/*
* @(#)CharSequence.java 1.9 06/10/10
*
* Copyright 1990-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 only, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License version 2 for more details (a copy is
* included at /legal/license.txt).
*
* You should have received a copy of the GNU General Public License
* version 2 along with this work; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*/
package java.lang;
/**
* A <tt>CharSequence</tt> is a readable sequence of characters. This
* interface provides uniform, read-only access to many different kinds of
* character sequences.
*
* <p> This interface does not refine the general contracts of the {@link
* java.lang.Object#equals(java.lang.Object) equals} and {@link
* java.lang.Object#hashCode() hashCode} methods. The result of comparing two
* objects that implement <tt>CharSequence</tt> is therefore, in general,
* undefined. Each object may be implemented by a different class, and there
* is no guarantee that each class will be capable of testing its instances
* for equality with those of the other. It is therefore inappropriate to use
* arbitrary <tt>CharSequence</tt> instances as elements in a set or as keys in
* a map. </p>
*
* @author Mike McCloskey
* @version 1.9 06/10/10
* @since 1.4
* @spec JSR-51
*/
public interface CharSequence {
/**
* Returns the length of this character sequence. The length is the number
* of 16-bit Unicode characters in the sequence. </p>
*
* @return the number of characters in this sequence
*/
int length();
/**
* Returns the character at the specified index. An index ranges from zero
* to <tt>length() - 1</tt>. The first character of the sequence is at
* index zero, the next at index one, and so on, as for array
* indexing. </p>
*
* @param index the index of the character to be returned
*
* @return the specified character
*
* @throws IndexOutOfBoundsException
* if the <tt>index</tt> argument is negative or not less than
* <tt>length()</tt>
*/
char charAt(int index);
/**
* Returns a new character sequence that is a subsequence of this sequence.
* The subsequence starts with the character at the specified index and
* ends with the character at index <tt>end - 1</tt>. The length of the
* returned sequence is <tt>end - start</tt>, so if <tt>start == end</tt>
* then an empty sequence is returned. </p>
*
* @param start the start index, inclusive
* @param end the end index, exclusive
*
* @return the specified subsequence
*
* @throws IndexOutOfBoundsException
* if <tt>start</tt> or <tt>end</tt> are negative,
* if <tt>end</tt> is greater than <tt>length()</tt>,
* or if <tt>start</tt> is greater than <tt>end</tt>
*/
CharSequence subSequence(int start, int end);
/**
* Returns a string containing the characters in this sequence in the same
* order as this sequence. The length of the string will be the length of
* this sequence. </p>
*
* @return a string consisting of exactly this sequence of characters
*/
public String toString();
}