Java 抽象类常量

Question

>我有以下抽象类：

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;
}

每个gameObject还包含常量WIDTH和HEIGHT。我想为所有应该使用这些常量的游戏对象添加方法 getBar()。下面是一个游戏对象示例：

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);
}

getbar()如果它在课堂上Wall：

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

我应该如何正确实施GameObject？问题是我不能只初始化WIDTH并在里面HEIGHT，因为它们在子类中是不同的。

Answer 1

在抽象类中定义抽象方法 getBar（） GameObject

public abstract Bar getBar()

然后，所有扩展GameObject类都必须实现它们。所以例如Wall类将有方法

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

或者，您可以在GameObject中创建构造函数，该构造函数也将接受这些常量，然后您可以进行单个方法调用（无需覆盖它）：

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);
    }
}

然后在你的Wall课上

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