Add Java PubSub Read with dead letter topic pipeline example

Java/src/main/java/pubsub/ReadWithDeadLetterTopicPubSub.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package pubsub;
+
+import org.apache.beam.sdk.Pipeline;
+import org.apache.beam.sdk.coders.StringUtf8Coder;
+import org.apache.beam.sdk.io.gcp.pubsub.PubsubIO;
+import org.apache.beam.sdk.options.Description;
+import org.apache.beam.sdk.options.PipelineOptions;
+import org.apache.beam.sdk.options.PipelineOptionsFactory;
+import org.apache.beam.sdk.options.Validation;
+import org.apache.beam.sdk.transforms.SimpleFunction;
+import org.apache.beam.sdk.values.TypeDescriptors;
+
+import java.nio.charset.StandardCharsets;
+
+public class ReadWithDeadLetterTopicPubSub {
+
+    public static final String ID_EXAMPLE_SUFFIX = "id=";
+
+    /** Pipeline options for read from Google Cloud Pub/Sub. */
+    public interface ReadPubSubOptions extends PipelineOptions {
+        @Description("Google Cloud Pub/Sub subscription to read from")
+        @Validation.Required
+        String getSubscription();
+
+        void setSubscription(String subscription);
+
+        @Description("Google Cloud Pub/Sub dead letter topic to write errors to")
+        @Validation.Required
+        String getDeadLetterTopic();
+
+        void setDeadLetterTopic(String deadLetterTopic);
+    }
+
+    public static void main(String[] args) {
+        ReadPubSubOptions options =
+            PipelineOptionsFactory.fromArgs(args).withValidation().as(ReadPubSubOptions.class);
+
+        Pipeline p = Pipeline.create(options);
+
+        p.apply(
+            "Read from Pub/Sub",
+            PubsubIO.readStrings()
+                .fromSubscription(options.getSubscription())
+                .withDeadLetterTopic(options.getDeadLetterTopic())
+                .withCoderAndParseFn(
+                    StringUtf8Coder.of(),
+                    SimpleFunction.fromSerializableFunctionWithOutputType(
+                        message -> {
+                            String str = new String(message.getPayload(), StandardCharsets.UTF_8);
+
+                            //Example check if it is correct string
+                            if (!str.contains(ID_EXAMPLE_SUFFIX)) {
+                                throw new RuntimeException("This message will be delivered to dead letter topic");
+                            }
+                            return str;
+                        },
+                        TypeDescriptors.strings())));
+        p.run();
+    }
+}