, 156 insertions(+)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index d4ab30f4910..9732d842bc0 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -4036,6 +4036,37 @@ public static String join(final byte[] array, final char delimiter, final int st
         return join(array, String.valueOf(delimiter), startIndex, endIndex);
     }
 
+    /**
+     * <p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
+     * </p>
+     *
+     * <p>
+     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.
+     * </p>
+     *
+     * <pre>
+     * StringUtils.join(null, *)               = null
+     * StringUtils.join([], *)                 = ""
+     * StringUtils.join([null], *)             = ""
+     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
+     * StringUtils.join([1, 2, 3], null) = "123"
+     * </pre>
+     *
+     * @param array
+     *            the array of values to join together, may be null
+     * @param delimiter
+     *            the separator String to use
+     * @param startIndex
+     *            the first index to start joining from. It is an error to pass in a start index past the end of the
+     *            array
+     * @param endIndex
+     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
+     *            the array
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
     public static String join(final byte[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
@@ -4117,6 +4148,37 @@ public static String join(final char[] array, final char delimiter, final int st
         return join(array, String.valueOf(delimiter), startIndex, endIndex);
     }
 
+    /**
+     * <p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
+     * </p>
+     *
+     * <p>
+     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.
+     * </p>
+     *
+     * <pre>
+     * StringUtils.join(null, *)               = null
+     * StringUtils.join([], *)                 = ""
+     * StringUtils.join([null], *)             = ""
+     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
+     * StringUtils.join([1, 2, 3], null) = "123"
+     * </pre>
+     *
+     * @param array
+     *            the array of values to join together, may be null
+     * @param delimiter
+     *            the separator String to use
+     * @param startIndex
+     *            the first index to start joining from. It is an error to pass in a start index past the end of the
+     *            array
+     * @param endIndex
+     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
+     *            the array
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
     public static String join(final char[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
@@ -4198,6 +4260,37 @@ public static String join(final double[] array, final char delimiter, final int
         return join(array, String.valueOf(delimiter), startIndex, endIndex);
     }
 
+    /**
+     * <p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
+     * </p>
+     *
+     * <p>
+     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.
+     * </p>
+     *
+     * <pre>
+     * StringUtils.join(null, *)               = null
+     * StringUtils.join([], *)                 = ""
+     * StringUtils.join([null], *)             = ""
+     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
+     * StringUtils.join([1, 2, 3], null) = "123"
+     * </pre>
+     *
+     * @param array
+     *            the array of values to join together, may be null
+     * @param delimiter
+     *            the separator String to use
+     * @param startIndex
+     *            the first index to start joining from. It is an error to pass in a start index past the end of the
+     *            array
+     * @param endIndex
+     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
+     *            the array
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
     public static String join(final double[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
@@ -4278,6 +4371,38 @@ public static String join(final float[] array, final char delimiter) {
     public static String join(final float[] array, final char delimiter, final int startIndex, final int endIndex) {
         return join(array, String.valueOf(delimiter), startIndex, endIndex);
     }
+
+    /**
+     * <p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
+     * </p>
+     *
+     * <p>
+     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.
+     * </p>
+     *
+     * <pre>
+     * StringUtils.join(null, *)               = null
+     * StringUtils.join([], *)                 = ""
+     * StringUtils.join([null], *)             = ""
+     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
+     * StringUtils.join([1, 2, 3], null) = "123"
+     * </pre>
+     *
+     * @param array
+     *            the array of values to join together, may be null
+     * @param delimiter
+     *            the separator String to use
+     * @param startIndex
+     *            the first index to start joining from. It is an error to pass in a start index past the end of the
+     *            array
+     * @param endIndex
+     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
+     *            the array
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
     public static String join(final float[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;
@@ -4359,6 +4484,37 @@ public static String join(final int[] array, final char delimiter, final int sta
         return join(array, String.valueOf(delimiter), startIndex, endIndex);
     }
 
+    /**
+     * <p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
+     * </p>
+     *
+     * <p>
+     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.
+     * </p>
+     *
+     * <pre>
+     * StringUtils.join(null, *)               = null
+     * StringUtils.join([], *)                 = ""
+     * StringUtils.join([null], *)             = ""
+     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
+     * StringUtils.join([1, 2, 3], null) = "123"
+     * </pre>
+     *
+     * @param array
+     *            the array of values to join together, may be null
+     * @param delimiter
+     *            the separator String to use
+     * @param startIndex
+     *            the first index to start joining from. It is an error to pass in a start index past the end of the
+     *            array
+     * @param endIndex
+     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
+     *            the array
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
     public static String join(final int[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;

