[20160804]synchronized

class Timer{
   private static int num;

   void add(String name){
     //synchronized (this){
       num++;
       try{  Thread.sleep(1);  }
       catch(InterruptedException e){};
       System.out.println(name+"  you are the  "+num+"  user to use timer!");
     //}
   }
}


public class TestSync implements Runnable{
    Timer timer = new Timer();

    public static void main(String[] args) {
       TestSync t = new TestSync();

       Thread t1 = new Thread(t,"t1");
       Thread t2 = new Thread(t,"t2");


       t1.start();
       t2.start();
    }

    public void run(){
       timer.add(Thread.currentThread().getName());
    }
}