emul/compact/src/main/java/java/util/RandomAccess.java
author Jaroslav Tulach <jaroslav.tulach@apidesign.org>
Wed, 23 Jan 2013 22:32:27 +0100
branchjdk7-b147
changeset 557 5be31d9fa455
permissions -rw-r--r--
Basic classes needed to support ServiceLoader
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/*
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 * Copyright (c) 2000, 2006, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.  Oracle designates this
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 * particular file as subject to the "Classpath" exception as provided
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 * by Oracle in the LICENSE file that accompanied this code.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 */
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package java.util;
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/**
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 * Marker interface used by <tt>List</tt> implementations to indicate that
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 * they support fast (generally constant time) random access.  The primary
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 * purpose of this interface is to allow generic algorithms to alter their
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 * behavior to provide good performance when applied to either random or
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 * sequential access lists.
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 *
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 * <p>The best algorithms for manipulating random access lists (such as
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 * <tt>ArrayList</tt>) can produce quadratic behavior when applied to
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 * sequential access lists (such as <tt>LinkedList</tt>).  Generic list
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 * algorithms are encouraged to check whether the given list is an
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 * <tt>instanceof</tt> this interface before applying an algorithm that would
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 * provide poor performance if it were applied to a sequential access list,
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 * and to alter their behavior if necessary to guarantee acceptable
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 * performance.
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 *
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 * <p>It is recognized that the distinction between random and sequential
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 * access is often fuzzy.  For example, some <tt>List</tt> implementations
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 * provide asymptotically linear access times if they get huge, but constant
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 * access times in practice.  Such a <tt>List</tt> implementation
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 * should generally implement this interface.  As a rule of thumb, a
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 * <tt>List</tt> implementation should implement this interface if,
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 * for typical instances of the class, this loop:
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 * <pre>
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 *     for (int i=0, n=list.size(); i &lt; n; i++)
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 *         list.get(i);
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 * </pre>
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 * runs faster than this loop:
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 * <pre>
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 *     for (Iterator i=list.iterator(); i.hasNext(); )
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 *         i.next();
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 * </pre>
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 *
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 * <p>This interface is a member of the
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 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
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 * Java Collections Framework</a>.
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 *
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 * @since 1.4
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 */
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public interface RandomAccess {
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}