package com.baeldung.nullobject; import java.util.Arrays; import java.util.List; public class RoutingHandler { public void handle(Iterable 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 messages = Arrays.asList(highPriorityMsg, mediumPriorityMsg, lowPriorityMsg, nullPriorityMsg); RoutingHandler routingHandler = new RoutingHandler(); routingHandler.handle(messages); } }