java多线程

生产者与消费者问题

package xianPack;

//生产者    消费者
public class Test10 {

    public static void main(String[] args) {
        
        final Apple apple = new Apple();
        
        //吃苹果的人      (上下两种方法一样)
        new Thread(new Runnable() {
            public void run() {
                try {
                    apple.eat();
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        },"线程1").start();
        
        Thread thread1 = new Thread(new Runnable() {
            public void run() {
                try {
                    apple.eat();
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        },"线程2");
        thread1.start();
        
        //种苹果的
        new Thread(new Runnable() {
            public void run() {
                try {
                    apple.plant();
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        },"线程3").start();
        
        new Thread(new Runnable() {
            public void run() {
                try {
                    apple.plant();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"线程4").start();
        
    }
}

class Apple {
    
    int num = 0;   //苹果的数量
    
    //吃苹果
    void eat() throws InterruptedException {
        while (true) {
            synchronized (this) {
                if (num > 0) {
                    num--;
                    Thread thread = Thread.currentThread();
                    System.out.println(thread.getName() + "吃苹果,剩下" + num);
                    //并且通知种苹果的种
                    notifyAll(); 
                }else {   //没有苹果了
                    //进入等待状态
                    wait();
                    //并且通知种苹果的种
                    //notify();    //通知一个
                }
            }
            
        }
    }
    
    //种苹果
    void plant() throws InterruptedException {
        while (true) {
            //锁放在里边  一边吃一边种
            synchronized (this) {
                //如果生产大于20个,停止生产
                if (num < 20) { 
                    this.num++;
                    Thread thread = Thread.currentThread();
                    System.err.println(thread.getName() + "种苹果,剩下" + num);
                    
                    //通知吃苹果的吃
                    notifyAll();    //通知所有的
                }else {     //苹果太多  不能生产了
                    //等待
                    wait();
                }
            }
            
        }
    }
    
    
}