Flow Otus homework

flowcats/src/main/java/otus/homework/flowcats/CatsView.kt

@@ -3,6 +3,7 @@ package otus.homework.flowcats
 import android.content.Context
 import android.util.AttributeSet
 import android.widget.TextView
+import android.widget.Toast
 import androidx.constraintlayout.widget.ConstraintLayout
 
 class CatsView @JvmOverloads constructor(
@@ -11,12 +12,17 @@ class CatsView @JvmOverloads constructor(
     defStyleAttr: Int = 0
 ) : ConstraintLayout(context, attrs, defStyleAttr), ICatsView {
 
-    override fun populate(fact: Fact) {
-        findViewById<TextView>(R.id.fact_textView).text = fact.text
+    override fun populate(fact: Fact?) {
+        findViewById<TextView>(R.id.fact_textView).text = fact?.text ?: ""
+    }
+
+    override fun showError(error: String) {
+        Toast.makeText(context, error, Toast.LENGTH_LONG).show()
     }
 }
 
 interface ICatsView {
 
-    fun populate(fact: Fact)
+    fun populate(fact: Fact?)
+    fun showError(error: String)
 }

flowcats/src/main/java/otus/homework/flowcats/CatsViewModel.kt

@@ -1,25 +1,25 @@
 package otus.homework.flowcats
 
-import androidx.lifecycle.*
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.viewModelScope
 import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.flow.*
 import kotlinx.coroutines.launch
-import kotlinx.coroutines.withContext
 
 class CatsViewModel(
     private val catsRepository: CatsRepository
 ) : ViewModel() {
 
-    private val _catsLiveData = MutableLiveData<Fact>()
-    val catsLiveData: LiveData<Fact> = _catsLiveData
+    private val _catsStateFlow = MutableStateFlow<Result<Fact?>>(Result.Success(null))
+    val catsStateFlow: StateFlow<Result<Fact?>> = _catsStateFlow
 
     init {
         viewModelScope.launch {
-            withContext(Dispatchers.IO) {
-                catsRepository.listenForCatFacts().collect {
-                    _catsLiveData.value = it
-                }
-            }
+            catsRepository.listenForCatFacts()
+                .flowOn(Dispatchers.IO)
+                .catch { exception -> _catsStateFlow.value = Result.Error(exception.message ?: "") }
+                .collect { _catsStateFlow.value = Result.Success(it) }
         }
     }
 }

flowcats/src/main/java/otus/homework/flowcats/MainActivity.kt

@@ -3,6 +3,8 @@ package otus.homework.flowcats
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
 import androidx.activity.viewModels
+import androidx.lifecycle.lifecycleScope
+import kotlinx.coroutines.flow.collect
 
 class MainActivity : AppCompatActivity() {
 
@@ -14,8 +16,13 @@ class MainActivity : AppCompatActivity() {
         val view = layoutInflater.inflate(R.layout.activity_main, null) as CatsView
         setContentView(view)
 
-        catsViewModel.catsLiveData.observe(this){
-            view.populate(it)
+        lifecycleScope.launchWhenCreated {
+            catsViewModel.catsStateFlow.collect {
+                when (it) {
+                    is Result.Success -> view.populate(it.data)
+                    is Result.Error -> view.showError(it.error)
+                }
+            }
         }
     }
 }

flowcats/src/main/java/otus/homework/flowcats/Result.kt

@@ -0,0 +1,6 @@
+package otus.homework.flowcats
+
+sealed class Result<out T> {
+    class Success<T>(val data: T) : Result<T>()
+    class Error(val error: String) : Result<Nothing>()
+}

operators/src/main/java/otus/homework/flow/SampleInteractor.kt

@@ -2,6 +2,7 @@ package otus.homework.flow
 
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.*
+import java.lang.IllegalArgumentException
 
 @ExperimentalCoroutinesApi
 class SampleInteractor(
@@ -18,7 +19,12 @@ class SampleInteractor(
      * 6) возвращает результат
      */
     fun task1(): Flow<String> {
-        return flowOf()
+        return sampleRepository.produceNumbers()
+            .map { it * 5 }
+            .filter { it > 20 }
+            .filter { it % 2 != 0 }
+            .map { "$it won" }
+            .take(3)
     }
 
     /**
@@ -29,7 +35,24 @@ class SampleInteractor(
      * Если число не делится на 3,5,15 - эмитим само число
      */
     fun task2(): Flow<String> {
-        return flowOf()
+        return sampleRepository.produceNumbers()
+            .transform {
+                when {
+                    it % 3 == 0 -> {
+                        emit(it.toString())
+                        emit("Fizz")
+                    }
+                    it % 5 == 0 -> {
+                        emit(it.toString())
+                        emit("Buzz")
+                    }
+                    it % 15 == 0 -> {
+                        emit(it.toString())
+                        emit("FizzBuzz")
+                    }
+                    else -> emit(it.toString())
+                }
+            }
     }
 
     /**
@@ -38,7 +61,10 @@ class SampleInteractor(
      * Если айтемы в одно из флоу кончились то результирующий флоу также должен закончится
      */
     fun task3(): Flow<Pair<String, String>> {
-        return flowOf()
+        return sampleRepository.produceColors()
+            .zip(sampleRepository.produceForms()) { color, form ->
+                Pair(color, form)
+            }
     }
 
     /**
@@ -48,6 +74,13 @@ class SampleInteractor(
      * При любом исходе, будь то выброс исключения или успешная отработка функции вызовите метод dotsRepository.completed()
      */
     fun task4(): Flow<Int> {
-        return flowOf()
+        return sampleRepository.produceNumbers()
+            .catch { exception ->
+                if (exception is IllegalArgumentException) {
+                    emit(-1)
+                } else {
+                    throw exception
+                }
+            }.onCompletion { sampleRepository.completed() }
     }
 }