From feee78703e1e677beb68d7434607d065fe857953 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Wed, 4 Aug 2021 22:03:06 +0200
Subject: [PATCH 17/24] JavaDoc

---
 .../org/apache/commons/lang3/StringUtils.java | 90 ++++++++++++++++---
 1 file changed, 76 insertions(+), 14 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index 9732d842bc0..83decbbe975 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -4805,6 +4805,51 @@ public static String join(final long[] array, final char delimiter, final int st
         return join(array, Character.toString(delimiter), startIndex, endIndex);
     }
 
+    /**
+     * <p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
+     * </p>
+     *
+     * <p>
+     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.
+     * </p>
+     *
+     * <pre>
+     * StringUtils.join(null, *)               = null
+     * StringUtils.join([], *)                 = ""
+     * StringUtils.join([null], *)             = ""
+     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
+     * StringUtils.join([1, 2, 3], null) = "123"
+     * </pre>
+     *
+     * @param array
+     *            the array of values to join together, may be null
+     * @param delimiter
+     *            the separator String to use
+     * @param startIndex
+     *            the first index to start joining from. It is an error to pass in a start index past the end of the
+     *            array
+     * @param endIndex
+     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
+     *            the array
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
+    public static String join(final long[] array, final String delimiter, final int startIndex, final int endIndex) {
+        if (array == null) {
+            return null;
+        }
+        if (endIndex - startIndex <= 0) {
+            return EMPTY;
+        }
+        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
+        for (int i = startIndex; i < endIndex; i++) {
+            joiner.add(toStringOrEmpty(array[i]));
+        }
+        return joiner.toString();
+    }
+
     /**
      * <p>Joins the elements of the provided array into a single String
      * containing the provided list of elements.</p>
@@ -4864,20 +4909,6 @@ public static String join(final Object[] array, final char delimiter, final int
         return join(array, String.valueOf(delimiter), startIndex, endIndex);
     }
 
-    public static String join(final long[] array, final String delimiter, final int startIndex, final int endIndex) {
-        if (array == null) {
-            return null;
-        }
-        if (endIndex - startIndex <= 0) {
-            return EMPTY;
-        }
-        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
-        for (int i = startIndex; i < endIndex; i++) {
-            joiner.add(toStringOrEmpty(array[i]));
-        }
-        return joiner.toString();
-    }
-
     /**
      * <p>Joins the elements of the provided array into a single String
      * containing the provided list of elements.</p>
@@ -5024,6 +5055,37 @@ public static String join(final short[] array, final char delimiter, final int s
         return join(array, String.valueOf(delimiter), startIndex, endIndex);
     }
 
+    /**
+     * <p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
+     * </p>
+     *
+     * <p>
+     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.
+     * </p>
+     *
+     * <pre>
+     * StringUtils.join(null, *)               = null
+     * StringUtils.join([], *)                 = ""
+     * StringUtils.join([null], *)             = ""
+     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
+     * StringUtils.join([1, 2, 3], null) = "123"
+     * </pre>
+     *
+     * @param array
+     *            the array of values to join together, may be null
+     * @param delimiter
+     *            the separator String to use
+     * @param startIndex
+     *            the first index to start joining from. It is an error to pass in a start index past the end of the
+     *            array
+     * @param endIndex
+     *            the index to stop joining from (exclusive). It is an error to pass in an end index past the end of
+     *            the array
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
     public static String join(final short[] array, final String delimiter, final int startIndex, final int endIndex) {
         if (array == null) {
             return null;

From ed64d9ca588414e1aa5bca026d41a1775e39c0d2 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Wed, 4 Aug 2021 22:15:57 +0200
Subject: [PATCH 18/24] Fix: removed unused import

---
 src/test/java/org/apache/commons/lang3/StringUtilsTest.java | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
index 6dfa424a79d..64d5342bc4b 100644
--- a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
@@ -44,7 +44,6 @@
 
 import org.apache.commons.lang3.mutable.MutableInt;
 import org.apache.commons.lang3.text.WordUtils;
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
 /**

From b7693a3cb8e0a8824ab73b80081ce9947e629d75 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Thu, 5 Aug 2021 18:40:48 +0200
Subject: [PATCH 19/24] Code review fix - remove useless parentheses

