public class Single{
  private static final Single INSTANCE = new Single();
  private Single(){}
  public static Single getInstance(){
    return INSTANCE;
  } 
  public void methodA(){
    System.out.println("Call method A");
  } 
  
  public static void main(String args[]){
    Single sg1 = Single.getInstance();
    Single sg2 = Single.getInstance();
    sg1.methodA();
    sg2.methodA();	
    System.out.println(sg1==sg2);
  }
}