Examples of single-mode embodiment

public  class  SingletonClass{

     private  static  volatile  SingletonClass instance= null ;

     public  static  SingletonClass getInstance(){

             synchronized (SingletonClass. class ){

                 if (instance== null ){

                     instance= new  SingletonClass();

                 }

             }

         return  instance;

     }

     private  SingletonClass(){}

}