1. /*

  2.  * @(#)RandomAccess.java	1.5 03/01/23

  3.  *

  4.  * Copyright 2003 Sun Microsystems, Inc. All rights reserved.

  5.  * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.

  6.  */

  7. 

  8. package java.util;

  9. 

  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}/../guide/collections/index.html">

  45.  * Java Collections Framework</a>.

  46.  *

  47.  */

  48. public interface RandomAccess {

  49. }