JAVA多线程并发容器

1、ArrayList线程不安全；CopyOnWriteArrayList线程安全 package concurrent;

import java.util.ArrayList; import java.util.Iterator; import java.util.List; import java.util.concurrent.CopyOnWriteArrayList;

/**
 * Auth: zhouhongliang
 * Date：2019/8/1
 * CopyOnWriteArrayList 替代 ArrayList
 */
public class CopyOnWriteArrayListDemo {
    public static void main(String[] args) {
        List<Integer> list = new CopyOnWriteArrayList<>();
        //List<Integer> list = new CopyOnWriteArrayList<>();
        for (int i=0;i<1000;i++){
            list.add(i);
        }
        Iterator iterator = list.iterator();
        while(iterator.hasNext()){
            list.remove(iterator.next());
        }
        System.out.println(list);
    }
}

2、HashMap线程不安全；HashTable synchronize线程安全、``` ConcurrentHashMap采用”分段锁”线程安全； package concurrent;

import java.util.HashMap; import java.util.Hashtable; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.CountDownLatch; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors;

/**

• Auth: zhouhongliang
• Date：2019/8/1 */ public class ConcurrentHashMapDemo { public static void main(String[] args) throws InterruptedException { Map map = new HashMap();//线程不安全 //Map map = new Hashtable();//线程安全 //Map map = new ConcurrentHashMap();//线程安全 ExecutorService executorService = Executors.newCachedThreadPool(); CountDownLatch countDownLatch = new CountDownLatch(10000); for (int i=0;i<10000;i++){ final Integer index = i; executorService.execute(()->{ map.put(index,index); countDownLatch.countDown(); }); } countDownLatch.await(); System.out.println(map.size()); } }