尝试在 Java 中实现 Bridge 模式时出错

Question

我想将 Shape 对象传递给 ShapeImp 对象，例如 Vector 或 Raster。尝试从 Circle 和 Square 的内部构造函数传递“this”时会出现错误。我想将具体形状传递给矢量或光栅。

Netbeans 行错误

super(平台, x,y, this, "Circle999");

“在调用超类型构造函数之前无法引用 this 在构造函数中泄漏 this”

package dp.bridge;

//-------Abstraction-------//

//----Abstraction-Specialization----------//
abstract class Shape{

    protected ShapeImpl platform;
    protected String type;

    Shape(String p, int x, int y, Circle s, String type){
        this.type = type;
        if(p.equals("vector"))
            platform = new Vector(x,y,s);
         if(p.equals("raster"))
            platform = new Raster(x,y,s);
    }

    public String getType() {
        return type;
    }

    
     abstract public void draw();
}
class Circle extends Shape{



    Circle(String platform, int x, int y){
        super(platform, x,y, this, "Circle999");
        
    }

    public void draw(){
        System.out.println("Circle: draw()");
        platform.draw();
    }
    
}

class Square extends Shape{

     Square(String platform, int x, int y){
        super(platform, x,y,this, "Square778");
     }

    public void draw(){
        System.out.println("Square: draw()");
        platform.draw();
    }

}

//----Abstract-Implementation------//
interface ShapeImpl{
    public void draw();

}

//--------Concreate implemenations--------//
class Raster implements ShapeImpl{

    int _x;
    int _y;
    Shape s;
    Raster(int x, int y, Shape s){
        _x = x;
        _y = y;
        this.s = s;
    }

    public void draw(){
        System.out.println("Drawing Raster "+s.getType()+ " at (" +_x + "," + _y +")");

    }
}

class Vector implements ShapeImpl{

    int _x;
    int _y;
    Shape s;
    Vector(int x, int y, Shape s){
        _x = x;
        _y = y;
        this.s = s;

    }

    public void draw(){
        System.out.println("Drawing Vector "+s.getType()+ " at (" +_x + "," + _y +")");

    }


}

//-----Client-------//
class Client{

    
    public static void main(String atgsp[]){
       Shape[] shapes= {new Circle("raster", 10, 40), new Square("vector", 2,2)};

        for(Shape s:shapes){
            s.draw();
        }
    }
}

Answer 1

您正在将一个对象传递给其自身？你不需要这样做（显然你也不能这样做）。超类中的 this 仍将解析为当前对象。

因此，不必将 this 作为参数传递给超级构造函数，只需在超级构造函数中使用 this ： new Vector(x, s ，这个）