java 克隆对象（转）

来源：http://www.cnblogs.com/Qian123/p/5710533.html

一般步骤是（浅克隆）：

1. 被复制的类需要实现Clonenable接口（不实现的话在调用clone方法会抛出CloneNotSupportedException异常)， 该接口为标记接口(不含任何方法)

2. 覆盖clone()方法，访问修饰符设为public。方法中调用super.clone()方法得到需要的复制对象。（native为本地方法)

下面对上面那个方法进行改造：

class Student implements Cloneable{  
    private int number;  
  
    public int getNumber() {  
        return number;  
    }  
  
    public void setNumber(int number) {  
        this.number = number;  
    }  
      
    @Override  
    public Object clone() {  
        Student stu = null;  
        try{  
            stu = (Student)super.clone();  
        }catch(CloneNotSupportedException e) {  
            e.printStackTrace();  
        }  
        return stu;  
    }  
}  
public class Test {  
    public static void main(String args[]) {  
        Student stu1 = new Student();  
        stu1.setNumber(12345);  
        Student stu2 = (Student)stu1.clone();  
          
        System.out.println("学生1:" + stu1.getNumber());  
        System.out.println("学生2:" + stu2.getNumber());  
          
        stu2.setNumber(54321);  
      
        System.out.println("学生1:" + stu1.getNumber());  
        System.out.println("学生2:" + stu2.getNumber());  
    }  
}  

结果是：

　　

结果：

学生1:12345  

学生2:12345  

学生1:12345  

学生2:54321

 

深度复制：

我们在学生类里再加一个Address类。

　　　

 package abc;  
 2   
 3 class Address implements Cloneable {  
 4     private String add;  
 5   
 6     public String getAdd() {  
 7         return add;  
 8     }  
 9   
10     public void setAdd(String add) {  
11         this.add = add;  
12     }  
13       
14     @Override  
15     public Object clone() {  
16         Address addr = null;  
17         try{  
18             addr = (Address)super.clone();  
19         }catch(CloneNotSupportedException e) {  
20             e.printStackTrace();  
21         }  
22         return addr;  
23     }  
24 }  
25   
26 class Student implements Cloneable{  
27     private int number;  
28   
29     private Address addr;  
30       
31     public Address getAddr() {  
32         return addr;  
33     }  
34   
35     public void setAddr(Address addr) {  
36         this.addr = addr;  
37     }  
38   
39     public int getNumber() {  
40         return number;  
41     }  
42   
43     public void setNumber(int number) {  
44         this.number = number;  
45     }  
46       
47     @Override  
48     public Object clone() {  
49         Student stu = null;  
50         try{  
51             stu = (Student)super.clone();   //浅复制  
52         }catch(CloneNotSupportedException e) {  
53             e.printStackTrace();  
54         }  
55         stu.addr = (Address)addr.clone();   //深度复制  
56         return stu;  
57     }  
58 }  
59 public class Test {  
60       
61     public static void main(String args[]) {  
62           
63         Address addr = new Address();  
64         addr.setAdd("杭州市");  
65         Student stu1 = new Student();  
66         stu1.setNumber(123);  
67         stu1.setAddr(addr);  
68           
69         Student stu2 = (Student)stu1.clone();  
70           
71         System.out.println("学生1:" + stu1.getNumber() + ",地址:" + stu1.getAddr().getAdd());  
72         System.out.println("学生2:" + stu2.getNumber() + ",地址:" + stu2.getAddr().getAdd());  
73           
74         addr.setAdd("西湖区");  
75           
76         System.out.println("学生1:" + stu1.getNumber() + ",地址:" + stu1.getAddr().getAdd());  
77         System.out.println("学生2:" + stu2.getNumber() + ",地址:" + stu2.getAddr().getAdd());  
78     }  
79 }  

输出结果：

　　学生1:123,地址:杭州市

　　学生2:123,地址:杭州市

　　学生1:123,地址:西湖区

　　学生2:123,地址:杭州市