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Ace the AP Computer Science Exam for High Schoolers

Solution Review: Design a PlayStation

Explore how to design and implement Java classes through a detailed PlayStation game example. Learn to create classes, constructors, accessor and mutator methods, and understand object references to manage game and player data effectively. This lesson prepares you to handle real-world coding problems in AP Computer Science.

We'll cover the following...

The Game class

Rubric criteria

Java
public class Game    // Header of the class
{
    // Private instances
    private String name;
    private int levels;
    private int scorePerLevel;
    // Parameterized constructors
    public Game(String name, int scorePerLevel, int levels)
    {
        this.name = name;
        this.scorePerLevel = scorePerLevel;
        this.levels = levels;
    }
    
    // Return total number of levels
    public int getTotalLevels()
    {
        return levels;
    }
    // Updating the game information - overloaded methods
    public void updateGame(String name)
    {
        this.name = name;
    }
    public void updateGame(int scorePerLevel)
    {
        this.scorePerLevel = scorePerLevel;
    }
    public void updateGame(String name, int scorePerLevel)
    {
        this.name = name;
        this.scorePerLevel = scorePerLevel;
    }
    // Getting maximum score per level
    public int getScorePerLevel()
    {
        return scorePerLevel;
    }
}

Rubric-wise explanation

Point 1:

  • At line 1, we declare the header of the Game class. The class is public. We can’t declare a top level class as protected or private. It will always give an error.

  • According to the problem statement, we only need three private data members:

    1. name: Name of the game
    2. levels: Total levels in a game
    3. scorePerLevel: Score assigned upon level completion

Point 2:

  • Then, we make a constructor. Look at line 9. We declare a 33-parameter constructor that accepts three values for name, scorePerLevel, and levels.

Now we create some methods. It may not make sense right now as to why we make them, but it will later on.

Point 3:

  • Look at line 17. We create an accessor method: getTotalLevels(). It returns level, a private instance of the Game class.

Point 4:

  • Now we have three mutator methods, all with the same name: updateGame. This is allowed as long as they are overloading each other.

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