content: /*
   * 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.sdk.transforms;
  
  import org.apache.beam.sdk.values.KV;
  import org.apache.beam.sdk.values.PCollection;
  
  /**
   * {@code Values<V>} takes a {@code PCollection} of {@code KV<K, V>}s and returns a {@code
   * PCollection<V>} of the values.
   *
   * <p>Example of use:
   *
   * <pre>{@code
   * PCollection<KV<String, Long>> wordCounts = ...;
   * PCollection<Long> counts = wordCounts.apply(Values.<Long>create());
   * }</pre>
   *
   * <p>Each output element has the same timestamp and is in the same windows as its corresponding
   * input element, and the output {@code PCollection} has the same {@link
   * org.apache.beam.sdk.transforms.windowing.WindowFn} associated with it as the input.
   *
   * <p>See also {@link Keys}.
   *
   * @param <V> the type of the values in the input {@code PCollection}, and the type of the elements
   *     in the output {@code PCollection}
   */
  public class Values<V> extends PTransform<PCollection<? extends KV<?, V>>, PCollection<V>> {
    /**
     * Returns a {@code Values<V>} {@code PTransform}.
     *
     * @param <V> the type of the values in the input {@code PCollection}, and the type of the
     *     elements in the output {@code PCollection}
     */
    public static <V> Values<V> create() {
      return new Values<>();
    }
  
    private Values() {}
  
    @Override
    public PCollection<V> expand(PCollection<? extends KV<?, V>> in) {
      return in.apply(
          "Values",
          MapElements.via(
              new SimpleFunction<KV<?, V>, V>() {
                @Override
                public V apply(KV<?, V> kv) {
                  return kv.getValue();
                }
              }));
    }
  }
  