Mercurial > docs > DesignPatterns
comparison code/observer-example.java @ 33:97b57d24fd7b
added sample code; modified summary
author | meillo@marmaro.de |
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date | Fri, 10 Aug 2007 22:15:51 +0200 |
parents | |
children | b2cefbd90180 |
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32:3d6e01222e28 | 33:97b57d24fd7b |
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1 import java.util.Observable; | |
2 import java.util.Observer; | |
3 | |
4 public class MessageBoard extends Observable { | |
5 private String message; | |
6 | |
7 public String getMessage() { | |
8 return message; | |
9 } | |
10 | |
11 public void changeMessage(String message) { | |
12 this.message = message; | |
13 setChanged(); | |
14 notifyObservers(message); | |
15 } | |
16 | |
17 public static void main(String[] args) { | |
18 MessageBoard board = new MessageBoard(); | |
19 Student bob = new Student(); | |
20 Student joe = new Student(); | |
21 board.addObserver(bob); | |
22 board.addObserver(joe); | |
23 board.changeMessage("More Homework!"); | |
24 } | |
25 } | |
26 | |
27 class Student implements Observer { | |
28 public void update(Observable o, Object arg) { | |
29 System.out.println("Message board changed: " + arg); | |
30 } | |
31 } |