---
 .../org/apache/commons/lang3/StringUtils.java | 32 +++++++++----------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index 83decbbe975..e0ce1738e69 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -5127,36 +5127,36 @@ public static <T> String join(final T... elements) {
         return join(elements, null);
     }
 
-    public static String join(byte[] elements, String separator) {
-        return (elements == null) ? null : join(elements, separator, 0, elements.length);
+    public static String join(final byte[] elements, String separator) {
+        return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 
-    public static String join(boolean[] elements, String separator) {
-        return (elements == null) ? null : join(elements, separator, 0, elements.length);
+    public static String join(final boolean[] elements, String separator) {
+        return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 
-    public static String join(char[] elements, String separator) {
-        return (elements == null) ? null : join(elements, separator, 0, elements.length);
+    public static String join(final char[] elements, String separator) {
+        return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 
-    public static String join(double[] elements, String separator) {
-        return (elements == null) ? null : join(elements, separator, 0, elements.length);
+    public static String join(final double[] elements, String separator) {
+        return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 
-    public static String join(float[] elements, String separator) {
-        return (elements == null) ? null : join(elements, separator, 0, elements.length);
+    public static String join(final float[] elements, String separator) {
+        return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 
-    public static String join(int[] elements, String separator) {
-        return (elements == null) ? null : join(elements, separator, 0, elements.length);
+    public static String join(final int[] elements, String separator) {
+        return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 
-    public static String join(long[] elements, String separator) {
-        return (elements == null) ? null : join(elements, separator, 0, elements.length);
+    public static String join(final long[] elements, String separator) {
+        return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 
-    public static String join(short[] elements, String separator) {
-        return (elements == null) ? null : join(elements, separator, 0, elements.length);
+    public static String join(final short[] elements, String separator) {
+        return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 
     /**

From ffe3177863038abfaee12d6ab9d447db36010703 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Thu, 5 Aug 2021 18:46:01 +0200
Subject: [PATCH 20/24] Code review fix - brought back helper method

---
 .../org/apache/commons/lang3/StringUtils.java | 22 +++++++++++--------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index e0ce1738e69..6ac1ed242ea 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -3962,7 +3962,7 @@ public static String join(final boolean[] array, final String delimiter, final i
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
+        final StringJoiner joiner = newStringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4074,7 +4074,7 @@ public static String join(final byte[] array, final String delimiter, final int
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
+        final StringJoiner joiner = newStringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4186,7 +4186,7 @@ public static String join(final char[] array, final String delimiter, final int
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
+        final StringJoiner joiner = newStringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4298,7 +4298,7 @@ public static String join(final double[] array, final String delimiter, final in
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
+        final StringJoiner joiner = newStringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4410,7 +4410,7 @@ public static String join(final float[] array, final String delimiter, final int
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
+        final StringJoiner joiner = newStringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4522,7 +4522,7 @@ public static String join(final int[] array, final String delimiter, final int s
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
+        final StringJoiner joiner = newStringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -4843,7 +4843,7 @@ public static String join(final long[] array, final String delimiter, final int
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
+        final StringJoiner joiner = newStringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(toStringOrEmpty(array[i]));
         }
@@ -4981,7 +4981,7 @@ public static String join(final Object[] array, final String delimiter, final in
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
+        final StringJoiner joiner = newStringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(toStringOrEmpty(array[i]));
         }
@@ -5093,7 +5093,7 @@ public static String join(final short[] array, final String delimiter, final int
         if (endIndex - startIndex <= 0) {
             return EMPTY;
         }
-        final StringJoiner joiner = new StringJoiner(toStringOrEmpty(delimiter));
+        final StringJoiner joiner = newStringJoiner(delimiter);
         for (int i = startIndex; i < endIndex; i++) {
             joiner.add(String.valueOf(array[i]));
         }
@@ -5821,6 +5821,10 @@ public static String mid(final String str, int pos, final int len) {
         return str.substring(pos, pos + len);
     }
 
+    private static StringJoiner newStringJoiner(final String delimiter) {
+        return new StringJoiner(toStringOrEmpty(delimiter));
+    }
+
     /**
      * <p>
      * Similar to <a

From 170c7cbac18512f80bff519e38c978fe0a3b49e8 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Thu, 5 Aug 2021 19:07:03 +0200
Subject: [PATCH 21/24] Code review fix - Javadocs

