Design Pattern | State Pattern
What Is the State Pattern?
- State means condition or state.
- The State pattern expresses states as classes and represents state changes by switching classes.
- In GoF design patterns, it is classified as a behavioral design pattern.
State Pattern Example Program
The example is a safe management program that changes button behavior depending on whether it is day or night.
Class Diagram
The example defines a Context interface for managing the safe’s state and communicating with the security center, a State interface for behavior in each state, concrete day and night states, and a UI context that delegates behavior to the current state.
Advantages
State-specific behavior is collected in state classes instead of being scattered through conditionals. Adding or changing states becomes easier, and the context can remain focused on state transitions and delegation.