ueb07 b)

ueb07_news_example_b/src/client/Client.java

@@ -4,10 +4,19 @@ import model.Article;
 import model.Image;
 import model.NewsCollection;
 
-public class Client {
-	
+import java.util.Observable;
+import java.util.Observer;
+
+public class Client implements Observer {
+
 	public static void main(String[] args) {
+		Client client = new Client();
+		client.run();
+	}
+	
+	public void run() {
 		NewsCollection masterCollection = new NewsCollection("Daily news");
+		masterCollection.addObserver(this);
 
 		Article changedArticle = new Article("Harder, Better, Faster, Stronger. Doping controls loosened","ups");
 
@@ -23,9 +32,18 @@ public class Client {
 		System.out.print(masterCollection.getOverviewInformation());
 		System.out.println("\n===Contents===\n");
 		System.out.print(masterCollection.getDetailedInformation());
+
+		masterCollection.addObserver(this);
+
 		System.out.println("\n===After change===\n");
 
 		changedArticle.setTitle("Harder, Better, Faster, Stronger? Doping controls loosened");
 		masterCollection.addItem(new Image("A tasty cat", 640, 480, "alf"));
 	}
+
+	@Override
+	public void update(Observable o, Object arg) {
+		System.out.println("### UPDATE ###");
+		System.out.println(arg);
+	}
 }

ueb07_news_example_b/src/model/NewsCollection.java

@@ -1,16 +1,29 @@
 package model;
 
-import java.util.LinkedList;
-import java.util.List;
+import java.util.*;
 
 public class NewsCollection extends NewsItem {
-	
+	private Set<Observer> observers = new HashSet<>();
 	private List<NewsItem> newsItems = new LinkedList<NewsItem>();
 			
 	public NewsCollection(String topic) {
 		this.title = topic;
 	}
-	
+
+	@Override
+	public synchronized void addObserver(Observer o) {
+		super.addObserver(o);
+		observers.add(o);
+		newsItems.forEach(i -> i.addObserver(o));
+	}
+
+	@Override
+	public synchronized void deleteObserver(Observer o) {
+		super.deleteObserver(o);
+		observers.remove(o);
+		newsItems.forEach(i -> i.deleteObserver(o));
+	}
+
 	/**
 	 * Get the list of items stored in this collection.
 	 * @return items stored in this collection
@@ -25,7 +38,11 @@ public class NewsCollection extends NewsItem {
 	 * @return this collection (enables method chaining)
 	 */
 	public NewsCollection addItem(NewsItem item) {
+		String updateNotification = getTitle() + "\n+ " + item.getTitle() + "\n";
 		newsItems.add(item);
+		setChanged();
+		notifyObservers(updateNotification);
+		observers.forEach(item::addObserver);
 		return this;
 	}
 	
@@ -54,5 +71,5 @@ public class NewsCollection extends NewsItem {
 			builder.append("\n");
 		}
 		return builder.toString();
-	}	
+	}
 }

ueb07_news_example_b/src/model/NewsItem.java

@@ -1,6 +1,8 @@
 package model;
 
-public abstract class NewsItem {
+import java.util.Observable;
+
+public abstract class NewsItem extends Observable {
 
 	protected String title;
 
@@ -17,7 +19,10 @@ public abstract class NewsItem {
 	}
 	
 	public void setTitle(String newTitle) {
+		String updateNotification = "- " + title + "\n+ " + newTitle + "\n";
 		title = newTitle;
+		setChanged();
+		notifyObservers(updateNotification);
 	}
 
 	/**