class ThreadSafeSingleton {

  private static ThreadSafeSingleton threadSafeSingleton;
  /**
  * private constructor so that other classes can't
  * instantiate it through constructor
  * any instantiation while creating new singleton instance should come here
  */

  private ThreadSafeSingleton() {}

  public static synchronized ThreadSafeSingleton getInstance() {
     if(threadSafeSingleton == null) {
         threadSafeSingleton = new ThreadSafeSingleton();
     }
     return threadSafeSingleton;
  }
}