Java tutorial
/* * 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.jclouds.functions; import javax.inject.Singleton; import com.google.common.base.Function; import com.google.common.collect.Iterables; /** * @author Adrian Cole */ @Singleton public class OnlyElementOrNull<T> implements Function<Iterable<T>, T> { @Override public T apply(Iterable<T> arg0) { if (arg0 == null || Iterables.size(arg0) == 0) return null; return Iterables.getOnlyElement(arg0); } }