try to generify the observer pattern

src/main/java/_9/_3/Ship.java

@@ -1,6 +1,8 @@
 package _9._3;
 
-public class Ship extends Observable {
+import _9._3.observer.Observable;
+
+public class Ship extends Observable<Ship, ShipEvent> {
     private boolean sailsSet = false;
     private boolean cannonsLoaded = false;
     private int heading = 0;
@@ -13,6 +15,10 @@ public class Ship extends Observable {
         }
     }
 
+    public boolean isSailsSet() {
+        return this.sailsSet;
+    }
+
     public void strikeSails() {
         if (sailsSet) {
             sailsSet = false;
@@ -37,6 +43,10 @@ public class Ship extends Observable {
         }
     }
 
+    public boolean isCannonsLoaded() {
+        return this.cannonsLoaded;
+    }
+
     public void turnLeft() {
         heading = (heading - 90) % 180;
         this.setChanged();
@@ -48,4 +58,8 @@ public class Ship extends Observable {
         this.setChanged();
         notifyObservers(ShipEvent.TURN_RIGHT);
     }
+
+    public int getHeading() {
+        return this.heading;
+    }
 }

src/main/java/_9/_3/ShipEvent.java

@@ -1,6 +1,6 @@
 package _9._3;
 
-import java.util.Random;
+import java.util.concurrent.ThreadLocalRandom;
 
 public enum ShipEvent {
 	
@@ -13,7 +13,6 @@ public enum ShipEvent {
 	TURN_RIGHT;
 
 	public static ShipEvent getRandomShipEvent() {
-		Random random = new Random();
+		return values()[ThreadLocalRandom.current().nextInt(values().length)];
-		return values()[random.nextInt(values().length)];
 	}
 }

src/main/java/_9/_3/ShipLog.java

@@ -1,11 +1,10 @@
 package _9._3;
 
-import provided._9.Observer;
+import _9._3.observer.Observer;
 
-public class ShipLog implements Observer {
+public class ShipLog implements Observer<Ship, ShipEvent> {
-    private int heading = 0;
     @Override
-    public void update(Observable who, ShipEvent what) {
+    public void update(Ship who, ShipEvent what) {
         switch (what) {
             case SET_SAILS:
                 System.out.println("Sails set.");
@@ -20,12 +19,10 @@ public class ShipLog implements Observer {
                 System.out.println("Cannons fired.");
                 break;
             case TURN_LEFT:
-                heading = (heading - 90) % 180;
+                System.out.println("Turned left. New heading " + who.getHeading() + " degrees.");
-                System.out.println("Turned left. New heading " + heading + " degrees.");
                 break;
             case TURN_RIGHT:
-                heading = (heading + 90) % 180;
+                System.out.println("Turned right. New heading " + who.getHeading() + " degrees.");
-                System.out.println("Turned right. New heading " + heading + " degrees.");
                 break;
         }
     }

src/main/java/_9/_3/observer/Observable.java

@@ -1,19 +1,17 @@
-package _9._3;
+package _9._3.observer;
-
-import provided._9.Observer;
 
 import java.util.ArrayList;
 import java.util.List;
 
-public abstract class Observable {
+public abstract class Observable<Who extends Observable<Who, What>, What> {
-    private List<Observer> observers = new ArrayList<>();
+    private List<Observer<Who, What>> observers = new ArrayList<>();
     private boolean changed = false;
 
-    public void addObserver(Observer o) {
+    public void addObserver(Observer<Who, What> o) {
         this.observers.add(o);
     }
 
-    public void removeObserver(Observer o) {
+    public void removeObserver(Observer<Who, What> o) {
         this.observers.remove(o);
     }
 
@@ -29,10 +27,10 @@ public abstract class Observable {
         return changed;
     }
 
-    public void notifyObservers(ShipEvent what) {
+    public void notifyObservers(What what) {
         if (this.isChanged()) {
-            for (Observer observer : observers) {
+            for (Observer<Who, What> observer : observers) {
-                observer.update(this, what);
+                observer.update((Who) this, what);
             }
             this.clearChanged();
         }

src/main/java/_9/_3/observer/Observer.java

@@ -0,0 +1,5 @@
+package _9._3.observer;
+
+public interface Observer<Who extends Observable<Who, What>, What> {
+	void update(Who who, What what);
+}

src/main/java/provided/_9/Observer.java

@@ -1,10 +0,0 @@
-package provided._9;
-
-import _9._3.Observable;
-import _9._3.ShipEvent;
-
-public interface Observer {
-	
-	void update(Observable who, ShipEvent what);
-
-}