线程同步1

package com.hhr.cn.tread;

public class ThreadDemo3 {

	public static void main(String[] args) {
		SellCard windows1=new SellCard();
		SellCard windows2=new SellCard();
		SellCard windows3=new SellCard();
		SellCard windows4=new SellCard();
		windows1.setName("windows1");
		windows2.setName("windows2");
		windows3.setName("windows3");
		windows4.setName("windows4");
		windows1.start();
		windows2.start();
		windows3.start();
		windows4.start();
	}

}

package com.hhr.cn.tread;
//模拟火车张卖票，，，四个窗口同时卖
public class SellCard extends Thread{
	private static int cards=20;
	@Override
	public void run() {
		while(true){
			try {
				Thread.sleep(1000);
				synchronized (SellCard.class) {//确保不同线程共享的数据（对象）是一样的
					if(cards>0){
						cards--;
						System.out.println(this.getName()+"卖票，还剩下"+cards+"张票！！");
					}else{
						System.out.println("票已经卖完");
						return;
					}
				}
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			
		}
	}
}