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POMediator pattern example: chat
 

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    <p>I read that chat is a sample of using of Mediator pattern. I wrote simple imitation of chat but I don't know how can I use mediator pattern in this situation. As I understand all my object already have loose coupling and Server class is similar to Mediator. Can someone show me using of Mediator pattern on my sample?</p> <pre><code>import java.util.ArrayList; import java.util.Collection; import java.util.List; import java.util.Observable; import java.util.Observer; import java.util.Random; import java.util.Timer; import java.util.TimerTask; public class Main1 { public static void main(String[] args) { final Server chatObserver = new Server(); chatObserver.addObserver(new Client("User1", chatObserver)); Timer t = new Timer(); t.schedule(new TimerTask() { @Override public void run() { chatObserver.addObserver(new Client("User2", chatObserver)); } }, 5); t.schedule(new TimerTask() { @Override public void run() { chatObserver.addObserver(new Client("User3", chatObserver)); } }, 10); } static class Client extends Observable implements Observer { private String name; private List&lt;Message&gt; chatHistoryToDisplay; private Timer timer = new Timer(); private Random random = new Random(); public Client(final String name, Observer o) { this.name = name; addObserver(o); chatHistoryToDisplay = new ArrayList&lt;Message&gt;(((Server) o).getChatHistory()); timer.scheduleAtFixedRate(new TimerTask() { @Override public void run() { int msg = random.nextInt(10); String str = name + " writed " + msg; System.out.println("\t"+str); setChanged(); notifyObservers(new Message(name,String.valueOf(msg))); } }, 0, 10000); } @Override public void update(Observable o, Object msg) { chatHistoryToDisplay.add((Message) msg); System.out.println("----------- "+name+" screen -----------"); for (int i=0;i&lt;chatHistoryToDisplay.size();i++) { Message m = chatHistoryToDisplay.get(i); System.out.println(m.toString()); } } } static class Server extends Observable implements Observer { private List&lt;Message&gt; chatHistory = new ArrayList&lt;Message&gt;(); @Override public void update(Observable arg0, Object msg) { chatHistory.add((Message) msg); setChanged(); notifyObservers(msg); } public Collection&lt;Message&gt; getChatHistory(){ return chatHistory; } } static class Message { private String author; private String message; public Message(String author, String message) { this.author = author; this.message = message; } @Override public String toString() { return author + ": " + message; } } } </code></pre> <p><strong>CONSOLE:</strong></p> <pre><code>User1 writed 3 ----------- User1 screen ----------- User1: 3 User2 writed 9 ----------- User2 screen ----------- User1: 3 User2: 9 ----------- User1 screen ----------- User1: 3 User2: 9 User3 writed 9 ----------- User3 screen ----------- User1: 3 User2: 9 User3: 9 ----------- User2 screen ----------- User1: 3 User2: 9 User3: 9 ----------- User1 screen ----------- User1: 3 User2: 9 User3: 9 </code></pre> <p>and so on...</p>
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