Interview Question for Software Engineer at Netflix:

Singleton design patterns deals with where you need a single instance of the class which has to be shared among multiple resources.

Singleton design pattern is used in Logger class,Shared Resource environment.

Example of singleton:

public class singleton{

  private static singleton instance=new singleton();
  private singleton(){
                             }
 public ststic getinstance()
    {
      return instance;
   }
}

another synchrinized way :

public class singleton{

   private static singleton instance;
   private singleton(){
                         }
   public static getinstance(){

     if (instance==null)
         {
             synchronized(singleton.class)
                   {
                        if(instance==null)
                            {
                                  instance=new singleton();
                            }

                 }
          }
  return instance;
   }
}