jaroslav@557: /*
jaroslav@557:  * Copyright (c) 2000, 2006, Oracle and/or its affiliates. All rights reserved.
jaroslav@557:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jaroslav@557:  *
jaroslav@557:  * This code is free software; you can redistribute it and/or modify it
jaroslav@557:  * under the terms of the GNU General Public License version 2 only, as
jaroslav@557:  * published by the Free Software Foundation.  Oracle designates this
jaroslav@557:  * particular file as subject to the "Classpath" exception as provided
jaroslav@557:  * by Oracle in the LICENSE file that accompanied this code.
jaroslav@557:  *
jaroslav@557:  * This code is distributed in the hope that it will be useful, but WITHOUT
jaroslav@557:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jaroslav@557:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jaroslav@557:  * version 2 for more details (a copy is included in the LICENSE file that
jaroslav@557:  * accompanied this code).
jaroslav@557:  *
jaroslav@557:  * You should have received a copy of the GNU General Public License version
jaroslav@557:  * 2 along with this work; if not, write to the Free Software Foundation,
jaroslav@557:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jaroslav@557:  *
jaroslav@557:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jaroslav@557:  * or visit www.oracle.com if you need additional information or have any
jaroslav@557:  * questions.
jaroslav@557:  */
jaroslav@557: 
jaroslav@557: package java.util;
jaroslav@557: 
jaroslav@557: /**
jaroslav@557:  * Marker interface used by <tt>List</tt> implementations to indicate that
jaroslav@557:  * they support fast (generally constant time) random access.  The primary
jaroslav@557:  * purpose of this interface is to allow generic algorithms to alter their
jaroslav@557:  * behavior to provide good performance when applied to either random or
jaroslav@557:  * sequential access lists.
jaroslav@557:  *
jaroslav@557:  * <p>The best algorithms for manipulating random access lists (such as
jaroslav@557:  * <tt>ArrayList</tt>) can produce quadratic behavior when applied to
jaroslav@557:  * sequential access lists (such as <tt>LinkedList</tt>).  Generic list
jaroslav@557:  * algorithms are encouraged to check whether the given list is an
jaroslav@557:  * <tt>instanceof</tt> this interface before applying an algorithm that would
jaroslav@557:  * provide poor performance if it were applied to a sequential access list,
jaroslav@557:  * and to alter their behavior if necessary to guarantee acceptable
jaroslav@557:  * performance.
jaroslav@557:  *
jaroslav@557:  * <p>It is recognized that the distinction between random and sequential
jaroslav@557:  * access is often fuzzy.  For example, some <tt>List</tt> implementations
jaroslav@557:  * provide asymptotically linear access times if they get huge, but constant
jaroslav@557:  * access times in practice.  Such a <tt>List</tt> implementation
jaroslav@557:  * should generally implement this interface.  As a rule of thumb, a
jaroslav@557:  * <tt>List</tt> implementation should implement this interface if,
jaroslav@557:  * for typical instances of the class, this loop:
jaroslav@557:  * <pre>
jaroslav@557:  *     for (int i=0, n=list.size(); i &lt; n; i++)
jaroslav@557:  *         list.get(i);
jaroslav@557:  * </pre>
jaroslav@557:  * runs faster than this loop:
jaroslav@557:  * <pre>
jaroslav@557:  *     for (Iterator i=list.iterator(); i.hasNext(); )
jaroslav@557:  *         i.next();
jaroslav@557:  * </pre>
jaroslav@557:  *
jaroslav@557:  * <p>This interface is a member of the
jaroslav@557:  * <a href="{@docRoot}/../technotes/guides/collections/index.html">
jaroslav@557:  * Java Collections Framework</a>.
jaroslav@557:  *
jaroslav@557:  * @since 1.4
jaroslav@557:  */
jaroslav@557: public interface RandomAccess {
jaroslav@557: }