java---深clone例子

 

 

public class ObjectForClone  implements Cloneable...{
        
    private int i = 0;
    
    private ReferencedObject rf = null;
   
    public void setNum(int i) ...{
        this.i = i;
    }
   
    public void setReferencedObject(ReferencedObject rf)...{
        this.rf = rf;
    }
       
    public int getNumber()...{
        return this.i;
    }
   
    public ReferencedObject getReferencedObject()...{
        return this.rf;
    }
   
    
    public Object clone() throws CloneNotSupportedException ...{
        
        ObjectForClone cloneObject = (ObjectForClone)super.clone();
        
         if(rf!=null)...{
             ReferencedObject rfClone = (ReferencedObject)rf.clone();
             cloneObject.setReferencedObject(rfClone);
         }
         return cloneObject;
     }
}

 class ReferencedObject implements Cloneable...{
    private int i = 0;
    public ReferencedObject(int i) ...{
        this.i = i;
    }
    public void doubleValue()...{
        this.i = 2*this.i;
    }
   
    public int getNumber()...{
        return this.i;
    }
    
    public Object clone() throws CloneNotSupportedException ...{
        return (ReferencedObject)super.clone();
    }
}

上面的类是要clone的类。

 

public class CloneTest  ...{
    public static void main(String[] args) ...{
        ObjectForClone ofsc = new ObjectForClone();
        ofsc.setNum(888);
        ofsc.setReferencedObject(new ReferencedObject(1));

        
        ObjectForClone deepCloneObject = null;
        try ...{
            deepCloneObject = (ObjectForClone) ofsc.clone();
        } catch (CloneNotSupportedException ex) ...{
            System.out.println("Sorry,Clone Not Supported!");
        }

        
        if(deepCloneObject!=null)...{
            System.out.println("before clone");
            System.out.println("ObjectForShallowClone get number : " + ofsc.getNumber());
            System.out.println("ObjectForShallowClone ReferencedObject get number : "+ofsc.getReferencedObject().getNumber()+" ");
           
            deepCloneObject.setNum(999);
            deepCloneObject.getReferencedObject().doubleValue();

            System.out.println("after clone");
            System.out.println("ObjectForShallowClone get number : " + ofsc.getNumber());
            System.out.println("ObjectForShallowClone ReferencedObject get number : " + ofsc.getReferencedObject().getNumber());

            System.out.println("CloneObject get number : " + deepCloneObject.getNumber());
            System.out.println("CloneObject ReferencedObject get number : " + deepCloneObject.getReferencedObject().getNumber());
        }
    }
    
}

测试类的执行结果为：

before clone
ObjectForShallowClone get number : 888
ObjectForShallowClone ReferencedObject get number : 1

after clone
ObjectForShallowClone get number : 888
ObjectForShallowClone ReferencedObject get number : 1
CloneObject get number : 999
CloneObject ReferencedObject get number : 2

从结果可以看出，程序成功完成了深clone。关键点是：

1：对于类ObjectForClone，里面有两个成员分别是

    整数的 i

   ReferencedObject类型的 rf

这两个成员属于两种不同的类型，int型的成员属于基本类型成员，另一个属于引用类型成员。注意，要成功实现ObjectForClone的深clone,还必须要先实现该类里面的引用类型成员（）的clone方法。

2：准备clone的类，除了实现Cloneable接口，还要重写clone()方法，而且要声明该方法为public。