---
 .../org/apache/commons/lang3/StringUtils.java | 105 +++++++-----------
 1 file changed, 38 insertions(+), 67 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index 6ac1ed242ea..7e136c484e6 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -3926,20 +3926,17 @@ public static String join(final boolean[] array, final char delimiter, final int
     }
 
     /**
-     * <p>
-     * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
+     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
      *
-     * <p>
-     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
-     * by empty strings.
-     * </p>
+     * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.</p>
      *
      * <pre>
      * StringUtils.join(null, *)                   = null
      * StringUtils.join([], *)                     = ""
      * StringUtils.join([null], *)                 = ""
-     * StringUtils.join([true, false, true], ';')  = "true;false;true"
+     * StringUtils.join([true, false, true], ";")  = "true;false;true"
+     * StringUtils.join([true, false, true], null) = "truefalsetrue"
      * </pre>
      *
      * @param array
@@ -4037,21 +4034,17 @@ public static String join(final byte[] array, final char delimiter, final int st
     }
 
     /**
-     * <p>
-     * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
+     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
      *
-     * <p>
-     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
-     * by empty strings.
-     * </p>
+     * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.</p>
      *
      * <pre>
      * StringUtils.join(null, *)               = null
      * StringUtils.join([], *)                 = ""
      * StringUtils.join([null], *)             = ""
-     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
-     * StringUtils.join([1, 2, 3], null) = "123"
+     * StringUtils.join([1, 2, 3], ";")        = "1;2;3"
+     * StringUtils.join([1, 2, 3], null)       = "123"
      * </pre>
      *
      * @param array
@@ -4149,21 +4142,17 @@ public static String join(final char[] array, final char delimiter, final int st
     }
 
     /**
-     * <p>
-     * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
+     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
      *
-     * <p>
-     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
-     * by empty strings.
-     * </p>
+     * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.</p>
      *
      * <pre>
      * StringUtils.join(null, *)               = null
      * StringUtils.join([], *)                 = ""
      * StringUtils.join([null], *)             = ""
-     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
-     * StringUtils.join([1, 2, 3], null) = "123"
+     * StringUtils.join(['a', 'b', 'c'], ";")  = "a;b;c"
+     * StringUtils.join(['a',b','c'], null)    = "abc"
      * </pre>
      *
      * @param array
@@ -4261,21 +4250,17 @@ public static String join(final double[] array, final char delimiter, final int
     }
 
     /**
-     * <p>
-     * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
+     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
      *
-     * <p>
-     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
-     * by empty strings.
-     * </p>
+     * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.</p>
      *
      * <pre>
      * StringUtils.join(null, *)               = null
      * StringUtils.join([], *)                 = ""
      * StringUtils.join([null], *)             = ""
-     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
-     * StringUtils.join([1, 2, 3], null) = "123"
+     * StringUtils.join([1.0, 2.0, 3.0], ";")  = "1.0;2.0;3.0"
+     * StringUtils.join([1.0, 2.0, 3.0], null) = "1.02.03.0"
      * </pre>
      *
      * @param array
@@ -4373,21 +4358,17 @@ public static String join(final float[] array, final char delimiter, final int s
     }
 
     /**
-     * <p>
-     * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
+     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
      *
-     * <p>
-     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
-     * by empty strings.
-     * </p>
+     * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.</p>
      *
      * <pre>
      * StringUtils.join(null, *)               = null
      * StringUtils.join([], *)                 = ""
      * StringUtils.join([null], *)             = ""
-     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
-     * StringUtils.join([1, 2, 3], null) = "123"
+     * StringUtils.join([1.0, 2.0, 3.0], ";")  = "1.0;2.0;3.0"
+     * StringUtils.join([1.0, 2.0, 3.0], null) = "1.02.03.0"
      * </pre>
      *
      * @param array
@@ -4485,21 +4466,17 @@ public static String join(final int[] array, final char delimiter, final int sta
     }
 
     /**
-     * <p>
-     * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
+     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
      *
-     * <p>
-     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
-     * by empty strings.
-     * </p>
+     * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.</p>
      *
      * <pre>
      * StringUtils.join(null, *)               = null
      * StringUtils.join([], *)                 = ""
      * StringUtils.join([null], *)             = ""
-     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
-     * StringUtils.join([1, 2, 3], null) = "123"
+     * StringUtils.join([1, 2, 3], ";")        = "1;2;3"
+     * StringUtils.join([1, 2, 3], null)       = "123"
      * </pre>
      *
      * @param array
@@ -4806,21 +4783,17 @@ public static String join(final long[] array, final char delimiter, final int st
     }
 
