Updated Announcer to use generics

npathai · npathai · commit 7d490a9cd46b · 2016-09-07T02:02:06.000+05:30
diff --git a/proxy/src/main/java/com/iluwatar/proxy/example2/Announcer.java b/proxy/src/main/java/com/iluwatar/proxy/example2/Announcer.java
@@ -3,19 +3,20 @@
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Proxy;
+import java.util.EventListener;
 import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
 
-public class Announcer {
+public class Announcer<T extends EventListener> {
 
-  private HealthMonitor proxy;
-  private List<HealthMonitor> listeners = new CopyOnWriteArrayList<>();
+  private T proxy;
+  private List<T> listeners = new CopyOnWriteArrayList<>();
 
-  public Announcer(Class<HealthMonitor> listenerType) {
+  public Announcer(Class<T> listenerType) {
     proxy = createProxy(listenerType);
   }
 
-  private HealthMonitor createProxy(Class<HealthMonitor> listenerType) {
+  private T createProxy(Class<T> listenerType) {
     return listenerType.cast(Proxy.newProxyInstance(listenerType.getClassLoader(), 
         new Class<?>[] {listenerType}, (proxy, method, args) -> {
           invokeAll(method, args);
@@ -24,7 +25,7 @@ private HealthMonitor createProxy(Class<HealthMonitor> listenerType) {
   }
 
   private void invokeAll(Method method, Object[] args) {
-    for (HealthMonitor listener : listeners) {
+    for (T listener : listeners) {
       try {
         method.invoke(listener, args);
       } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
@@ -33,15 +34,19 @@ private void invokeAll(Method method, Object[] args) {
     }
   }
 
-  public void registerListener(HealthMonitor listener) {
+  public void registerListener(T listener) {
     listeners.add(listener);
   }
 
-  public HealthMonitor announce() {
+  public T announce() {
     return proxy;
   }
 
-  public void removeListener(HealthMonitor listener) {
+  public void removeListener(T listener) {
     listeners.remove(listener);
   }
+
+  public static <T extends EventListener> Announcer<T> to(Class<T> listenerType) {
+    return new Announcer<>(listenerType);
+  }
 }
diff --git a/proxy/src/main/java/com/iluwatar/proxy/example2/EndPoint.java b/proxy/src/main/java/com/iluwatar/proxy/example2/EndPoint.java
@@ -3,7 +3,7 @@
 public class EndPoint {
 
   private final String name;
-  private final Announcer healthMonitors = new Announcer(HealthMonitor.class);
+  private final Announcer<HealthMonitor> healthMonitors = Announcer.to(HealthMonitor.class);
   
   public EndPoint(String name) {
     this.name = name;
diff --git a/proxy/src/main/java/com/iluwatar/proxy/example2/HealthMonitor.java b/proxy/src/main/java/com/iluwatar/proxy/example2/HealthMonitor.java
@@ -1,6 +1,8 @@
 package com.iluwatar.proxy.example2;
 
-public interface HealthMonitor {
+import java.util.EventListener;
+
+public interface HealthMonitor extends EventListener {
 
   void disconnected(EndPoint endPoint);
 
diff --git a/proxy/src/test/java/com/iluwatar/proxy/example2/AnnouncerTest.java b/proxy/src/test/java/com/iluwatar/proxy/example2/AnnouncerTest.java
@@ -16,7 +16,7 @@ public class AnnouncerTest {
   private EndPoint endPoint = mock(EndPoint.class);
   private HealthMonitor monitor1 = mock(HealthMonitor.class);
   private HealthMonitor monitor2 = mock(HealthMonitor.class);
-  private Announcer announcer = new Announcer(HealthMonitor.class);
+  private Announcer<HealthMonitor> announcer = Announcer.to(HealthMonitor.class);
   
   @Before
   public void setUp() {
