CODEWITHSUNDEEP
java
Russiancold
Russiancold

Reputation: 1311

Java abstract class constants

I have the following abstract class:

public abstract class GameObject {
protected final GameSession session;
protected final int id;
protected Point position;

public GameObject(GameSession session, Point position) {
    this.position = position;
    this.id = session.getNewId();
    this.session = session;
}

public void setPosition(Point position) {
    this.position = position;
}

public int getId() {
    return id;
}

public Point getPosition() {
    return position;
}

Each gameObject also contains constants WIDTH and HEIGHT. I want to add method getBar() for all game objects which supposed to use these constants. Here an example of game object:

public class Wall extends GameObject {
private static final Logger logger = LogManager.getLogger(Wall.class);
private static final int WIDTH = 32;
private static final int HEIGHT = 32;

public Wall(GameSession session, Point position) {
    super(session, position);
    logger.info("New Wall id={}, position={}", id, position);
}

And getbar() if it were in Wall class:

public Bar getBar() {
    return new Bar(position, position.getX() + WIDTH, position.getY() + HEIGHT);
}

How should I implement GameObject correctly? The problem is that i can't just initialize WIDTH and HEIGHT inside because they are different in subclasses.

Upvotes: 2

Views: 1170

Answers (1)

rkosegi
rkosegi

Reputation: 14658

Define abstract method getBar() in your abstract class GameObject

public abstract Bar getBar()

Then all classes which extends GameObject must implement them. So for example Wall class will have method

@Override
public Bar getBar() {
    return new Bar(position, position.getX() + WIDTH, position.getY() + HEIGHT);
}

Alternatively you can create constructor in GameObject which will also takes these constants and then you can have single method call (no need to override it):

public abstract class GameObject {
    protected final GameSession session;
    protected final int id;
    protected Point position;
    protected final width;
    protected final height;

public GameObject(GameSession session, Point position, int width, int height) {
    this.position = position;
    this.id = session.getNewId();
    this.session = session;
    this.width = width;
    this.height = height;
}

    public Bar getBar() {
        return new Bar(position, position.getX() + width, position.getY() + height);
    }
}

then in your Wall class

public Wall(GameSession session, Point position) {
    super(session, position, 32, 32); //Added WIDTH and HEIGHT
    logger.info("New Wall id={}, position={}", id, position);
}

Upvotes: 2

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