/* Iterator.java -- Interface for iterating over collections Copyright (C) 1998, 2001, 2005 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath 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 for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version. */ package java.util; /** * An object which iterates over a collection. An Iterator is used to return * the items once only, in sequence, by successive calls to the next method. * It is also possible to remove elements from the underlying collection by * using the optional remove method. Iterator is intended as a replacement * for the Enumeration interface of previous versions of Java, which did not * have the remove method and had less conveniently named methods. * * @author Original author unknown * @author Eric Blake (ebb9@email.byu.edu) * @see Collection * @see ListIterator * @see Enumeration * @since 1.2 * @status updated to 1.4 */ public interface Iterator { /** * Tests whether there are elements remaining in the collection. In other * words, calling <code>next()</code> will not throw an exception. * * @return true if there is at least one more element in the collection */ boolean hasNext(); /** * Obtain the next element in the collection. * * @return the next element in the collection * @throws NoSuchElementException if there are no more elements */ Object next(); /** * Remove from the underlying collection the last element returned by next * (optional operation). This method can be called only once after each * call to <code>next()</code>. It does not affect what will be returned * by subsequent calls to next. * * @throws IllegalStateException if next has not yet been called or remove * has already been called since the last call to next. * @throws UnsupportedOperationException if this Iterator does not support * the remove operation. */ void remove(); }