new commit

Author: Aleksandr Gromov

java8Module/src/main/java/patterns/observer/Client.java

@@ -0,0 +1,22 @@
+package patterns.observer;
+
+public class Client {
+    public static void main(String[] args) {
+        DataStore dataStore = new DataStore();
+        Screen screen = new Screen();
+
+        // add Observer screen
+        dataStore.addObserver(screen);
+
+        dataStore.setData("Hi");
+        dataStore.notifyObservers();
+        dataStore.setData("Hi1");
+        dataStore.notifyObservers();
+        dataStore.setData("Hi2");
+        dataStore.setData("Hi3");
+        dataStore.setData("Hi4");
+        dataStore.notifyObservers();
+
+        dataStore.deleteObserver(screen);
+    }
+}

java8Module/src/main/java/patterns/observer/DataStore.java

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+package patterns.observer;
+
+import java.util.Observable;
+
+public class DataStore extends Observable {
+    private String data;
+    public String getData() {
+        return data;
+    }
+    public void setData(String data) {
+        this.data = data;
+        //mark the observable as changed
+        setChanged();
+    }
+}

java8Module/src/main/java/patterns/observer/Screen.java

@@ -0,0 +1,11 @@
+package patterns.observer;
+
+import java.util.Observable;
+import java.util.Observer;
+
+public class Screen implements Observer {
+    @Override
+    public void update(Observable o, Object arg) {
+        System.out.println("Changed to " + ((DataStore)o).getData());
+    }
+}