1 /* 2 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 package java.lang; 26 27 import java.util.Iterator; 28 import java.util.Objects; 29 import java.util.function.Consumer; 30 31 /** 32 * Implementing this interface allows an object to be the target of 33 * the "for-each loop" statement. See 34 * <strong> 35 * <a href="{@docRoot}/../technotes/guides/language/foreach.html">For-each Loop</a> 36 * </strong> 37 * 38 * @param <T> the type of elements returned by the iterator 39 * 40 * @since 1.5 41 * @jls 14.14.2 The enhanced for statement 42 */ 43 @FunctionalInterface 44 public interface Iterable<T> { 45 /** 46 * Returns an iterator over elements of type {@code T}. 47 * 48 * @return an Iterator. 49 */ 50 Iterator<T> iterator(); 51 52 /** 53 * Performs the given action on the contents of the {@code Iterable}, in the 54 * order elements occur when iterating, until all elements have been 55 * processed or the action throws an exception. Errors or runtime 56 * exceptions thrown by the action are relayed to the caller. 57 * 58 * @implSpec 59 * <p>The default implementation behaves as if: 60 * <pre>{@code 61 * for (T t : this) 62 * action.accept(t); 63 * }</pre> 64 * 65 * @param action The action to be performed for each element 66 * @throws NullPointerException if the specified action is null 67 * @since 1.8 68 */ 69 default void forEach(Consumer<? super T> action) { 70 Objects.requireNonNull(action); 71 for (T t : this) { 72 action.accept(t); 73 } 74 } 75 } 76