Prototype pattern - Creational

• Cloning an object by reducing the cost of creation
• Create new objects by copying the prototype
• Creates duplicate objects efficiently
• It implements a prototype interface which tells to create a clone of the current object
• Used

 
  

Where to use ?

• When direct creation of object is costly
• To use one instance to finish job just by changing its state or parameters.

Implementation example

• Abstract class Color implementing Clonable interface and overriding clone method.
• Multiple concrete classes Red, Green, Blue extending Color class.

• A cache class maintaining a Hashtable of Color type objects and 2 methods :
• Initialize cache : Make all type of objects and keep them in Hashtable
• Get object : Get object from Hashtable by calling clone method

• Client calls the cache class to initialize the cache (one time only on startup)
  Then, client calls cache class to get the object by passing a key of Hashtable