/*等待的目的是让cpu给其他线程。*/class Resource{	private String name;	private int count = 0;	private boolean flag = false;	Resource(String name)	{		this.name = name;	}	public synchronized void product()	{		while(flag)						//此处如果是if的效果		{			try			{				wait();			}			catch (InterruptedException ex)			{							}		}		this.name = "---"+this.count;		System.out.println(Thread.currentThread().getName() + "生产者---" + this.name);		flag  = true;		this.count++;		this.notify();	}		public synchronized void consume()	{		while(!flag)					//此处如果是if的效果,如果某个线程被wait，接着又一个，然后两个都醒了，就会造成对一个产品两次消费		{			try			{				wait();			}			catch (InterruptedException ex)			{			}		}		System.out.println(Thread.currentThread().getName() + "消费者---------" + this.name);		flag = false;		this.notify();	}}class Product implements Runnable{	private Resource sr;	Product(Resource sr)	{		this.sr = sr;	}	public void run()	{		while(true)		{			if(sr != null)			{				sr.product();			}		}	}}class Consume implements Runnable{	private Resource sr;	Consume(Resource sr)	{		this.sr = sr;	}	public void run()	{		while(true)		{			if(sr != null)			{				sr.consume();			}		}	}}class DemoRunnable{	public static void main(String[] args) 	{		Resource sr = new Resource("产品");		Product p = new Product(sr);		Consume c =new Consume(sr);		Thread t1 = new Thread(p);		Thread t2 = new Thread(p);		Thread c1 = new Thread(c);		Thread c2 = new Thread(c);		Thread c3 = new Thread(c);		t1.start();		t2.start();		c1.start();		c2.start();		c3.start();	}}