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., 59 Temple Place, Suite 330, Boston, MA 19 02111-1307 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 < 0 || i >= length() - 1 68 */ charAt(int i)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 */ length()78 int length(); 79 80 /** 81 * Returns a new <code>CharSequence</char> 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 > end || begin < 0 || 87 * end > length() 88 */ subSequence(int begin, int end)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 */ toString()98 String toString(); 99 } 100