1/*
2 * Copyright (c) 1996, 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
26package java.io;
27
28
29/**
30 * A character stream that collects its output in a string buffer, which can
31 * then be used to construct a string.
32 * <p>
33 * Closing a <tt>StringWriter</tt> has no effect. The methods in this class
34 * can be called after the stream has been closed without generating an
35 * <tt>IOException</tt>.
36 *
37 * @author      Mark Reinhold
38 * @since       JDK1.1
39 */
40
41public class StringWriter extends Writer {
42
43    private StringBuffer buf;
44
45    /**
46     * Create a new string writer using the default initial string-buffer
47     * size.
48     */
49    public StringWriter() {
50        buf = new StringBuffer();
51        lock = buf;
52    }
53
54    /**
55     * Create a new string writer using the specified initial string-buffer
56     * size.
57     *
58     * @param initialSize
59     *        The number of <tt>char</tt> values that will fit into this buffer
60     *        before it is automatically expanded
61     *
62     * @throws IllegalArgumentException
63     *         If <tt>initialSize</tt> is negative
64     */
65    public StringWriter(int initialSize) {
66        if (initialSize < 0) {
67            throw new IllegalArgumentException("Negative buffer size");
68        }
69        buf = new StringBuffer(initialSize);
70        lock = buf;
71    }
72
73    /**
74     * Write a single character.
75     */
76    public void write(int c) {
77        buf.append((char) c);
78    }
79
80    /**
81     * Write a portion of an array of characters.
82     *
83     * @param  cbuf  Array of characters
84     * @param  off   Offset from which to start writing characters
85     * @param  len   Number of characters to write
86     */
87    public void write(char cbuf[], int off, int len) {
88        if ((off < 0) || (off > cbuf.length) || (len < 0) ||
89            ((off + len) > cbuf.length) || ((off + len) < 0)) {
90            throw new IndexOutOfBoundsException();
91        } else if (len == 0) {
92            return;
93        }
94        buf.append(cbuf, off, len);
95    }
96
97    /**
98     * Write a string.
99     */
100    public void write(String str) {
101        buf.append(str);
102    }
103
104    /**
105     * Write a portion of a string.
106     *
107     * @param  str  String to be written
108     * @param  off  Offset from which to start writing characters
109     * @param  len  Number of characters to write
110     */
111    public void write(String str, int off, int len)  {
112        buf.append(str.substring(off, off + len));
113    }
114
115    /**
116     * Appends the specified character sequence to this writer.
117     *
118     * <p> An invocation of this method of the form <tt>out.append(csq)</tt>
119     * behaves in exactly the same way as the invocation
120     *
121     * <pre>
122     *     out.write(csq.toString()) </pre>
123     *
124     * <p> Depending on the specification of <tt>toString</tt> for the
125     * character sequence <tt>csq</tt>, the entire sequence may not be
126     * appended. For instance, invoking the <tt>toString</tt> method of a
127     * character buffer will return a subsequence whose content depends upon
128     * the buffer's position and limit.
129     *
130     * @param  csq
131     *         The character sequence to append.  If <tt>csq</tt> is
132     *         <tt>null</tt>, then the four characters <tt>"null"</tt> are
133     *         appended to this writer.
134     *
135     * @return  This writer
136     *
137     * @since  1.5
138     */
139    public StringWriter append(CharSequence csq) {
140        if (csq == null)
141            write("null");
142        else
143            write(csq.toString());
144        return this;
145    }
146
147    /**
148     * Appends a subsequence of the specified character sequence to this writer.
149     *
150     * <p> An invocation of this method of the form <tt>out.append(csq, start,
151     * end)</tt> when <tt>csq</tt> is not <tt>null</tt>, behaves in
152     * exactly the same way as the invocation
153     *
154     * <pre>
155     *     out.write(csq.subSequence(start, end).toString()) </pre>
156     *
157     * @param  csq
158     *         The character sequence from which a subsequence will be
159     *         appended.  If <tt>csq</tt> is <tt>null</tt>, then characters
160     *         will be appended as if <tt>csq</tt> contained the four
161     *         characters <tt>"null"</tt>.
162     *
163     * @param  start
164     *         The index of the first character in the subsequence
165     *
166     * @param  end
167     *         The index of the character following the last character in the
168     *         subsequence
169     *
170     * @return  This writer
171     *
172     * @throws  IndexOutOfBoundsException
173     *          If <tt>start</tt> or <tt>end</tt> are negative, <tt>start</tt>
174     *          is greater than <tt>end</tt>, or <tt>end</tt> is greater than
175     *          <tt>csq.length()</tt>
176     *
177     * @since  1.5
178     */
179    public StringWriter append(CharSequence csq, int start, int end) {
180        CharSequence cs = (csq == null ? "null" : csq);
181        write(cs.subSequence(start, end).toString());
182        return this;
183    }
184
185    /**
186     * Appends the specified character to this writer.
187     *
188     * <p> An invocation of this method of the form <tt>out.append(c)</tt>
189     * behaves in exactly the same way as the invocation
190     *
191     * <pre>
192     *     out.write(c) </pre>
193     *
194     * @param  c
195     *         The 16-bit character to append
196     *
197     * @return  This writer
198     *
199     * @since 1.5
200     */
201    public StringWriter append(char c) {
202        write(c);
203        return this;
204    }
205
206    /**
207     * Return the buffer's current value as a string.
208     */
209    public String toString() {
210        return buf.toString();
211    }
212
213    /**
214     * Return the string buffer itself.
215     *
216     * @return StringBuffer holding the current buffer value.
217     */
218    public StringBuffer getBuffer() {
219        return buf;
220    }
221
222    /**
223     * Flush the stream.
224     */
225    public void flush() {
226    }
227
228    /**
229     * Closing a <tt>StringWriter</tt> has no effect. The methods in this
230     * class can be called after the stream has been closed without generating
231     * an <tt>IOException</tt>.
232     */
233    public void close() throws IOException {
234    }
235
236}
237