Java tutorial
//package com.java2s; /* * Copyright 2010 the original author or authors. * * Licensed 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. */ import java.util.*; public class Main { public static <T> Iterable<T> concat(Iterable<? extends T>... iterables) { return concat(Arrays.asList(iterables)); } public static <T> Iterable<T> concat(final List<Iterable<? extends T>> iterables) { return new Iterable<T>() { public Iterator<T> iterator() { return new Iterator<T>() { Iterator<? extends T> iter; int pos = 0; public boolean hasNext() { while (pos < iterables.size()) { if (iter == null) iter = iterables.get(pos).iterator(); if (iter.hasNext()) return true; iter = null; pos++; } return false; } public T next() { while (pos < iterables.size()) { if (iter == null) iter = iterables.get(pos).iterator(); if (iter.hasNext()) return iter.next(); iter = null; pos++; } throw new NoSuchElementException(); } public void remove() { throw new UnsupportedOperationException("remove"); } }; } }; } }