一个有意思的Java集合类

 

package com.shanxian.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
	
	private String userId;
	
	private String userName;
	
	
	private String age;

}

测试类：

package com.shanxian.test;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

import com.shanxian.entity.User;

public class Test001 {

	public static void main(String[] args) {
	
			User u1= new User("1","孙悟空","23");
		
			User u2= new User("2","猪八戒","24");
			User u3= new User("3","沙僧","25");
			
			
			User u4= new User();
			System.out.println("修改前===u1:"+u1);
			u4 = u1;
			
			u4.setUserName("小白龙");
			
			System.out.println("修改后===u1:"+u1);
			
			List list = new LinkedList<User>();
			
			list.add(u1);
			list.add(u2);
			list.add(u3);
			System.out.println("list1=="+list);
			
			for (int i = 0; i < list.size(); i++) {
				User u5= new User();
				 u5 = (User) list.get(i);
				
				if(u5.getUserId().equalsIgnoreCase("1")) {
					u5.setUserName("如来");
				}
			}
			
			System.out.println("list2=="+list);
	}

}

运行结果：

 

修改前===u1:User(userId=1, userName=孙悟空, age=23)
修改后===u1:User(userId=1, userName=小白龙, age=23)
list1==[User(userId=1, userName=小白龙, age=23), User(userId=2, userName=猪八戒, age=24), User(userId=3, userName=沙僧, age=25)]
list2==[User(userId=1, userName=如来, age=23), User(userId=2, userName=猪八戒, age=24), User(userId=3, userName=沙僧, age=25)]

我印象中 修改前 修改后 u1 的userName会改变。但是没想到list集合中也能改，尝试一下果然也会。

Java中引用果然是有意思