     /**
-     * <p>
-     * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
+     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
      *
-     * <p>
-     * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
-     * by empty strings.
-     * </p>
+     * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.</p>
      *
      * <pre>
      * StringUtils.join(null, *)               = null
      * StringUtils.join([], *)                 = ""
      * StringUtils.join([null], *)             = ""
-     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
-     * StringUtils.join([1, 2, 3], null) = "123"
+     * StringUtils.join([1, 2, 3], ";")        = "1;2;3"
+     * StringUtils.join([1, 2, 3], null)       = "123"
      * </pre>
      *
      * @param array
@@ -5056,9 +5029,7 @@ public static String join(final short[] array, final char delimiter, final int s
     }
 
     /**
-     * <p>
-     * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
+     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
      *
      * <p>
      * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
@@ -5069,8 +5040,8 @@ public static String join(final short[] array, final char delimiter, final int s
      * StringUtils.join(null, *)               = null
      * StringUtils.join([], *)                 = ""
      * StringUtils.join([null], *)             = ""
-     * StringUtils.join([1, 2, 3], ';')  = "1;2;3"
-     * StringUtils.join([1, 2, 3], null) = "123"
+     * StringUtils.join([1, 2, 3], ";")        = "1;2;3"
+     * StringUtils.join([1, 2, 3], null)       = "123"
      * </pre>
      *
      * @param array

From 9c29274049f6140df3cc6f14e88a8c25f1597d3f Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Thu, 5 Aug 2021 21:18:38 +0200
Subject: [PATCH 22/24] Code review fix - added missing Javadocs

---
 .../org/apache/commons/lang3/StringUtils.java | 187 +++++++++++++++++-
 1 file changed, 179 insertions(+), 8 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index 7e136c484e6..de94c4c3047 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -5098,35 +5098,206 @@ public static <T> String join(final T... elements) {
         return join(elements, null);
     }
 
