wait ，notfiy 配合synchronized关键字使用，wait立即释放锁，而notify并不立即释放

最新推荐文章于 2021-09-16 20:15:51 发布

god_love_hlq_xff

最新推荐文章于 2021-09-16 20:15:51 发布

阅读量958

点赞数

CC 4.0 BY-SA版权

分类专栏： java多线程

本文链接：https://blog.youkuaiyun.com/Java_Jsp_Ssh/article/details/78503460

java多线程专栏收录该内容

52 篇文章

订阅专栏

本文通过两个线程的示例，介绍了Java中synchronized关键字与wait/notify方法的基本用法，以及如何使用CountDownLatch来实现更精确的线程间同步。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

public class Notify {
	static Object ob = new Object();
	
	public static void main(String[] args) {
		Thread t1 = new Thread(new Runnable() {
			@Override
			public void run() {
				try {
					System.out.println("t1 start......");
					synchronized (ob) {
						System.out.println("t1 runing......");
						Thread.sleep(100);
						ob.wait();
						System.out.println("t1 end......");
					} 
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
		Thread t2 = new Thread(new Runnable() {
			@Override
			public void run() {
				try {
					System.out.println("t2 start......");
					synchronized (ob) {
						System.out.println("t2 runing......");
						ob.notify();
						System.out.println("t2 end......");
					} 
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
		
		t1.start();
		t2.start();
	}
}
输出结果：t1 start......
          t2 start......
          t1 runing......
          t2 runing...... 
          t2 end......          t1 end......
// notify执行完毕后，t1才获得锁

但是如果需要notify通知后，t1线程立即执行时，则可以用java.util.concurrent.CountDownLatch类

import java.util.concurrent.CountDownLatch;

public class Notify {
   static Object ob = new Object();

   public static void main(String[] args) {
       final CountDownLatch countDownLatch = new CountDownLatch(1);
       Thread t1 = new Thread(new Runnable() {
           @Override
           public void run() {
               try {
                   System.out.println("t1 start......");
                   //synchronized (ob) {
                       System.out.println("t1 runing......");
                       countDownLatch.await();
                       System.out.println("t1 end......");
                   //}
               } catch (Exception e) {
                   e.printStackTrace();
               }
           }
       });
       Thread t2 = new Thread(new Runnable() {
           @Override
           public void run() {
               try {
                   System.out.println("t2 start......");
                   //synchronized (ob) {
                       System.out.println("t2 runing......");
                       //ob.notify();
                       countDownLatch.countDown();
                       System.out.println("t2 end......");
                   //}
               } catch (Exception e) {
                   e.printStackTrace();
               }
           }
       });

       t1.start();
       t2.start();
   }
}
输出结果：
t2 start......
t1 start...... //等待。。。
t2 runing...... //通知等待线程
t1 runing......//t1获得通知，执行
t1 end......
t2 end......