CurrentHashMap多个线程同时遍历与更新----验证CurrentHashMap是线程安全的

最新推荐文章于 2025-06-25 10:49:47 发布

原创最新推荐文章于 2025-06-25 10:49:47 发布 · 2.9k 阅读

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本文介绍了一个使用Java进行并发编程的示例，通过创建一个包含消息操作的类Message和继承自Thread的类MyThread，演示了如何在多线程环境下安全地操作ConcurrentHashMap。文章详细展示了addMessage、removeMessage、updateMessage和iteratorMessage等方法的实现，以及它们在多线程环境下的运行情况。

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package com;

import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public class Message {
private ConcurrentHashMap<String,String> messageMap ;

public Message(ConcurrentHashMap messageMap) {
    messageMap.put("1","1");
    messageMap.put("2","2");
    messageMap.put("3","3");
    this.messageMap = messageMap;
}

public void addMessage(){
    messageMap.put("4","4");
    System.out.println("add message");
}

public void removeMessage(){
    messageMap.remove("1");
    System.out.println("remove message");
}

public void updateMessage(){
    messageMap.put("2","22");
    System.out.println("update message");
}

public void iteratorMessage(){
   Iterator<Map.Entry<String,String>> iterator =  messageMap.entrySet().iterator();
   while (iterator.hasNext()){
       Map.Entry<String,String> entry = iterator.next();
       System.out.println("遍历key为"+entry.getKey()+"value为"+entry.getValue());
       try {
           Thread.sleep(2000);
       } catch (InterruptedException e) {
           e.printStackTrace();
       }
   }
}

}

public class MyThread extends Thread{
private Message message;

public MyThread(Message message) {
    this.message = message;
}

@Override
public void run(){
    System.out.println(Thread.currentThread().getName()+"start");
    int i = 0;
    while (i++ < 5){
       message.addMessage();
       message.removeMessage();
       message.updateMessage();
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
    System.out.println(Thread.currentThread().getName()+"end");
}

public static void main(String[] args){
    ConcurrentHashMap<String,String> messageMap = new ConcurrentHashMap<String,String>();
    Message message = new Message(messageMap);
    Thread t1 = new MyThread(message);
    t1.start();
    message.iteratorMessage();
    //Thread t2 = new MyThread(message);
}

}
打印的结果为：
遍历key为1value为1
Thread-0start
add message
remove message
update message
add message
remove message
update message
遍历key为2value为22
add message
remove message
update message
遍历key为3value为3
add message
remove message
update message
遍历key为4value为4
add message
remove message
update message
Thread-0end