Added Comments and Feedback

amit2103 · amit2103 · commit 19f5966cb9b5 · 2015-10-07T20:37:45.000+05:30
diff --git a/monostate/src/main/java/com/iluwatar/monostate/App.java b/monostate/src/main/java/com/iluwatar/monostate/App.java
@@ -1,11 +1,35 @@
 package com.iluwatar.monostate;
 
+
+
+/**
+ * 
+ * The MonoState pattern ensures that all instances of the class will have the same state. This can
+ * be used a direct replacement of the Singleton pattern.
+ * 
+ * <p>
+ * In the following example, The {@link LoadBalancer} class represents the app's logic. It contains
+ * a series of Servers, which can handle requests of type {@link Request}. Two instances of
+ * LoadBalacer are created. When a request is made to a server via the first LoadBalancer the state
+ * change in the first load balancer affects the second. So if the first LoadBalancer selects the
+ * Server 1, the second LoadBalancer on a new request will select the Second server. If a third
+ * LoadBalancer is created and a new request is made to it, then it will select the third server as
+ * the second load balancer has already selected the second server.
+ * <p>
+ * .
+ * 
+ */
 public class App {
-	public static void main(String[] args) {
-		LoadBalancer loadBalancer1 = new LoadBalancer();
-		LoadBalancer loadBalancer2 = new LoadBalancer();
-		loadBalancer1.serverequest(new Request("Hello"));
-		loadBalancer2.serverequest(new Request("Hello World"));
-	}
+  /**
+   * Program entry point
+   * 
+   * @param args command line args
+   */
+  public static void main(String[] args) {
+    LoadBalancer loadBalancer1 = new LoadBalancer();
+    LoadBalancer loadBalancer2 = new LoadBalancer();
+    loadBalancer1.serverequest(new Request("Hello"));
+    loadBalancer2.serverequest(new Request("Hello World"));
+  }
 
 }
diff --git a/monostate/src/main/java/com/iluwatar/monostate/LoadBalancer.java b/monostate/src/main/java/com/iluwatar/monostate/LoadBalancer.java
@@ -3,6 +3,14 @@
 import java.util.ArrayList;
 import java.util.List;
 
+/**
+ * The LoadBalancer class. This implements the MonoState pattern. It holds a series of servers. Upon
+ * receiving a new Request, it delegates the call to the servers in a Round Robin Fashion. Since all
+ * instances of the class share the same state, all instances will delegate to the same server on
+ * receiving a new Request.
+ * 
+ */
+
 public class LoadBalancer {
   private static List<Server> servers = new ArrayList<>();
   private static int id = 0;
@@ -27,13 +35,18 @@ public final int getNoOfServers() {
     return servers.size();
   }
 
+  public static int getLastServedId() {
+    return lastServedId;
+  }
+
   public void serverequest(Request request) {
     if (lastServedId >= servers.size()) {
       lastServedId = 0;
     }
     Server server = servers.get(lastServedId++);
     server.serve(request);
   }
+  
 
 
 }
diff --git a/monostate/src/main/java/com/iluwatar/monostate/Request.java b/monostate/src/main/java/com/iluwatar/monostate/Request.java
@@ -1,5 +1,11 @@
 package com.iluwatar.monostate;
 
+/**
+ * 
+ * The Request class. A {@link Server} can handle an instance of a Request. 
+ * 
+ */
+
 public class Request {
   public final String value;
 
diff --git a/monostate/src/main/java/com/iluwatar/monostate/Server.java b/monostate/src/main/java/com/iluwatar/monostate/Server.java
@@ -1,21 +1,31 @@
 package com.iluwatar.monostate;
 
+/**
+ * 
+ * The Server class. Each Server sits behind a LoadBalancer which delegates the call to the 
+ * servers in a simplistic Round Robin fashion.
+ *
+ */
 public class Server {
   public final String host;
   public final int port;
   public final int id;
+
   public Server(String host, int port, int id) {
     this.host = host;
     this.port = port;
     this.id = id;
   }
+
   public String getHost() {
     return host;
   }
+
   public int getPort() {
     return port;
   }
+
   public final void serve(Request request) {
-    System.out.println("Server ID "+id + "  processed request with value  "+request.value);
+    System.out.println("Server ID " + id + "  processed request with value  " + request.value);
   }
 }
diff --git a/monostate/src/test/java/com/iluwatar/monostate/AppTest.java b/monostate/src/test/java/com/iluwatar/monostate/AppTest.java
@@ -0,0 +1,26 @@
+package com.iluwatar.monostate;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class AppTest {
+
+  @Test
+  public void testSameStateAmonstAllInstances() {
+    LoadBalancer balancer = new LoadBalancer();
+    LoadBalancer balancer2 = new LoadBalancer();
+    balancer.addServer(new Server("localhost", 8085, 6));
+    // Both should have the same number of servers.
+    Assert.assertTrue(balancer.getNoOfServers() == balancer2.getNoOfServers());
+    // Both Should have the same LastServedId
+    Assert.assertTrue(balancer.getLastServedId() == balancer2.getLastServedId());
+  }
+  
+  @Test
+  public void testMain() {
+    String[] args = {};
+    App.main(args);
+    Assert.assertTrue(LoadBalancer.getLastServedId() == 2);
+  }
+
+}