-    public static String join(final byte[] elements, String separator) {
+    /**
+     * <p>Joins the elements of the provided array into a single String
+     * containing the provided list of elements.</p>
+     *
+     * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.</p>
+     *
+     * <pre>
+     * StringUtils.join(null)            = null
+     * StringUtils.join([])              = ""
+     * StringUtils.join([null])          = ""
+     * StringUtils.join([1, 2, 3], ";")  = "1;2;3"
+     * StringUtils.join([1, 2, 3], null) = "123"
+     * </pre>
+     *
+     * @param elements
+     *            the values to join together, may be null
+     * @param separator
+     *            the separator String to use
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
+    public static String join(final byte[] elements, final String separator) {
         return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 
-    public static String join(final boolean[] elements, String separator) {
+    /**
+     * <p>Joins the elements of the provided array into a single String
+     * containing the provided list of elements.</p>
+     *
+     * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.</p>
+     *
+     * <pre>
+     * StringUtils.join(null)                     = null
+     * StringUtils.join([])                       = ""
+     * StringUtils.join([null])                   = ""
+     * StringUtils.join([false,true,false], ";")  = "false;true;false"
+     * StringUtils.join([false,true,false], null) = "falsetruefalse"
+     * </pre>
+     *
+     * @param elements
+     *            the values to join together, may be null
+     * @param separator
+     *            the separator String to use
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
+    public static String join(final boolean[] elements, final String separator) {
         return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 
-    public static String join(final char[] elements, String separator) {
+    /**
+     * <p>Joins the elements of the provided array into a single String
+     * containing the provided list of elements.</p>
+     *
+     * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.</p>
+     *
+     * <pre>
+     * StringUtils.join(null)                   = null
+     * StringUtils.join([])                     = ""
+     * StringUtils.join([null])                 = ""
+     * StringUtils.join(['a', 'b', 'c'], ";")   = "a;b;c"
+     * StringUtils.join(['a', 'b', 'c'], null)  = "abc"
+     * </pre>
+     *
+     * @param elements
+     *            the values to join together, may be null
+     * @param separator
+     *            the separator String to use
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
+    public static String join(final char[] elements, final String separator) {
         return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 
-    public static String join(final double[] elements, String separator) {
+    /**
+     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     *
+     * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.</p>
+     *
+     * <pre>
+     * StringUtils.join(null)                   = null
+     * StringUtils.join([])                     = ""
+     * StringUtils.join([null])                 = ""
+     * StringUtils.join([1.0, 2.0, 3.0], ";")   = "1.0;2.0;3.0"
+     * StringUtils.join([1.0, 2.0, 3.0], null)  = "1.02.03.0"
+     * </pre>
+     *
+     * @param elements
+     *            the values to join together, may be null
+     * @param separator
+     *            the separator String to use
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
+    public static String join(final double[] elements, final String separator) {
         return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 
-    public static String join(final float[] elements, String separator) {
+    /**
+     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     *
+     * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.</p>
+     *
+     * <pre>
+     * StringUtils.join(null)                   = null
+     * StringUtils.join([])                     = ""
+     * StringUtils.join([null])                 = ""
+     * StringUtils.join([1.0, 2.0, 3.0], ";")   = "1.0;2.0;3.0"
+     * StringUtils.join([1.0, 2.0, 3.0], null)  = "1.02.03.0"
+     * </pre>
+     *
+     * @param elements
+     *            the values to join together, may be null
+     * @param separator
+     *            the separator String to use
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
+    public static String join(final float[] elements, final String separator) {
         return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 
-    public static String join(final int[] elements, String separator) {
+    /**
+     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     *
+     * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.</p>
+     *
+     * <pre>
+     * StringUtils.join(null)                   = null
+     * StringUtils.join([])                     = ""
+     * StringUtils.join([null])                 = ""
+     * StringUtils.join([1, 2, 3], ";")         = "1;2;3"
+     * StringUtils.join([1, 2, 3], null)        = "123"
+     * </pre>
+     *
+     * @param elements
+     *            the values to join together, may be null
+     * @param separator
+     *            the separator String to use
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
+    public static String join(final int[] elements, final String separator) {
         return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 
-    public static String join(final long[] elements, String separator) {
+    /**
+     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     *
+     * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.</p>
+     *
+     * <pre>
+     * StringUtils.join(null)                   = null
+     * StringUtils.join([])                     = ""
+     * StringUtils.join([null])                 = ""
+     * StringUtils.join([1, 2, 3], ";")         = "1;2;3"
+     * StringUtils.join([1, 2, 3], null)        = "123"
+     * </pre>
+     *
+     * @param elements
+     *            the values to join together, may be null
+     * @param separator
+     *            the separator String to use
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
+    public static String join(final long[] elements, final String separator) {
         return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 
-    public static String join(final short[] elements, String separator) {
+    /**
+     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     *
+     * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
+     * by empty strings.</p>
+     *
+     * <pre>
+     * StringUtils.join(null)                   = null
+     * StringUtils.join([])                     = ""
+     * StringUtils.join([null])                 = ""
+     * StringUtils.join([1, 2, 3], ";")         = "1;2;3"
+     * StringUtils.join([1, 2, 3], null)        = "123"
+     * </pre>
+     *
+     * @param elements
+     *            the values to join together, may be null
+     * @param separator
+     *            the separator String to use
+     * @return the joined String, {@code null} if null array input
+     * @since 3.13.0
+     */
+    public static String join(final short[] elements, final String separator) {
         return elements == null ? null : join(elements, separator, 0, elements.length);
     }
 

From 5b1a23e2a740bf276cc2bffd53e9457dbbd66887 Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Sun, 22 Aug 2021 09:07:16 +0200
Subject: [PATCH 23/24] Fix: Javadoc - removed paragraph tag from first line

---
 .../org/apache/commons/lang3/StringUtils.java | 58 +++++++------------
 1 file changed, 21 insertions(+), 37 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index de94c4c3047..17837dd1042 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -3926,7 +3926,7 @@ public static String join(final boolean[] array, final char delimiter, final int
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
      *
      * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
      * by empty strings.</p>
@@ -4034,7 +4034,7 @@ public static String join(final byte[] array, final char delimiter, final int st
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
      *
      * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
      * by empty strings.</p>
@@ -4107,9 +4107,7 @@ public static String join(final char[] array, final char delimiter) {
     }
 
     /**
-     * <p>
      * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
      *
      * <p>
      * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
@@ -4142,7 +4140,7 @@ public static String join(final char[] array, final char delimiter, final int st
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
      *
      * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
      * by empty strings.</p>
@@ -4183,9 +4181,7 @@ public static String join(final char[] array, final String delimiter, final int
     }
 
