如何优雅的两个线程交替打印0-100

阳光穿透心脏的1/2处 2024-03-08 08:52 76阅读 0赞

### 基本方法 ###

package com.meinvjianhao.thread;
    
    public class ThreadDemo1 {
        
        static volatile int num = 1;
        static Object lock = new Object();
    
        public static void main(String[] args) {
        
            TestThread01 testThread01 = new TestThread01();
            TestThread02 testThread02 = new TestThread02();
            testThread01.testThread01();
            testThread02.testThread02();
        }
    
        public static class TestThread01 {
        
            public void testThread01() {
        
                new Thread(() -> {
        
                    while (num < 100) {
        
                        synchronized (lock) {
        
                            while (num % 2 == 0) {
        
                                try {
        
                                    lock.wait();
                                } catch (InterruptedException e) {
        
                                    e.printStackTrace();
                                }
                            }
                            System.out.println(Thread.currentThread().getName() + "线程输出" + num++);
                            lock.notifyAll();
                        }
                    }
                }).start();
            }
        }
    
        public static class TestThread02 {
        
            public void testThread02() {
        
                new Thread(() -> {
        
                    while (num < 100) {
        
                        synchronized (lock) {
        
                            while (num % 2 != 0) {
        
                                try {
        
                                    lock.wait();
                                } catch (InterruptedException e) {
        
                                    e.printStackTrace();
                                }
                            }
                            System.out.println(Thread.currentThread().getName() + "线程输出" + num++);
                            lock.notifyAll();
                        }
                    }
                }).start();
            }
        }
    }

> 为什么使用while 而不使用if呢
> 
> 防止虚假唤醒

### 使用线程池 ###

package com.meinvjianhao.thread;
    
    import java.util.concurrent.ArrayBlockingQueue;
    import java.util.concurrent.ThreadPoolExecutor;
    import java.util.concurrent.TimeUnit;
    
    public class ThreadDemo02 {
        
        static volatile int num = 1;
        static Object lock = new Object();
        public static void main(String[] args) {
        
            ThreadPoolExecutor pool =
                    new ThreadPoolExecutor(2,8,2,
                            TimeUnit.SECONDS,new ArrayBlockingQueue<>(10));
            aa aa = new aa();
            bb bb = new bb();
    
            pool.execute(aa);
            pool.execute(bb);
        }
        static class aa implements Runnable{
        
            @Override
            public void run() {
        
                while (num < 100) {
        
                    synchronized (lock){
        
                        while (num % 2 ==0){
        
                            try {
        
                                lock.wait();
                            } catch (InterruptedException e) {
        
                                e.printStackTrace();
                            }
                        }
                        System.out.println(Thread.currentThread().getName()+"线程"+num++);
                        lock.notifyAll();
                    }
                }
            }
        }
        static class bb implements Runnable{
        
    
            @Override
            public void run() {
        
                while (num < 100) {
        
                    synchronized (lock){
        
                        while (num % 2 != 0){
        
                            try {
        
                                lock.wait();
                            } catch (InterruptedException e) {
        
                                e.printStackTrace();
                            }
                        }
                        System.out.println(Thread.currentThread().getName()+"线程"+num++);
                        lock.notifyAll();
                    }
                }
            }
        }
    
    
    }