Learning Java Functional Programming

Implementing the command pattern

The command pattern is useful for storing an arbitrary set of operations that can be executed at a later time. It has been used to support GUI action controls such as buttons and menus, recording macros, and supporting undo operations.

It is a behavioral design pattern where an object encapsulates the information needed to perform an operation at a later time. We will illustrate this pattern using a macro-like facility where a character can walk, run, or jump. A sequence of these actions can be saved and executed as needed.

Object-oriented solution to the command pattern

We start with the declaration of the Command interface as shown next. It has a single method, execute, whose intent is to execute some command and ...