Java的可复制的对象，类似这样的Python的例子

Question

所以，这里是我可以在Python做：

class Copiable(object): 

    def copy_from(self, other): 
     """ This method must be implemented by subclasses to define their 
      own copy-behaviour. Never forget to call the super-method. """ 

     pass 

    def copy(self): 
     """ Creates a new copy of the object the method is called with. """ 

     instance = self.__new__(self.__class__) 
     instance.copy_from(self) 
     return instance 

class Rectangle(Copiable): 

    def __init__(self, x, y, w, h): 
     super(Rectangle, self).__init__() 
     self.x = x 
     self.y = y 
     self.w = w 
     self.h = h 

    # Copiable 

    def copy_from(self, other): 
     self.x = other.x 
     self.y = other.y 
     self.w = other.w 
     self.h = other.h 
     super(Rectangle, self).copy_from(self) 

有我面对的Java版本的这两个问题：

• 我不知道如何创建类似Python的__new__方法的类的实例。
• 我想Copiable是一个接口，但是，我无法执行clone()方法。

你能想出一个解决方案吗？谢谢

Answer 1

Java使用new关键字来构造对象。创建一个Copiable接口不应该干扰clone()方法。

public interface Copiable<T> { 
    public T copy(); 
    public T copyFrom(T other); 
} 

public class Rectangle implements Copiable<Rectangle> { 

    private int x, y, w, h; 

    @Override 
    public Rectangle copy() { 
     return new Rectangle(); 
    } 

    @Override 
    public Rectangle copyFrom(Rectangle other) { 
     return new Rectangle(other); 
    } 

    public int getX() { 
     return x; 
    } 

    public int getY() { 
     return y; 
    } 

    public int getW() { 
     return w; 
    } 

    public int getH() { 
     return h; 
    } 

    public Rectangle() {} 
    public Rectangle(Rectangle other) { 
     this.x = other.getX(); 
     this.y = other.getY(); 
     this.w = other.getW(); 
     this.h = other.getH(); 
    } 
}