synchronized 同步代码块，售票问题

package cn.ljs.FristSync;


public class SalerDemo extends Thread {
	
	static int tickets = 1000;
	String name;
	static Object lock = new Object();
	public SalerDemo(String name) {
		this.name = name;
	}
	public void run(){
		
		while(true){
			
			synchronized (lock) {
				if (tickets < 1) {
					return ;
				}
				System.out.println(name + ": " + tickets);
				tickets--;
			}
		}
	}
	
	public static void main(String[] args) {
		Thread t1 = new SalerDemo("saler1");
		Thread t2 = new SalerDemo("saler2");
		Thread t3 = new SalerDemo("saler3");
		t1.start();
		t2.start();
		t3.start();
		
	}
	
	
}

　

建立票池 

package cn.ljs.FristSync;

public class SalerDemo01 extends Thread{
    
    private String name;
    private TicketsPool pool;
    
    public SalerDemo01(String name, TicketsPool pool){
        this.name = name;
        this.pool = pool;
    }
    
    public void run(){
        while (true){
            int num = pool.getTickets();
            if (num != 0) {
                System.out.println(name+"卖了"+num);
            }else {
                return;
            }
        }
        
    }
    
    public static void main(String[] args) {
        
        TicketsPool pool = new TicketsPool();
        SalerDemo01 saler1 = new SalerDemo01("01", pool);
        SalerDemo01 saler2 = new SalerDemo01("02", pool);
        SalerDemo01 saler3 = new SalerDemo01("03", pool);
        
        saler1.start();
        saler2.start();
        saler3.start();
        
        
    }
    
}


class TicketsPool{
    
    private int num = 100;
    public int getTickets(){
        
        synchronized (this) {
            int tmp = num;
            num--;
            return tmp > 0 ? tmp:0;
        }
    }
    
}