gomp-20050608-branch/libjava/classpath/java/lang/CharSequence.java

   1 /* CharSequence.java -- Anything that has an indexed sequence of chars
   2    Copyright (C) 2001, 2002 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.lang;
  40
  41 /**
  42  * General functions on a sequence of chars. This interface is implemented
  43  * by <code>String</code>, <code>StringBuffer</code> and
  44  * <code>CharBuffer</code> to give a uniform way to get chars at a certain
  45  * index, the number of characters in the sequence and a subrange of the
  46  * chars. Indexes start at 0 and the last index is <code>length()-1</code>.
  47  *
  48  * <p>Even when classes implement this interface they are not always
  49  * exchangeble because they might implement their compare, equals or hash
  50  * function differently. This means that in general one should not use a
  51  * <code>CharSequence</code> as keys in collections since two sequences
  52  * with the same chars at the same indexes with the same length might not
  53  * have the same hash code, be equal or be comparable since the are
  54  * represented by different classes.
  55  *
  56  * @author Mark Wielaard (mark@klomp.org)
  57  * @since 1.4
  58  * @status updated to 1.4
  59  */
  60 public interface CharSequence
  61 {
  62   /**
  63    * Returns the character at the given index.
  64    *
  65    * @param i the index to retrieve from
  66    * @return the character at that location
  67    * @throws IndexOutOfBoundsException if i &lt; 0 || i &gt;= length() - 1
  68    */
  69   char charAt(int i);
  70
  71   /**
  72    * Returns the length of the sequence. This is the number of 16-bit
  73    * characters in the sequence, which may differ from the length of the
  74    * underlying encoding.
  75    *
  76    * @return the sequence length
  77    */
  78   int length();
  79
  80   /**
  81    * Returns a new <code>CharSequence</code> of the indicated range.
  82    *
  83    * @param begin the start index (inclusive)
  84    * @param end the end index (exclusive)
  85    * @return a subsequence of this
  86    * @throws IndexOutOfBoundsException if begin &gt; end || begin &lt; 0 ||
  87    *         end &gt; length()
  88    */
  89   CharSequence subSequence(int begin, int end);
  90
  91   /**
  92    * Returns the complete <code>CharSequence</code> as a <code>String</code>.
  93    * Classes that implement this interface should return a <code>String</code>
  94    * which contains only the characters in the sequence in the correct order.
  95    *
  96    * @return the character sequence as a String
  97    */
  98   String toString();
  99 }