一个简单的并发程序

package p2;
public class TestThread {
    
    public static void main(String args[]) throws InterruptedException{        
        
        Thread1 t1 = new Thread1();
        new Thread(t1).start();
        new Thread(t1).start();
        new Thread(t1).start();
        new Thread(t1).start();
        t1.stop();    
                    
    }
}
class Thread1 extends Thread{
    private int tickets = 20;
     public void run(){
         while(true){
             synchronized(this){
                 if(tickets>0){
                     try {
                            Thread.sleep(10l);
                        } catch (InterruptedException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                     System.out.println(Thread.currentThread().getName()+"售票"+tickets--);
                 }
                 else{
                     break;
                 }                 
             }            
         }          
     }
}

模拟售票功能，总票数是20张，同时分四个窗口售票