public static void main(String[] args) {
        Singleton s1 = Singleton.getInstance();
        Singleton s2 = Singleton.getInstance();
        System.out.println(s1 == s2);
    }

}

class Singleton {

    private static Singleton instance;

    private Singleton() {

    }
   
   //创建单例对象
//    public static Singleton  getInstance(){
//          if(instance==null){
//              instance=new Singleton();
//          }
//          return instance;
//     }
      public static Singleton getInstance(){
          return instance;
      }
    //write your code here......
    

}