How to create Profile Data singleton class?

Question

I want create singleton class But I don't know how?

Example:

class Singleton {
      Singleton singleton = null;
      public static Singleton getInstance()
      {
        if (singleton == null)
           singleton = new Singleton();
        return singleton;
      }
   }

Answer 1

Simply add static before in the singleton class.

class Singleton {
      static Singleton singleton = null;
      public static Singleton getInstance()
      {
        if (singleton == null)
           singleton = new Singleton();
        return singleton;
      }
   }