Java tutorial
/* * Copyright (c) 2000, 2018, 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; /** * Marker interface used by {@code List} implementations to indicate that * they support fast (generally constant time) random access. The primary * purpose of this interface is to allow generic algorithms to alter their * behavior to provide good performance when applied to either random or * sequential access lists. * * <p>The best algorithms for manipulating random access lists (such as * {@code ArrayList}) can produce quadratic behavior when applied to * sequential access lists (such as {@code LinkedList}). Generic list * algorithms are encouraged to check whether the given list is an * {@code instanceof} this interface before applying an algorithm that would * provide poor performance if it were applied to a sequential access list, * and to alter their behavior if necessary to guarantee acceptable * performance. * * <p>It is recognized that the distinction between random and sequential * access is often fuzzy. For example, some {@code List} implementations * provide asymptotically linear access times if they get huge, but constant * access times in practice. Such a {@code List} implementation * should generally implement this interface. As a rule of thumb, a * {@code List} implementation should implement this interface if, * for typical instances of the class, this loop: * <pre> * for (int i=0, n=list.size(); i < n; i++) * list.get(i); * </pre> * runs faster than this loop: * <pre> * for (Iterator i=list.iterator(); i.hasNext(); ) * i.next(); * </pre> * * <p>This interface is a member of the * <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework"> * Java Collections Framework</a>. * * @since 1.4 */ public interface RandomAccess { }