Java中的深复制和浅复制-白红宇

Java中的深复制和浅复制

阅读量：5320 次

发布时间：2019-06-14

本文共 4317 字，大约阅读时间需要 14 分钟。

1. 浅复制：只复制了对象的引用，实际对应的还是一个对象实例，例如下例中的Address

1 /* 2  * 浅复制 3  */ 4  5 class Address2  {   6     private String add;   7    8     public String getAdd() {   9         return add;  10     }  11   12     public void setAdd(String add) {  13         this.add = add;  14     }  15       16 }  17   18 class Student2 implements Cloneable{  19     private int number;  20   21     private Address2 addr;  22       23     public Address2 getAddr() {  24         return addr;  25     }  26   27     public void setAddr(Address2 addr) {  28         this.addr = addr;  29     }  30   31     public int getNumber() {  32         return number;  33     }  34   35     public void setNumber(int number) {  36         this.number = number;  37     }  38       39     @Override  40     public Object clone() {  41         Student2 stu = null;  42         try{  43             stu = (Student2)super.clone();  44         }catch(CloneNotSupportedException e) {  45             e.printStackTrace();  46         }  47         return stu;  48     }  49 }  50 public class CopyTest2 {  51       52     public static void main(String args[]) {  53           54         Address2 addr = new Address2();  55         addr.setAdd("杭州市");  56         Student2 stu1 = new Student2();  57         stu1.setNumber(123);  58         stu1.setAddr(addr);  59           60         Student2 stu2 = (Student2)stu1.clone();  61           62         System.out.println("学生1:" + stu1.getNumber() + ",地址:" + stu1.getAddr().getAdd());  63         System.out.println("学生2:" + stu2.getNumber() + ",地址:" + stu2.getAddr().getAdd());  64         addr.setAdd("合肥市");65         stu1.setAddr(addr);66         System.out.println("学生1:" + stu1.getNumber() + ",地址:" + stu1.getAddr().getAdd());  67         System.out.println("学生2:" + stu2.getNumber() + ",地址:" + stu2.getAddr().getAdd());68     }  69 }

2. 深复制：复制另一个实例对象，两者没有任何交叉的关系

1 /* 2  * 深复制 3  */ 4 class Address implements Cloneable {   5     private String add;   6    7     public String getAdd() {   8         return add;   9     }  10   11     public void setAdd(String add) {  12         this.add = add;  13     }  14       15     @Override  16     public Object clone() {  17         Address addr = null;  18         try{  19             addr = (Address)super.clone();  20         }catch(CloneNotSupportedException e) {  21             e.printStackTrace();  22         }  23         return addr;  24     }  25 }  26   27 class Student implements Cloneable{  28     private int number;  29   30     private Address addr;  31       32     public Address getAddr() {  33         return addr;  34     }  35   36     public void setAddr(Address addr) {  37         this.addr = addr;  38     }  39   40     public int getNumber() {  41         return number;  42     }  43   44     public void setNumber(int number) {  45         this.number = number;  46     }  47       48     @Override  49     public Object clone() {  50         Student stu = null;  51         try{  52             stu = (Student)super.clone();   //浅复制  53         }catch(CloneNotSupportedException e) {  54             e.printStackTrace();  55         }  56         stu.addr = (Address)addr.clone();   //深度复制  57         return stu;  58     }  59 }  60 public class CopyTest {  61       62     public static void main(String args[]) {  63           64         Address addr = new Address();  65         addr.setAdd("杭州市");  66         Student stu1 = new Student();  67         stu1.setNumber(123);  68         stu1.setAddr(addr);  69           70         Student stu2 = (Student)stu1.clone();  71           72         System.out.println("学生1:" + stu1.getNumber() + ",地址:" + stu1.getAddr().getAdd());  73         System.out.println("学生2:" + stu2.getNumber() + ",地址:" + stu2.getAddr().getAdd());  74           75         addr.setAdd("西湖区");  76           77         System.out.println("学生1:" + stu1.getNumber() + ",地址:" + stu1.getAddr().getAdd());  78         System.out.println("学生2:" + stu2.getNumber() + ",地址:" + stu2.getAddr().getAdd());  79     }  80 }

3. 观察两者的区别不难发现，只一点浅复制的Address类没有继承Cloneable接口，进而实现clone()方法。默认的是java.lang.Object的clone()方法。

4. 对象的序列化也能实现深复制。但需要对象中的每一种成分都是可序列化的才行。

5. Java中参数传递：值传递和引用传递的简单总结