Skill Builder 2 - Defining Classes and Methods

Learning Outcomes

By the end of this activity, a student should be able to:

1. Implement a simple Java class.
2. Include and use static fields.
3. Implement accessor and mutator methods
4. Design objects that interact with each other.

The Grok Coalition

Imagine you are writing a video game that has a character called a Grok. The Grok is a simple creature that can eat power pills and increase its power level by the amount of power available in the power pill. Let's begin by implementing a PowerPill class that represents all PowerPill objects. You will implemnet the Grok class in a future Skill Builder.

The PowerPill Class

A power pill is an object that is available for the Grok to ingest. Once taken, it transfers its power to the Grok. A client can create different power pills with varying levels of power and names. Provided below are template classes.

public class PowerPill
{
    
}

Required Activities

You are to implement the following in the PowerPill class.

1. Add a static integer field called DEFAULT_POWER and set it to 10. (NOTE: static variables can be initialized outside of constructors, but NOT INSTANCE variables!)
2. Add an integer field called power.
3. Add a String field called name.
4. Add a value constructor with a string parameter called name. Add the javadoc comment below before the constructor name.

	/**
     \* Initializes this power pill to a default power value
     \* and sets the name of the pill to name.
     \* @param name the name of this power pill.
     */

5. Add a value constructor where the first parameter is a string called name and the second parameter is an integer called power.

    	/**
         * Initializes this power pill to the value of power
         * and sets the name of the pill to name.
         * @param name the name of this power pill
         * @param power the power level of this power pill.
         */
    

6. Add getter methods with an appropriate javadoc comment for each method.

7. Add setter methods with an appropriate javadoc comment for each method.

8. Add a toString method that returns a string formatted as,

   PowerPill <name> = <power>
   

   where <name> is replaced by the PowerPill object's name and
   <power> is replaced with the PowerPill object's power

For example,

PowerPill p = new PowerPill("Pink", 20);
System.out.printn(p);

results in,

PowerPill Pink = 20

How To Use the Class

An example of how the class may be used is,

PowerPill bluePill = new PowerPill("Blue");
PowerPill redPill = new PowerPill("Red",40);

int bluePower = bluePill.getPower();
int redpower = redPill.getPower();

Implementing and Testing the Classes

In this Skill Builder, you are being asked to implement the class using the steps outlined in the Required Activity section. The class PowerPill contains TODO comments that match the steps provided in the Required Activities section.

You will notice that there are errors in the PowerPillTest class. This is because the methods required in the PowerPill class are not implemented. You MUST complete each of the requirements outlined in the Required Activity section until all syntax errors in PowerPillTest are resolved, then begin your testing.

Note: If your constructors are incorrectly implemented, then the getter methods will fail the test. So, make sure the constructors pass their tests!

In general, getting used to the idea of using the symbolic debugger to locate the source of a bug is an excellent overall strategy. So, use it on every method that fails the test! Place a breakpoint at the beginning of the method or in the test method of the test class and use the symbolic debugger to find the problem.

Happy Coding!