     /**
-     * <p>
      * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
      *
      * <p>
      * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
@@ -4215,9 +4211,7 @@ public static String join(final double[] array, final char delimiter) {
     }
 
     /**
-     * <p>
      * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
      *
      * <p>
      * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
@@ -4250,7 +4244,7 @@ public static String join(final double[] array, final char delimiter, final int
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
      *
      * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
      * by empty strings.</p>
@@ -4291,9 +4285,7 @@ public static String join(final double[] array, final String delimiter, final in
     }
 
     /**
-     * <p>
      * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
      *
      * <p>
      * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
@@ -4323,9 +4315,7 @@ public static String join(final float[] array, final char delimiter) {
     }
 
     /**
-     * <p>
      * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
      *
      * <p>
      * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
@@ -4358,7 +4348,7 @@ public static String join(final float[] array, final char delimiter, final int s
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
      *
      * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
      * by empty strings.</p>
@@ -4399,9 +4389,7 @@ public static String join(final float[] array, final String delimiter, final int
     }
 
     /**
-     * <p>
      * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
      *
      * <p>
      * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
@@ -4431,9 +4419,7 @@ public static String join(final int[] array, final char separator) {
     }
 
     /**
-     * <p>
      * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
      *
      * <p>
      * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
@@ -4466,7 +4452,7 @@ public static String join(final int[] array, final char delimiter, final int sta
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
      *
      * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
      * by empty strings.</p>
@@ -4748,9 +4734,7 @@ public static String join(final long[] array, final char separator) {
     }
 
     /**
-     * <p>
      * Joins the elements of the provided array into a single String containing the provided list of elements.
-     * </p>
      *
      * <p>
      * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
@@ -4783,7 +4767,7 @@ public static String join(final long[] array, final char delimiter, final int st
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
      *
      * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
      * by empty strings.</p>
@@ -5029,7 +5013,7 @@ public static String join(final short[] array, final char delimiter, final int s
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
      *
      * <p>
      * No delimiter is added before or after the list. Null objects or empty strings within the array are represented
@@ -5072,8 +5056,8 @@ public static String join(final short[] array, final String delimiter, final int
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String
-     * containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String
+     * containing the provided list of elements.
      *
      * <p>No separator is added to the joined String.
      * Null objects or empty strings within the array are represented by
@@ -5099,8 +5083,8 @@ public static <T> String join(final T... elements) {
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String
-     * containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String
+     * containing the provided list of elements.
      *
      * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
      * by empty strings.</p>
@@ -5125,8 +5109,8 @@ public static String join(final byte[] elements, final String separator) {
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String
-     * containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String
+     * containing the provided list of elements.
      *
      * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
      * by empty strings.</p>
@@ -5151,8 +5135,8 @@ public static String join(final boolean[] elements, final String separator) {
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String
-     * containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String
+     * containing the provided list of elements.
      *
      * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
      * by empty strings.</p>
@@ -5177,7 +5161,7 @@ public static String join(final char[] elements, final String separator) {
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
      *
      * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
      * by empty strings.</p>
@@ -5202,7 +5186,7 @@ public static String join(final double[] elements, final String separator) {
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
      *
      * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
      * by empty strings.</p>
@@ -5227,7 +5211,7 @@ public static String join(final float[] elements, final String separator) {
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
      *
      * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
      * by empty strings.</p>
@@ -5252,7 +5236,7 @@ public static String join(final int[] elements, final String separator) {
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
      *
      * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
      * by empty strings.</p>
@@ -5277,7 +5261,7 @@ public static String join(final long[] elements, final String separator) {
     }
 
     /**
-     * <p>Joins the elements of the provided array into a single String containing the provided list of elements.</p>
+     * Joins the elements of the provided array into a single String containing the provided list of elements.
      *
      * <p>No delimiter is added before or after the list. Null objects or empty strings within the array are represented
      * by empty strings.</p>

From 26f3b05a71bebafff7793f4700375f00e9a7847b Mon Sep 17 00:00:00 2001
From: Hubert Wo <2518652+HubertWo@users.noreply.github.com>
Date: Fri, 3 Sep 2021 05:01:42 +0200
Subject: [PATCH 24/24] Tests for StringUtils.join - null array, String
 separator

