public class SingletonPattern {
   private double r;
   private static SingletonPattern sp;
   private SingletonPattern(){
       r = java.lang.Math.random();
   }
   public static SingletonPattern getInstance(){
       if(sp == null){
           sp = new SingletonPattern();
       }
       return sp;
   }
   public double getR(){
       return r;
   }
   public static void main(String[] args) {
       SingletonPattern sp1 = SingletonPattern.getInstance();
       SingletonPattern sp2 = SingletonPattern.getInstance();
       System.out.println(sp1.getR());
       System.out.println(sp2.getR());    
   }
}