1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 package org.apache.giraph.utils; 20 21 import java.util.Collections; 22 23 import java.util.Iterator; 24 25 /** 26 * Singleton class for empty iterables. 27 * 28 * @param <T> Element type 29 */ 30 public class EmptyIterable<T> implements Iterable<T> { 31 /** Singleton empty iterable */ 32 private static final EmptyIterable EMPTY_ITERABLE = new EmptyIterable(); 33 34 /** 35 * Get the singleton empty iterable 36 * 37 * @param <T> Element type 38 * @return Singleton empty iterable 39 */ 40 public static <T> Iterable<T> get() { 41 return (Iterable<T>) EMPTY_ITERABLE; 42 } 43 44 @Override 45 public Iterator<T> iterator() { 46 return Collections.emptyIterator(); 47 } 48 } 49