State Design Pattern Tutorial

• State Design Pattern allows an object to change its behavior when its internal state changes.
• It is a behavioral type design pattern.
• It has State Interface which represents all behaviors (methods) the context will exhibit.
• The Concrete States in the state design pattern are the implementations of the State Interface that define behaviors specific to each state.
• It has Context Class that holds a reference to the current state and expose methods to clients.
• Useful to manage states in the applications and swtich between them.
• Easy to maintian since each state is a different class and state-specific behavior is encapsulated in its respective class.
• New states can be easily added by writing an extra class for the new state.
• E.g. States in a document, states in a game, or different modes in a GUI.