State Pattern vs Strategy Pattern

Difference between State Pattern vs Strategy pattern

 

Feature	State Pattern	Strategy Pattern
Purpose	Manages an object's state transitions	Chooses an algorithm/behavior at runtime
Problem it Solves	Vary behavior based on current state	Replace complex conditional logic with interchangeable algorithms
Key Intent	Object changes behavior when its internal state changes	Encapsulate different algorithms behind a single interface
Behavior Triggered By	Internal state of the object itself	External decision (e.g., user input, configuration)
Context Awareness	Context object usually triggers state change itself	Client code chooses which strategy to use
Participants	Context, State interface, Concrete States	Context, Strategy interface, Concrete Strategies
Common Usage	Workflow engines, UI controls with multiple modes	Sorting algorithms, Payment gateways, Compression algorithms
Dynamic Switching?	Yes, context switches between states itself	Yes, client switches the strategy explicitly
Example Analogy	Phone: Ringing → Silent → Airplane Mode (state changes)	Payment Processor: CreditCard, PayPal, Apple Pay strategies