The Command pattern and the Strategy pattern are both behavioral patterns in Java that involve encapsulating behavior, but they have different intents and implementations.
The Command pattern is used to encapsulate a request as an object, allowing the request to be parameterized, queued, or logged. It involves decoupling the sender of a request from the object that executes the request. The Command pattern typically involves a command interface or class, concrete command classes that implement the command interface and encapsulate a request as an object, a receiver class that performs the actual work of the request, and a client that creates the commands and sets the receiver.
The Strategy pattern, on the other hand, is used to encapsulate interchangeable behaviors and select them at runtime. It involves decoupling an algorithm from the client that uses it, allowing different algorithms to be selected based on the context. The Strategy pattern typically involves a strategy interface or class, concrete strategy classes that implement the strategy interface and encapsulate different algorithms, and a context class that uses the strategy to perform a task.
In summary, the main difference between the Command pattern and the Strategy pattern in Java is that the Command pattern is used to encapsulate a request as an object, allowing it to be parameterized, queued, or logged, while the Strategy pattern is used to encapsulate interchangeable behaviors and select them at runtime based on the context.