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
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24 */
25
26package java.lang;
27
28import java.io.IOException;
29
30/**
31 * An object to which {@code char} sequences and values can be appended.  The
32 * {@code Appendable} 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 {@code char} 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 */
51public interface Appendable {
52
53    /**
54     * Appends the specified character sequence to this {@code Appendable}.
55     *
56     * <p> Depending on which class implements the character sequence
57     * {@code csq}, the entire sequence may not be appended.  For
58     * instance, if {@code csq} 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 {@code csq} is
63     *         {@code null}, then the four characters {@code "null"} are
64     *         appended to this Appendable.
65     *
66     * @return  A reference to this {@code Appendable}
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     * {@code Appendable}.
76     *
77     * <p> An invocation of this method of the form {@code out.append(csq, start, end)}
78     * when {@code csq} is not {@code null}, 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 {@code csq} is {@code null}, then characters
87     *         will be appended as if {@code csq} contained the four
88     *         characters {@code "null"}.
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 {@code Appendable}
98     *
99     * @throws  IndexOutOfBoundsException
100     *          If {@code start} or {@code end} are negative, {@code start}
101     *          is greater than {@code end}, or {@code end} is greater than
102     *          {@code csq.length()}
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 {@code Appendable}.
111     *
112     * @param  c
113     *         The character to append
114     *
115     * @return  A reference to this {@code Appendable}
116     *
117     * @throws  IOException
118     *          If an I/O error occurs
119     */
120    Appendable append(char c) throws IOException;
121}
122