---
 .../java/org/apache/commons/lang3/StringUtilsTest.java   | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
index 6e29d1d4da8..fad6a944db6 100644
--- a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
@@ -1144,6 +1144,7 @@ public void testJoin_ArrayCharSeparator() {
         assertEquals("", StringUtils.join(MIXED_TYPE_LIST, '/', 2, 1));
         assertEquals("1,2", StringUtils.join(CHAR_PRIM_LIST, SEPARATOR));
         assertEquals("12", StringUtils.join(CHAR_PRIM_LIST, null));
+        assertNull(StringUtils.join((Object []) null, SEPARATOR));
     }
 
     @Test
@@ -1156,6 +1157,7 @@ public void testJoin_ArrayOfBytes() {
         assertEquals(StringUtils.EMPTY, StringUtils.join(BYTE_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
         assertEquals("1,2", StringUtils.join(BYTE_PRIM_LIST, SEPARATOR));
         assertEquals("12", StringUtils.join(BYTE_PRIM_LIST, null));
+        assertNull(StringUtils.join((byte[]) null, SEPARATOR));
     }
 
 
@@ -1171,6 +1173,7 @@ public void testJoin_ArrayOfBooleans() {
         assertEquals(StringUtils.EMPTY, StringUtils.join(ARRAY_FALSE_TRUE_FALSE, SEPARATOR_CHAR, 1, 0));
         assertEquals("false,true,false", StringUtils.join(ARRAY_FALSE_TRUE_FALSE, SEPARATOR));
         assertEquals("falsetruefalse", StringUtils.join(ARRAY_FALSE_TRUE_FALSE, null));
+        assertNull(StringUtils.join((boolean[]) null, SEPARATOR));
     }
 
     @Test
@@ -1183,6 +1186,7 @@ public void testJoin_ArrayOfChars() {
         assertEquals(StringUtils.EMPTY, StringUtils.join(CHAR_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
         assertEquals("1,2", StringUtils.join(CHAR_PRIM_LIST, SEPARATOR));
         assertEquals("12", StringUtils.join(CHAR_PRIM_LIST, null));
+        assertNull(StringUtils.join((char[]) null, SEPARATOR));
     }
 
     @Test
@@ -1195,6 +1199,7 @@ public void testJoin_ArrayOfDoubles() {
         assertEquals(StringUtils.EMPTY, StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
         assertEquals("1.0,2.0", StringUtils.join(DOUBLE_PRIM_LIST, SEPARATOR));
         assertEquals("1.02.0", StringUtils.join(DOUBLE_PRIM_LIST, null));
+        assertNull(StringUtils.join((double[]) null, SEPARATOR));
     }
 
     @Test
@@ -1207,6 +1212,7 @@ public void testJoin_ArrayOfFloats() {
         assertEquals(StringUtils.EMPTY, StringUtils.join(FLOAT_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
         assertEquals("1.0,2.0", StringUtils.join(FLOAT_PRIM_LIST, SEPARATOR));
         assertEquals("1.02.0", StringUtils.join(FLOAT_PRIM_LIST, null));
+        assertNull(StringUtils.join((float[]) null, SEPARATOR));
     }
 
     @Test
@@ -1219,6 +1225,7 @@ public void testJoin_ArrayOfInts() {
         assertEquals(StringUtils.EMPTY, StringUtils.join(INT_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
         assertEquals("1,2", StringUtils.join(INT_PRIM_LIST, SEPARATOR));
         assertEquals("12", StringUtils.join(INT_PRIM_LIST, null));
+        assertNull(StringUtils.join((int[]) null, SEPARATOR));
     }
 
     @Test
@@ -1231,6 +1238,7 @@ public void testJoin_ArrayOfLongs() {
         assertEquals(StringUtils.EMPTY, StringUtils.join(LONG_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
         assertEquals("1,2", StringUtils.join(LONG_PRIM_LIST, SEPARATOR));
         assertEquals("12", StringUtils.join(LONG_PRIM_LIST, null));
+        assertNull(StringUtils.join((long[]) null, SEPARATOR));
     }
 
     @Test
@@ -1243,6 +1251,7 @@ public void testJoin_ArrayOfShorts() {
         assertEquals(StringUtils.EMPTY, StringUtils.join(SHORT_PRIM_LIST, SEPARATOR_CHAR, 1, 0));
         assertEquals("1,2", StringUtils.join(SHORT_PRIM_LIST, SEPARATOR));
         assertEquals("12", StringUtils.join(SHORT_PRIM_LIST, null));
+        assertNull(StringUtils.join((short[]) null, SEPARATOR));
     }
 
     @Test