Merge pull request #38029 from Subramanya-Veeregowda/pico-wordcount-example

Added PicoWordCount example to java Examples

Author: stankiewicz

examples/java/src/main/java/org/apache/beam/examples/PicoWordCount.java

@@ -0,0 +1,56 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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
+ *
+ *     http://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 org.apache.beam.examples;
+
+import java.util.Arrays;
+import org.apache.beam.sdk.Pipeline;
+import org.apache.beam.sdk.io.TextIO;
+import org.apache.beam.sdk.transforms.Count;
+import org.apache.beam.sdk.transforms.Filter;
+import org.apache.beam.sdk.transforms.FlatMapElements;
+import org.apache.beam.sdk.transforms.MapElements;
+import org.apache.beam.sdk.values.KV;
+import org.apache.beam.sdk.values.TypeDescriptors;
+
+/**
+ * A minimal "pico" example of WordCount.
+ *
+ * <p>This is a simplified version of MinimalWordCount with fewer concepts.
+ */
+public class PicoWordCount {
+
+  public static void main(String[] args) {
+
+    Pipeline p = Pipeline.create();
+
+    p.apply("ReadLines", TextIO.read().from("input.txt"))
+        .apply(
+            "ExtractWords",
+            FlatMapElements.into(TypeDescriptors.strings())
+                .via((String line) -> Arrays.asList(line.split("\\W+"))))
+        .apply("FilterEmptyWords", Filter.by((String word) -> !word.isEmpty()))
+        .apply("CountWords", Count.perElement())
+        .apply(
+            "FormatResults",
+            MapElements.into(TypeDescriptors.strings())
+                .via((KV<String, Long> kv) -> kv.getKey() + ": " + kv.getValue()))
+        .apply("WriteResults", TextIO.write().to("output"));
+
+    p.run().waitUntilFinish();
+  }
+}

sdks/java/maven-archetypes/starter/src/main/resources/archetype-resources/src/main/java/StarterPipeline.java

@@ -51,16 +51,19 @@ public static void main(String[] args) {
         PipelineOptionsFactory.fromArgs(args).withValidation().create());
 
     p.apply(Create.of("Hello", "World"))
-    .apply(MapElements.via(new SimpleFunction<String, String>() {
-      @Override
-      public String apply(String input) {
-        return input.toUpperCase();
-      }
-    }))
+    .apply(
+      MapElements.via(
+        new SimpleFunction<String, String>() {
+            @Override
+            public String apply(String input) 
+            {
+                 return input.toUpperCase();
+            }
+         }))
     .apply(ParDo.of(new DoFn<String, Void>() {
       @ProcessElement
-      public void processElement(ProcessContext c)  {
-        LOG.info(c.element());
+      public void processElement(@Element String element)  {
+        LOG.info(element);
       }
     }));