| /** |
| * 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.crunch.materialize.pobject; |
| |
| import java.util.Iterator; |
| |
| import org.apache.crunch.PCollection; |
| |
| /** |
| * A concrete implementation of {@link PObjectImpl} that uses the first element in the backing |
| * {@link PCollection} as the {@link org.apache.crunch.PObject} value. |
| * |
| * @param <T> The value type of this {@code PObject}. |
| */ |
| public class FirstElementPObject<T> extends PObjectImpl<T, T> { |
| |
| /** |
| * Constructs a new instance of this {@code PObject} implementation. |
| * |
| * @param collect The backing {@code PCollection} for this {@code PObject}. |
| */ |
| public FirstElementPObject(PCollection<T> collect) { |
| super(collect); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| public T process(Iterable<T> input) { |
| Iterator<T> itr = input.iterator(); |
| if (itr.hasNext()) { |
| return itr.next(); |
| } |
| return null; |
| } |
| } |