| /* |
| * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.util; |
| |
| /** |
| * An iterator for lists that allows the programmer |
| * to traverse the list in either direction, modify |
| * the list during iteration, and obtain the iterator's |
| * current position in the list. A {@code ListIterator} |
| * has no current element; its <I>cursor position</I> always |
| * lies between the element that would be returned by a call |
| * to {@code previous()} and the element that would be |
| * returned by a call to {@code next()}. |
| * An iterator for a list of length {@code n} has {@code n+1} possible |
| * cursor positions, as illustrated by the carets ({@code ^}) below: |
| * <PRE> |
| * Element(0) Element(1) Element(2) ... Element(n-1) |
| * cursor positions: ^ ^ ^ ^ ^ |
| * </PRE> |
| * Note that the {@link #remove} and {@link #set(Object)} methods are |
| * <i>not</i> defined in terms of the cursor position; they are defined to |
| * operate on the last element returned by a call to {@link #next} or |
| * {@link #previous()}. |
| * |
| * <p>This interface is a member of the |
| * <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
| * Java Collections Framework</a>. |
| * |
| * @author Josh Bloch |
| * @see Collection |
| * @see List |
| * @see Iterator |
| * @see Enumeration |
| * @see List#listIterator() |
| * @since 1.2 |
| */ |
| public interface ListIterator<E> extends Iterator<E> { |
| // Query Operations |
| |
| /** |
| * Returns {@code true} if this list iterator has more elements when |
| * traversing the list in the forward direction. (In other words, |
| * returns {@code true} if {@link #next} would return an element rather |
| * than throwing an exception.) |
| * |
| * @return {@code true} if the list iterator has more elements when |
| * traversing the list in the forward direction |
| */ |
| boolean hasNext(); |
| |
| /** |
| * Returns the next element in the list and advances the cursor position. |
| * This method may be called repeatedly to iterate through the list, |
| * or intermixed with calls to {@link #previous} to go back and forth. |
| * (Note that alternating calls to {@code next} and {@code previous} |
| * will return the same element repeatedly.) |
| * |
| * @return the next element in the list |
| * @throws NoSuchElementException if the iteration has no next element |
| */ |
| E next(); |
| |
| /** |
| * Returns {@code true} if this list iterator has more elements when |
| * traversing the list in the reverse direction. (In other words, |
| * returns {@code true} if {@link #previous} would return an element |
| * rather than throwing an exception.) |
| * |
| * @return {@code true} if the list iterator has more elements when |
| * traversing the list in the reverse direction |
| */ |
| boolean hasPrevious(); |
| |
| /** |
| * Returns the previous element in the list and moves the cursor |
| * position backwards. This method may be called repeatedly to |
| * iterate through the list backwards, or intermixed with calls to |
| * {@link #next} to go back and forth. (Note that alternating calls |
| * to {@code next} and {@code previous} will return the same |
| * element repeatedly.) |
| * |
| * @return the previous element in the list |
| * @throws NoSuchElementException if the iteration has no previous |
| * element |
| */ |
| E previous(); |
| |
| /** |
| * Returns the index of the element that would be returned by a |
| * subsequent call to {@link #next}. (Returns list size if the list |
| * iterator is at the end of the list.) |
| * |
| * @return the index of the element that would be returned by a |
| * subsequent call to {@code next}, or list size if the list |
| * iterator is at the end of the list |
| */ |
| int nextIndex(); |
| |
| /** |
| * Returns the index of the element that would be returned by a |
| * subsequent call to {@link #previous}. (Returns -1 if the list |
| * iterator is at the beginning of the list.) |
| * |
| * @return the index of the element that would be returned by a |
| * subsequent call to {@code previous}, or -1 if the list |
| * iterator is at the beginning of the list |
| */ |
| int previousIndex(); |
| |
| |
| // Modification Operations |
| |
| /** |
| * Removes from the list the last element that was returned by {@link |
| * #next} or {@link #previous} (optional operation). This call can |
| * only be made once per call to {@code next} or {@code previous}. |
| * It can be made only if {@link #add} has not been |
| * called after the last call to {@code next} or {@code previous}. |
| * |
| * @throws UnsupportedOperationException if the {@code remove} |
| * operation is not supported by this list iterator |
| * @throws IllegalStateException if neither {@code next} nor |
| * {@code previous} have been called, or {@code remove} or |
| * {@code add} have been called after the last call to |
| * {@code next} or {@code previous} |
| */ |
| void remove(); |
| |
| /** |
| * Replaces the last element returned by {@link #next} or |
| * {@link #previous} with the specified element (optional operation). |
| * This call can be made only if neither {@link #remove} nor {@link |
| * #add} have been called after the last call to {@code next} or |
| * {@code previous}. |
| * |
| * @param e the element with which to replace the last element returned by |
| * {@code next} or {@code previous} |
| * @throws UnsupportedOperationException if the {@code set} operation |
| * is not supported by this list iterator |
| * @throws ClassCastException if the class of the specified element |
| * prevents it from being added to this list |
| * @throws IllegalArgumentException if some aspect of the specified |
| * element prevents it from being added to this list |
| * @throws IllegalStateException if neither {@code next} nor |
| * {@code previous} have been called, or {@code remove} or |
| * {@code add} have been called after the last call to |
| * {@code next} or {@code previous} |
| */ |
| void set(E e); |
| |
| /** |
| * Inserts the specified element into the list (optional operation). |
| * The element is inserted immediately before the element that |
| * would be returned by {@link #next}, if any, and after the element |
| * that would be returned by {@link #previous}, if any. (If the |
| * list contains no elements, the new element becomes the sole element |
| * on the list.) The new element is inserted before the implicit |
| * cursor: a subsequent call to {@code next} would be unaffected, and a |
| * subsequent call to {@code previous} would return the new element. |
| * (This call increases by one the value that would be returned by a |
| * call to {@code nextIndex} or {@code previousIndex}.) |
| * |
| * @param e the element to insert |
| * @throws UnsupportedOperationException if the {@code add} method is |
| * not supported by this list iterator |
| * @throws ClassCastException if the class of the specified element |
| * prevents it from being added to this list |
| * @throws IllegalArgumentException if some aspect of this element |
| * prevents it from being added to this list |
| */ |
| void add(E e); |
| } |
