1 /*
2 * Copyright (c) 2003, 2008, 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
29 /**
30 * A mutable sequence of characters. This class provides an API compatible
31 * with <code>StringBuffer</code>, but with no guarantee of synchronization.
32 * This class is designed for use as a drop-in replacement for
33 * <code>StringBuffer</code> in places where the string buffer was being
34 * used by a single thread (as is generally the case). Where possible,
35 * it is recommended that this class be used in preference to
36 * <code>StringBuffer</code> as it will be faster under most implementations.
37 *
38 * <p>The principal operations on a <code>StringBuilder</code> are the
39 * <code>append</code> and <code>insert</code> methods, which are
40 * overloaded so as to accept data of any type. Each effectively
41 * converts a given datum to a string and then appends or inserts the
42 * characters of that string to the string builder. The
43 * <code>append</code> method always adds these characters at the end
44 * of the builder; the <code>insert</code> method adds the characters at
45 * a specified point.
46 * <p>
47 * For example, if <code>z</code> refers to a string builder object
48 * whose current contents are "<code>start</code>", then
49 * the method call <code>z.append("le")</code> would cause the string
50 * builder to contain "<code>startle</code>", whereas
51 * <code>z.insert(4, "le")</code> would alter the string builder to
52 * contain "<code>starlet</code>".
53 * <p>
54 * In general, if sb refers to an instance of a <code>StringBuilder</code>,
55 * then <code>sb.append(x)</code> has the same effect as
56 * <code>sb.insert(sb.length(), x)</code>.
57 *
58 * Every string builder has a capacity. As long as the length of the
59 * character sequence contained in the string builder does not exceed
60 * the capacity, it is not necessary to allocate a new internal
61 * buffer. If the internal buffer overflows, it is automatically made larger.
62 *
63 * <p>Instances of <code>StringBuilder</code> are not safe for
64 * use by multiple threads. If such synchronization is required then it is
65 * recommended that {@link java.lang.StringBuffer} be used.
66 *
67 * @author Michael McCloskey
68 * @see java.lang.StringBuffer
69 * @see java.lang.String
70 * @since 1.5
71 */
72 public final class StringBuilder
73 extends AbstractStringBuilder
74 implements java.io.Serializable, CharSequence
75 {
76
77 /** use serialVersionUID for interoperability */
78 static final long serialVersionUID = 4383685877147921099L;
79
80 /**
81 * Constructs a string builder with no characters in it and an
82 * initial capacity of 16 characters.
83 */
84 public StringBuilder() {
85 super(16);
86 }
87
88 /**
89 * Constructs a string builder with no characters in it and an
90 * initial capacity specified by the <code>capacity</code> argument.
91 *
92 * @param capacity the initial capacity.
93 * @throws NegativeArraySizeException if the <code>capacity</code>
94 * argument is less than <code>0</code>.
95 */
96 public StringBuilder(int capacity) {
97 super(capacity);
98 }
99
100 /**
101 * Constructs a string builder initialized to the contents of the
102 * specified string. The initial capacity of the string builder is
103 * <code>16</code> plus the length of the string argument.
104 *
105 * @param str the initial contents of the buffer.
106 * @throws NullPointerException if <code>str</code> is <code>null</code>
107 */
108 public StringBuilder(String str) {
109 super(str.length() + 16);
110 append(str);
111 }
112
113 /**
114 * Constructs a string builder that contains the same characters
115 * as the specified <code>CharSequence</code>. The initial capacity of
116 * the string builder is <code>16</code> plus the length of the
117 * <code>CharSequence</code> argument.
118 *
119 * @param seq the sequence to copy.
120 * @throws NullPointerException if <code>seq</code> is <code>null</code>
121 */
122 public StringBuilder(CharSequence seq) {
123 this(seq.length() + 16);
124 append(seq);
125 }
126
127 public StringBuilder append(Object obj) {
128 return append(String.valueOf(obj));
129 }
130
131 public StringBuilder append(String str) {
132 super.append(str);
133 return this;
134 }
135
136 // Appends the specified string builder to this sequence.
137 private StringBuilder append(StringBuilder sb) {
138 if (sb == null)
139 return append("null");
140 int len = sb.length();
141 int newcount = count + len;
142 if (newcount > value.length)
143 expandCapacity(newcount);
144 sb.getChars(0, len, value, count);
145 count = newcount;
146 return this;
147 }
148
149 /**
150 * Appends the specified <tt>StringBuffer</tt> to this sequence.
151 * <p>
152 * The characters of the <tt>StringBuffer</tt> argument are appended,
153 * in order, to this sequence, increasing the
154 * length of this sequence by the length of the argument.
155 * If <tt>sb</tt> is <tt>null</tt>, then the four characters
156 * <tt>"null"</tt> are appended to this sequence.
157 * <p>
158 * Let <i>n</i> be the length of this character sequence just prior to
159 * execution of the <tt>append</tt> method. Then the character at index
160 * <i>k</i> in the new character sequence is equal to the character at
161 * index <i>k</i> in the old character sequence, if <i>k</i> is less than
162 * <i>n</i>; otherwise, it is equal to the character at index <i>k-n</i>
163 * in the argument <code>sb</code>.
164 *
165 * @param sb the <tt>StringBuffer</tt> to append.
166 * @return a reference to this object.
