BAEL-2755: Added design-patterns-2 module

patterns/design-patterns-2/src/main/java/com/baeldung/nullobject/RoutingHandler.java

@@ -0,0 +1,30 @@
+package com.baeldung.nullobject;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class RoutingHandler {
+
+    public void handle(Iterable<Message> messages){
+        for (Message msg : messages) {
+            Router router = RouterFactory.getRouterForMessage(msg);
+            router.route(msg);
+        }
+    }
+
+    public static void main(String[] args) {
+        Message highPriorityMsg = new Message("Alert!", "high");
+        Message mediumPriorityMsg = new Message("Warning!", "medium");
+        Message lowPriorityMsg = new Message("Take a look!", "low");
+        Message nullPriorityMsg = new Message("Take a look!", null);
+
+        List<Message> messages = Arrays.asList(highPriorityMsg,
+                mediumPriorityMsg,
+                lowPriorityMsg,
+                nullPriorityMsg);
+
+        RoutingHandler routingHandler = new RoutingHandler();
+        routingHandler.handle(messages);
+
+    }
+}