关于list一个很有意思的小题

package com.sdufe.domain;

import java.util.ArrayList;

import java.util.List;

class User {

 private int num;

 public User(int num) {

  this.num = num;

 }

 public int getNum() {

  return num;

 }

 public void setNum(int num) {

  this.num = num;

 }

}

public class test {

 /**

  * @param args

  */

 public static void main(String[] args) {

  // TODO Auto-generated method stub

  List<User> userList = new ArrayList<User>();

  userList.add(new User(0));

  User user1 = new User(1);

  User user2=new User(2);

  userList.add(user1);

  userList.add(0, user2);

  System.out.println(userList);

  System.out.println(userList.size());

  for (User user : userList) {

   System.out.println("usernum==="+user.getNum());

  }

  

 }

}

问题：里面有几个User Instance  运行结果是什么

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不去跑你知道答案吗？

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