java 拷贝 list

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.io.OutputStream;

import java.io.Serializable;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

class Person implements Cloneable,Serializable{

private String name;

public Person(String name) {

this.name = name;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

@Override

public String toString() {

return this.name;

}

@Override

protected Person clone() throws CloneNotSupportedException {

return (Person)super.clone();

}

}

public class JavaListCopy {

public static void main(String args[]) throws IOException, CloneNotSupportedException, ClassNotFoundException {

List list1 = new ArrayList();

list1.add(new Person("aaa"));

list1.add(new Person("bbb"));

// 第一种方法：通过构造函数来实现，它里面调用了Arrays.copyOf(),copyOf又调用了System.arraycopy List list2 = new ArrayList(list1);

list2.get(0).setName("ccc");

System.out.println("list1 ==>"+list1);

System.out.println("list2 ==>"+list2);

// 第二种方法：addAll方法，它调用了System.arraycopy // System.arraycopy：源数据-->目的数据 // Arrays.copyOf():源数据及长度，数据类型，它里面调用了System.arraycopy List list3 = new ArrayList();

list3.addAll(list1);

list3.get(0).setName("ddd");

System.out.println("list1 ==>"+list1);

System.out.println("list3 ==>"+list3);

// 第三种方法：实现clone来实现 List list4 = new ArrayList();

for(int i = 0; i< list1.size();i++){

list4.add(list1.get(i).clone());

}

list4.get(0).setName("eee");

System.out.println("list1 ==>"+list1);

System.out.println("list4 ==>"+list4);

// 第四种方法：通过序列化来实现 List list5 = null;

OutputStream bo = new ByteArrayOutputStream();

ObjectOutputStream oo = new ObjectOutputStream(bo);

oo.writeObject(list1);

InputStream bi = new ByteArrayInputStream(((ByteArrayOutputStream) bo).toByteArray());

ObjectInputStream oi = new ObjectInputStream(bi);

list5 = (List) oi.readObject();

list5.get(0).setName("ggg");

System.out.println("list1 ==>"+list1);

System.out.println("list5 ==>"+list5);

// 第五种方法： Collection.copy，它的实现过程是通过遍历然后set进入 List list6 = new ArrayList(Arrays.asList(new Person[list1.size()]));

Collections.copy(list6, list1);

list6.get(0).setName("hhh");

System.out.println("list1 ==>"+list1);

System.out.println("list6 ==>"+list6);

}

}