151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski/* 23984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. 351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This code is free software; you can redistribute it and/or modify it 651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * under the terms of the GNU General Public License version 2 only, as 751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * published by the Free Software Foundation. Oracle designates this 851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * particular file as subject to the "Classpath" exception as provided 951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * by Oracle in the LICENSE file that accompanied this code. 1051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 1151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This code is distributed in the hope that it will be useful, but WITHOUT 1251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 1351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 1451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * version 2 for more details (a copy is included in the LICENSE file that 1551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * accompanied this code). 1651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 1751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * You should have received a copy of the GNU General Public License version 1851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 2 along with this work; if not, write to the Free Software Foundation, 1951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 2051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 2151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 2251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * or visit www.oracle.com if you need additional information or have any 2351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * questions. 2451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 2551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 2651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskipackage java.util; 2751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 283984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamathimport java.util.function.Consumer; 293984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath 3051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski/** 3151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * An iterator over a collection. {@code Iterator} takes the place of 3251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@link Enumeration} in the Java Collections Framework. Iterators 3351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * differ from enumerations in two ways: 3451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 3551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <ul> 3651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <li> Iterators allow the caller to remove elements from the 3751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * underlying collection during the iteration with well-defined 3851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * semantics. 3951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <li> Method names have been improved. 4051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * </ul> 4151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 4251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>This interface is a member of the 43d2449bb576ad1e3a3877364e5e1ae28625f69e35Yi Kong * <a href="{@docRoot}openjdk-redirect.html?v=8&path=/technotes/guides/collections/index.html"> 4451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Java Collections Framework</a>. 4551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 4651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param <E> the type of elements returned by this iterator 4751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 4851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @author Josh Bloch 4951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @see Collection 5051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @see ListIterator 5151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @see Iterable 5251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @since 1.2 5351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 5451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskipublic interface Iterator<E> { 5551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 5651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Returns {@code true} if the iteration has more elements. 5751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * (In other words, returns {@code true} if {@link #next} would 5851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * return an element rather than throwing an exception.) 5951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 6051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return {@code true} if the iteration has more elements 6151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 6251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski boolean hasNext(); 6351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 6451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 6551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Returns the next element in the iteration. 6651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 6751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return the next element in the iteration 6851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws NoSuchElementException if the iteration has no more elements 6951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 7051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski E next(); 7151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 7251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 7351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Removes from the underlying collection the last element returned 7451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * by this iterator (optional operation). This method can be called 7551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * only once per call to {@link #next}. The behavior of an iterator 7651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * is unspecified if the underlying collection is modified while the 7751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * iteration is in progress in any way other than by calling this 7851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * method. 7951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 803984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * @implSpec 813984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * The default implementation throws an instance of 823984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * {@link UnsupportedOperationException} and performs no other action. 833984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * 8451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws UnsupportedOperationException if the {@code remove} 8551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * operation is not supported by this iterator 8651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 8751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalStateException if the {@code next} method has not 8851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * yet been called, or the {@code remove} method has already 8951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * been called after the last call to the {@code next} 9051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * method 9151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 923984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath default void remove() { 933984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath throw new UnsupportedOperationException("remove"); 943984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath } 953984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath 963984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath /** 973984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * Performs the given action for each remaining element until all elements 983984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * have been processed or the action throws an exception. Actions are 993984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * performed in the order of iteration, if that order is specified. 1003984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * Exceptions thrown by the action are relayed to the caller. 1013984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * 1023984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * @implSpec 1033984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * <p>The default implementation behaves as if: 1043984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * <pre>{@code 1053984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * while (hasNext()) 1063984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * action.accept(next()); 1073984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * }</pre> 1083984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * 1093984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * @param action The action to be performed for each element 1103984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * @throws NullPointerException if the specified action is null 1113984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath * @since 1.8 1123984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath */ 1133984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath default void forEachRemaining(Consumer<? super E> action) { 1143984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath Objects.requireNonNull(action); 1153984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath while (hasNext()) 1163984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath action.accept(next()); 1173984cdba314a0f7b0587000dec99ff26fd9bcbb5Narayan Kamath } 11851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski} 119