Singleton Pattern with Lazy Initialization On Demand Holder

This is one of the better ways to implementing a singleton class (class which lets user create one and only one instance).

It uses Initialization on demand holder pattern.

public class Singleton {
 private static class LazyHolder {
  private static final Singleton instance = new Singleton();
 }
 
 public static Singleton getInstance() {
  return LazyHolder.instance;
 }
         
 private Singleton() {
  //initialize singleton instance
 }
}