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Java OOP: how to create objects correctly

I am creating a simple bowling game using OOP, and I want to have a class for each bowl, a Frame class of two bowls, and a game class of ten frames.

At the moment I have something like this

Bowl.java

public class Bowl {

int bowlScore = 0;

public Bowl(int pinsKnocked){
    bowlScore = pinsKnocked;
}
}

Frame.java

public class Frame{

int firstScore;
int secondScore;
public Bowl firstBowl;
public Bowl secondBowl;

public Frame (){
    firstBowl = new Bowl(0);
    secondBowl = new Bowl(0);
}

public Frame (int firstScore, int secondScore){
    firstBowl = new Bowl(firstScore);
    secondBowl = new Bowl(secondScore);
}

Game.java

public class Game {

int totalScore;
public Frame firstFrame;
public Frame secondFrame;
...
    public Frame tenthFrame;

public Game(){
    firstFrame = new Frame();   
}

public Game(Frame f){
    firstFrame = f;
}

Is this the right way to use OOP features, or how can I improve this?

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3 answers

There is no 100% correct way to develop a bowling game; There are many solutions that will work, and even more that will not work.

What you need is a solution that will work well for your goals and your goals.

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public class Frame{
    private Bowl firstBowl;
    private Bowl secondBowl;

    public Frame (int firstScore, int secondScore){
        firstBowl = new Bowl(firstScore);
        secondBowl = new Bowl(secondScore);
    }
    public int getFrameScore(){
       return (firstBowl.getScore()+secondBowl.getScore());
    }
}

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public class Game {
    private java.uti.List<Frame> frames;
    public Game(List<Frame> frames){
      this.frames = frames;
    }
    public getGameScore(){
      // loop goes here to sum up scores from all frames
      //sum = sum+frames.get(i);
    }
}

}

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public class Bowl {

    private int bowlScore;

    // Use a no-argument constructor
    public Bowl() {
        this.bowlScore = 0;
    }

    public void setBowlScore( int score ) {
        this.bowlScore = score;
    }

    public int getBowlScore() {
        return this.bowlScore;
    }
}

Frame

public class Frame {

    private int frameScore;
    private Bowl bowlArray[];

    public Frame() {
        this.frameScore = 0;
        this.bowlArray = new Bowl[2];
    }

    public void setScoreForFirstBowl( int score ) {
        this.bowlArray[0] = score;
        this.frameScore += score;
    }

    public void setScoreForSecondBowl( int score ) {
        this.bowlArray[1] = score;
        this.frameScore += score;
    }

    public void setFrameScore( int score ) {
        this.frameScore = score;
    }

    public int getFrameScore() {
        return this.frameScore;
    }

    // this should not be used, left in for completeness
    public Bowl[] getBowlArray() {
        return this.bowlArray;
    }
}

Game

public class Game {

     private int gameScore;
     private ArrayList<Frame> gameFrames;

     public Game() {
         this.gameScore = 0;
         this.gameFrames = new ArrayList<Frame>();
     }

     /* There are many ways of implementing the game logic. Here is an example.
        You will have to complete the rest :) */

     // @frame frame object with bowl data that is appended to list
     public void frameCompleted(Frame frame) {
         this.gameScore += frame.getFrameScore; // I assume this is what you want to do. Change if not
         this.gameFrames.add(frame);
     }

     /* The method written above can also be implemented by passing integer values
        for the score, bowl number and frame number. However, this would not be very
        OOP friendly. Essentially, this is 'Encapsulation' of the Frame data into the 
        Frame object. */

     // Add getters and setters for gameScore and gameFrames
}

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Read more about Encapsulation here and here .

You will notice that I did not take into account "strikes" in classes Bowlor Frame. This is due to the fact that this is a special case that needs to be serviced, and therefore I left it for you. I understand that if you strike the first bowl, you will not get the second bowl.

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