java - 向客户端代码公开构建器类

Question

我正在将我的游戏移至其自己的包中，以使其在未来的游戏中发挥作用。 我按照其中一位用户的建议实现了 Builders 类:Interfaces, static classes problem

public final class Builders {
    public static Builder<? extends Sprite> newGameObjectBuilder(Point location, int drawable) {
        return new GameObjectImpl.GameObjectBuilder(location, drawable);
    }
}

现在的问题是客户端代码无法使用构建器方法(下面的示例)。我得到以下信息:

"The method onReceiveKey(new Sprite.ReceiveKeys(){}) is undefined for the type Builder<capture#4-of ? extends Sprite>"

基本上我无法使用公共(public)静态调用 GameObjectBuilder 中的任何方法。

onReceiveKey 不起作用。仅 Builder 接口(interface)的 build() 方法可用。

public static Sprite newSoldier(int x, int y) {
    return  Builders.newGameObjectBuilder(new Point(x,y), R.drawable.soldier)
    .onReceiveKey(new Sprite.ReceiveKeys() {

        @Override
        public void onKeyUp(int keyCode, Sprite self, Room room ) {


        }

        @Override
        public void onKeyDown(int keyCode, Sprite self, Room room ) {
            if(keyCode == KeyEvent.KEYCODE_DPAD_DOWN) {
                self.moveY(room, 1, Direction.S); 
            }
            else if(keyCode == KeyEvent.KEYCODE_DPAD_UP){
                self.moveY(room, -1, Direction.N); 
            }
            else if(keyCode == KeyEvent.KEYCODE_DPAD_LEFT){
                self.moveX(room, -1,Direction.W); 
            }
            else if(keyCode == KeyEvent.KEYCODE_DPAD_RIGHT){
                self.moveX(room, 1, Direction.E);
            }
        }
    })
    .build();
}

Answer 1

问题是你的构建器是这样的

public interface Builder<T> {
    public T build();
}

就这么做

public interface SpriteBuilder<T extends Sprite> extends Builder<T> {
    Builder<T> onReceiveKey(Sprite.ReceiveKeys receiver);
}

并将构建器更改为

public final class Builders {
    public static SpriteBuilder newGameObjectBuilder(Point location, int drawable) {
        return new GameObjectImpl.GameObjectBuilder(location, drawable);
    }
}

和你的GameObjectBuilder到

class GameObjectImpl extends AbstractSprite {
    public static class GameObjectBuilder implements SpriteBuilder {
    ...
    }
}