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Java > Open Source Codes > com > google > gwt > user > client > Command


1 /*
2  * Copyright 2006 Google Inc.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
5  * use this file except in compliance with the License. You may obtain a copy of
6  * the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13  * License for the specific language governing permissions and limitations under
14  * the License.
15  */
16 package com.google.gwt.user.client;
17
18 /**
19  * Encapsulates an action for later execution, often from a different context.
20  *
21  * <p>
22  * The Command interface provides a layer of separation between the code
23  * specifying some behavior and the code invoking that behavior. This separation
24  * aids in creating reusable code. For example, a
25  * {@link com.google.gwt.user.client.ui.MenuItem} can have a Command
26  * associated with it that it executes when the menu item is chosen by the user.
27  * Importantly, the code that constructed the Command to be executed when the
28  * menu item is invoked knows nothing about the internals of the MenuItem class
29  * and vice-versa.</p>
30  *
31  * <p> The Command interface is often implemented with an anonymous inner class.
32  * For example,
33  *
34  * <pre>
35  * Command sayHello = new Command() {
36  * public void execute() {
37  * Window.alert("Hello");
38  * }
39  * };
40  * sayHello.execute();
41  * </pre>
42  *
43  * </p>
44  */
45 public interface Command {
46
47   /**
48    * Causes the Command to perform its encapsulated behavior.
49    */
50   void execute();
51 }
52
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