Java-Singleton Pattern

• A Static Method is associated with Class(call class method) and can only directly invoke static methods and can only directly access static fields.
• A normal method can access both static and instance methods and can access static and instance fields.
• the modifier static should only used for main and test methods or specific situations
• Static Field means there is always one exactly storage location for that field
  • storage in static area of memory(not in object )
  • accessed by A.a
  • used for constants

 

• Singleton Pattern
  • create a single instance of a class that is public available
  • usually used as a storage(map, set, tree, LinkedList, ArrayList)
  • everything is private except storage constructor and class itself
    • if (storage == null){ storage a =new storage; return a; }