可重入锁线程等待唤醒示例

1.synchronized

package juc.one;

/**
 * 第一步 创建资源类，定义属性和操作方法
 * 第二步 判断 干活 通知
 * 第三步 创建多个线程，调用资源类的操作方法
 * 第四步 防止虚假唤醒问题
 */


//第一步 创建资源类，定义属性和操作方法
class Share {
    //初始值
    private  int number = 0;
    //+1的方法
    public synchronized void incr() throws InterruptedException {
        //第二步 判断 干活 通知
       while (number != 0){ //判断number值是否是0，如果不是0，等待
            this.wait();//防止虚假唤醒，要在循环里调用
        }
        //如果number值是0，就+1操作
        number++;
        System.out.println(Thread.currentThread().getName()+" :: "+number);
        //通知其他线程
        this.notifyAll();
    }

    //-1的方法
    public synchronized void decr() throws InterruptedException {
        //判断
        while(number != 1){
            this.wait();
        }
        //干活
        number--;
        System.out.println(Thread.currentThread().getName()+" :: "+number);
        //通知其他线程
        this.notifyAll();
    }
}
public class ThreadDemo1 {
    //第三步 创建多个线程，调用资源类的操作方法
    public static void main(String[] args) {
        Share share = new Share();
        //创建线程
        new Thread(()->{
            for(int i = 1; i<=10; i++){
                try {
                    share.incr();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"AA").start();

        new Thread(()->{
            for(int i = 1; i<=10; i++){
                try {
                    share.decr();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"BB").start();

        new Thread(()->{
            for(int i = 1; i<=10; i++){
                try {
                    share.incr();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"CC").start();

        new Thread(()->{
            for(int i = 1; i<=10; i++){
                try {
                    share.decr();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"DD").start();
    }
}

2.ReentrantLock

package juc.two;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

class Share {
    private int number = 0;

    //创建lock
    private Lock lock = new ReentrantLock();
    private Condition condition = lock.newCondition();

    //+1
    public void incr() throws InterruptedException {
        //上锁
        lock.lock();
        try {
            //判断
            while (number != 0){
                condition.await();
            }
            //干活
            number++;
            System.out.println(Thread.currentThread().getName()+" :: "+number);
            //通知
            condition.signalAll();
        }finally {
            //解锁
            lock.unlock();
        }
    }

    //-1
    public void decr() throws InterruptedException {
        lock.lock();
        try{
            //判断
            while (number != 1){
                condition.await();
            }
            number--;
            System.out.println(Thread.currentThread().getName()+" :: "+number);
            condition.signalAll();
        }finally {
            lock.unlock();
        }
    }
}

public class ThreadDemo2 {
    public static void main(String[] args) {
        Share share = new Share();
        //创建线程
        new Thread(()->{
            for(int i = 1; i<=10; i++){
                try {
                    share.incr();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"AA").start();

        new Thread(()->{
            for(int i = 1; i<=10; i++){
                try {
                    share.decr();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"BB").start();

        new Thread(()->{
            for(int i = 1; i<=10; i++){
                try {
                    share.incr();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"CC").start();

        new Thread(()->{
            for(int i = 1; i<=10; i++){
                try {
                    share.decr();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"DD").start();
    }
}