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1   /*
2    * Copyright (c) 2003, 2004, Oracle and/or its affiliates. All rights reserved.
3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4    *
5    * This code is free software; you can redistribute it and/or modify it
6    * under the terms of the GNU General Public License version 2 only, as
7    * published by the Free Software Foundation.  Oracle designates this
8    * particular file as subject to the "Classpath" exception as provided
9    * by Oracle in the LICENSE file that accompanied this code.
10   *
11   * This code is distributed in the hope that it will be useful, but WITHOUT
12   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14   * version 2 for more details (a copy is included in the LICENSE file that
15   * accompanied this code).
16   *
17   * You should have received a copy of the GNU General Public License version
18   * 2 along with this work; if not, write to the Free Software Foundation,
19   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20   *
21   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22   * or visit www.oracle.com if you need additional information or have any
23   * questions.
24   */
25  
26  package java.lang;
27  
28  import java.io.IOException;
29  
30  /**
31   * An object to which <tt>char</tt> sequences and values can be appended.  The
32   * <tt>Appendable</tt> interface must be implemented by any class whose
33   * instances are intended to receive formatted output from a {@link
34   * java.util.Formatter}.
35   *
36   * <p> The characters to be appended should be valid Unicode characters as
37   * described in <a href="Character.html#unicode">Unicode Character
38   * Representation</a>.  Note that supplementary characters may be composed of
39   * multiple 16-bit <tt>char</tt> values.
40   *
41   * <p> Appendables are not necessarily safe for multithreaded access.  Thread
42   * safety is the responsibility of classes that extend and implement this
43   * interface.
44   *
45   * <p> Since this interface may be implemented by existing classes
46   * with different styles of error handling there is no guarantee that
47   * errors will be propagated to the invoker.
48   *
49   * @since 1.5
50   */
51  public interface Appendable {
52  
53      /**
54       * Appends the specified character sequence to this <tt>Appendable</tt>.
55       *
56       * <p> Depending on which class implements the character sequence
57       * <tt>csq</tt>, the entire sequence may not be appended.  For
58       * instance, if <tt>csq</tt> is a {@link java.nio.CharBuffer} then
59       * the subsequence to append is defined by the buffer's position and limit.
60       *
61       * @param  csq
62       *         The character sequence to append.  If <tt>csq</tt> is
63       *         <tt>null</tt>, then the four characters <tt>"null"</tt> are
64       *         appended to this Appendable.
65       *
66       * @return  A reference to this <tt>Appendable</tt>
67       *
68       * @throws  IOException
69       *          If an I/O error occurs
70       */
71      Appendable append(CharSequence csq) throws IOException;
72  
73      /**
74       * Appends a subsequence of the specified character sequence to this
75       * <tt>Appendable</tt>.
76       *
77       * <p> An invocation of this method of the form <tt>out.append(csq, start,
78       * end)</tt> when <tt>csq</tt> is not <tt>null</tt>, behaves in
79       * exactly the same way as the invocation
80       *
81       * <pre>
82       *     out.append(csq.subSequence(start, end)) </pre>
83       *
84       * @param  csq
85       *         The character sequence from which a subsequence will be
86       *         appended.  If <tt>csq</tt> is <tt>null</tt>, then characters
87       *         will be appended as if <tt>csq</tt> contained the four
88       *         characters <tt>"null"</tt>.
89       *
90       * @param  start
91       *         The index of the first character in the subsequence
92       *
93       * @param  end
94       *         The index of the character following the last character in the
95       *         subsequence
96       *
97       * @return  A reference to this <tt>Appendable</tt>
98       *
99       * @throws  IndexOutOfBoundsException
100      *          If <tt>start</tt> or <tt>end</tt> are negative, <tt>start</tt>
101      *          is greater than <tt>end</tt>, or <tt>end</tt> is greater than
102      *          <tt>csq.length()</tt>
103      *
104      * @throws  IOException
105      *          If an I/O error occurs
106      */
107     Appendable append(CharSequence csq, int start, int end) throws IOException;
108 
109     /**
110      * Appends the specified character to this <tt>Appendable</tt>.
111      *
112      * @param  c
113      *         The character to append
114      *
115      * @return  A reference to this <tt>Appendable</tt>
116      *
117      * @throws  IOException
118      *          If an I/O error occurs
119      */
120     Appendable append(char c) throws IOException;
121 }