Encapsulates an action for later execution, often from a different context.

The Command interface provides a layer of separation between the code specifying some behavior and the code invoking that behavior. This separation aids in creating reusable code. For example, a {@link com.google.gwt.user.client.ui.MenuItem} can have a Command associated with it that it executes when the menu item is chosen by the user. Importantly, the code that constructed the Command to be executed when the menu item is invoked knows nothing about the internals of the MenuItem class and vice-versa.

The Command interface is often implemented with an anonymous inner class. For example,

Command sayHello = new Command() { public void execute() {

Window.alert("Hello");

} }; sayHello.execute();

abstract class Command<H> {

 /**
  * Causes the Command to perform its encapsulated behavior.
  */
 void execute();
}