Design Patterns Java™ Workbook

Summary

The COMMAND pattern lets you encapsulate a request in an object so that you can modify at runtime the method that a client will call. A classic example of the usefulness of COMMAND comes with menus. Menus know when to execute an action but don't know which method to call. COMMAND lets you parameterize a menu with the method calls that correspond to menu labels.

When you use a Java menu you can supply commands into a context that other developers have created. In other cases, you may take the role of the context provider, developing an environment in which to execute commands. Your environment may allow for parameterization of a service, as Java menus do. You may also provide hooks, or add extra value, such as timing an operation.

COMMAND ...