- 01
/* - 02
* @(#)RandomAccess.java 1.9 06/04/21 - 03 *
- 04 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
- 05 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
- 06
*/ - 07
- 08package java.util;
- 09
- 10/**
- 11 * Marker interface used by <tt>List</tt> implementations to indicate that
- 12 * they support fast (generally constant time) random access. The primary
- 13 * purpose of this interface is to allow generic algorithms to alter their
- 14 * behavior to provide good performance when applied to either random or
- 15 * sequential access lists.
- 16 *
- 17 * <p>The best algorithms for manipulating random access lists (such as
- 18 * <tt>ArrayList</tt>) can produce quadratic behavior when applied to
- 19 * sequential access lists (such as <tt>LinkedList</tt>). Generic list
- 20 * algorithms are encouraged to check whether the given list is an
- 21 * <tt>instanceof</tt> this interface before applying an algorithm that would
- 22 * provide poor performance if it were applied to a sequential access list,
- 23 * and to alter their behavior if necessary to guarantee acceptable
- 24 * performance.
- 25 *
- 26 * <p>It is recognized that the distinction between random and sequential
- 27 * access is often fuzzy. For example, some <tt>List</tt> implementations
- 28 * provide asymptotically linear access times if they get huge, but constant
- 29 * access times in practice. Such a <tt>List</tt> implementation
- 30 * should generally implement this interface. As a rule of thumb, a
- 31 * <tt>List</tt> implementation should implement this interface if,
- 32 * for typical instances of the class, this loop:
- 33 * <pre>
- 34 * for (int i=0, n=list.size(); i < n; i++)
- 35 * list.get(i);
- 36 * </pre>
- 37 * runs faster than this loop:
- 38 * <pre>
- 39 * for (Iterator i=list.iterator(); i.hasNext(); )
- 40 * i.next();
- 41 * </pre>
- 42 *
- 43 * <p>This interface is a member of the
- 44 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
- 45 * Java Collections Framework</a>.
- 46 *
- 47 * @since 1.4
- 48 */
- 49public interface RandomAccess {
- 50}
