java 克隆 clone

一、介绍

java中没有指针概念，所以存在对象的引用问题。如果对象作为参数传递或者直接使用=其实都是对对象的引用。也就是你修改第二个对象的同时第一个对象的内容也改变了。二者地址相同。所以java中需要通过继承Cloneable接口实现对象的克隆。

二、浅Clone

浅克隆又称影子克隆。一般情况下适用于java基本数据类型和string类型。对于复杂类型无法满足要求。

package test;

public class CloneTest implements Cloneable {
public String name;

public Object clone() {
Object clone = null;
try{
clone = super.clone();
} catch (CloneNotSupportedException e){
e.printStackTrace();
}
return clone;
}

public static void main(String[] args){
CloneTest test = new CloneTest();
CloneTest copyTest = new CloneTest();
test.name = "AAAA";
copyTest = (CloneTest)test.clone();
copyTest.name = "BBBB";
System.out.println(test.name);
System.out.println(copyTest.name);
}
}

三、深Clone

对于复杂成员，vector、数组之类的需要采用深层克隆。

package test;

public class CloneTest implements Cloneable {
public String[] name = new String[2];

public Object clone() {
CloneTest clone = null;  //注意申明的对象，后面调用clone.name需要类中有此类型
try{
clone = (CloneTest)super.clone();
clone.name = (String[])name.clone();
} catch (CloneNotSupportedException e){
e.printStackTrace();
}
return clone;
}

public static void main(String[] args){
CloneTest test = new CloneTest();
CloneTest copyTest = new CloneTest();
test.name[0] = "AAAA";
test.name[1] = "AA11";
copyTest = (CloneTest)test.clone();
copyTest.name[0] = "BBBB";
copyTest.name[1] = "BB11";
System.out.println(test.name[0]);
System.out.println(copyTest.name[0]);
}
}