Update CreateTopicAndPublishMessages.java (#3249)

Add the publisher error handler sample. As requested, the error handling part in the publishing quickstart sample is now removed.

Author: chenyumic

google-cloud-examples/src/main/java/com/google/cloud/examples/pubsub/snippets/CreateTopicAndPublishMessages.java

@@ -17,7 +17,9 @@
 package com.google.cloud.examples.pubsub.snippets;
 
 import com.google.api.core.ApiFuture;
+import com.google.api.core.ApiFutureCallback;
 import com.google.api.core.ApiFutures;
+import com.google.api.gax.rpc.ApiException;
 import com.google.cloud.pubsub.v1.Publisher;
 import com.google.cloud.pubsub.v1.TopicAdminClient;
 import com.google.protobuf.ByteString;
@@ -78,6 +80,54 @@ public static void publishMessages() throws Exception {
     // [END pubsub_publish]
   }
 
+  public static void publishMessagesWithErrorHandler() throws Exception {
+    // [START pubsub_publish_error_handler]
+    ProjectTopicName topicName = ProjectTopicName.of("my-project-id", "my-topic-id");
+    Publisher publisher = null;
+
+    try {
+      // Create a publisher instance with default settings bound to the topic
+      publisher = Publisher.newBuilder(topicName).build();
+
+      List<String> messages = Arrays.asList("first message", "second message");
+
+      for (final String message : messages) {
+        ByteString data = ByteString.copyFromUtf8(message);
+        PubsubMessage pubsubMessage = PubsubMessage.newBuilder().setData(data).build();
+
+        // Once published, returns a server-assigned message id (unique within the topic)
+        ApiFuture<String> future = publisher.publish(pubsubMessage);
+
+        // Add an asynchronous callback to handle success / failure
+        ApiFutures.addCallback(future, new ApiFutureCallback<String>() {
+
+          @Override
+          public void onFailure(Throwable throwable) {
+            if (throwable instanceof ApiException) {
+              ApiException apiException = ((ApiException) throwable);
+              // details on the API exception
+              System.out.println(apiException.getStatusCode().getCode());
+              System.out.println(apiException.isRetryable());
+            }
+            System.out.println("Error publishing message : " + message);
+          }
+
+          @Override
+          public void onSuccess(String messageId) {
+            // Once published, returns server-assigned message ids (unique within the topic)
+            System.out.println(messageId);
+          }
+        });
+      }
+    } finally {
+      if (publisher != null) {
+        // When finished with the publisher, shutdown to free up resources.
+        publisher.shutdown();
+      }
+    }
+    // [END pubsub_publish_error_handler]
+  }
+  
   public static void main(String... args) throws Exception {
     createTopic();
     publishMessages();