167 */
168 public StringBuilder append(StringBuffer sb) {
169 super.append(sb);
170 return this;
171 }
172
173 /**
174 */
175 public StringBuilder append(CharSequence s) {
176 if (s == null)
177 s = "null";
178 if (s instanceof String)
179 return this.append((String)s);
180 if (s instanceof StringBuffer)
181 return this.append((StringBuffer)s);
182 if (s instanceof StringBuilder)
183 return this.append((StringBuilder)s);
184 return this.append(s, 0, s.length());
185 }
186
187 /**
188 * @throws IllegalArgumentException if n < 0 {@inheritDoc}
189 * @since 1.8
190 */
191 public StringBuilder append(int n, CharSequence cs) {
192 super.append(n, cs);
193 return this;
194 }
195
196 /**
197 * @throws IndexOutOfBoundsException {@inheritDoc}
198 */
199 public StringBuilder append(CharSequence s, int start, int end) {
200 super.append(s, start, end);
201 return this;
202 }
203
204 public StringBuilder append(char[] str) {
205 super.append(str);
206 return this;
207 }
208
209 /**
210 * @throws IndexOutOfBoundsException {@inheritDoc}
211 */
212 public StringBuilder append(char[] str, int offset, int len) {
213 super.append(str, offset, len);
214 return this;
215 }
216
217 public StringBuilder append(boolean b) {
218 super.append(b);
219 return this;
220 }
221
222 public StringBuilder append(char c) {
223 super.append(c);
224 return this;
225 }
226
227 public StringBuilder append(int i) {
228 super.append(i);
229 return this;
230 }
231
232 public StringBuilder append(long lng) {
233 super.append(lng);
234 return this;
235 }
236
237 public StringBuilder append(float f) {
238 super.append(f);
239 return this;
240 }
241
242 public StringBuilder append(double d) {
243 super.append(d);
244 return this;
245 }
246
247 /**
248 * @since 1.5
249 */
250 public StringBuilder appendCodePoint(int codePoint) {
251 super.appendCodePoint(codePoint);
252 return this;
253 }
254
255 /**
256 * @throws StringIndexOutOfBoundsException {@inheritDoc}
257 */
258 public StringBuilder delete(int start, int end) {
259 super.delete(start, end);
260 return this;
261 }
262
263 /**
264 * @throws StringIndexOutOfBoundsException {@inheritDoc}
265 */
266 public StringBuilder deleteCharAt(int index) {
267 super.deleteCharAt(index);
268 return this;
269 }
270
271 /**
272 * @throws StringIndexOutOfBoundsException {@inheritDoc}
273 */
274 public StringBuilder replace(int start, int end, String str) {
275 super.replace(start, end, str);
276 return this;
277 }
278
279 /**
280 * @throws StringIndexOutOfBoundsException {@inheritDoc}
281 */
282 public StringBuilder insert(int index, char[] str, int offset,
283 int len)
284 {
285 super.insert(index, str, offset, len);
286 return this;
287 }
288
289 /**
290 * @throws StringIndexOutOfBoundsException {@inheritDoc}
291 */
292 public StringBuilder insert(int offset, Object obj) {
293 return insert(offset, String.valueOf(obj));
294 }
295
296 /**
297 * @throws StringIndexOutOfBoundsException {@inheritDoc}
298 */
299 public StringBuilder insert(int offset, String str) {
300 super.insert(offset, str);
301 return this;
302 }
303
304 /**
305 * @throws StringIndexOutOfBoundsException {@inheritDoc}
306 */
307 public StringBuilder insert(int offset, char[] str) {
308 super.insert(offset, str);
309 return this;
310 }
311
312 /**
313 * @throws IndexOutOfBoundsException {@inheritDoc}
314 */
315 public StringBuilder insert(int dstOffset, CharSequence s) {
316 if (s == null)
317 s = "null";
318 if (s instanceof String)
319 return this.insert(dstOffset, (String)s);
320 return this.insert(dstOffset, s, 0, s.length());
321 }
322
323 /**
324 * @throws IndexOutOfBoundsException {@inheritDoc}
325 */
326 public StringBuilder insert(int dstOffset, CharSequence s,
327 int start, int end)
328 {
329 super.insert(dstOffset, s, start, end);
330 return this;
331 }
332
333 /**
334 * @throws StringIndexOutOfBoundsException {@inheritDoc}
335 */
336 public StringBuilder insert(int offset, boolean b) {
337 super.insert(offset, b);
338 return this;
339 }
340
341 /**
342 * @throws IndexOutOfBoundsException {@inheritDoc}
343 */
344 public StringBuilder insert(int offset, char c) {
345 super.insert(offset, c);
346 return this;
347 }
348
349 /**
350 * @throws StringIndexOutOfBoundsException {@inheritDoc}
351 */
352 public StringBuilder insert(int offset, int i) {
353 return insert(offset, String.valueOf(i));
354 }
355
356 /**
357 * @throws StringIndexOutOfBoundsException {@inheritDoc}
358 */
359 public StringBuilder insert(int offset, long l) {
360 return insert(offset, String.valueOf(l));
361 }
362
363 /**
364 * @throws StringIndexOutOfBoundsException {@inheritDoc}
365 */
366 public StringBuilder insert(int offset, float f) {
367 return insert(offset, String.valueOf(f));
368 }
369
370 /**
371 * @throws StringIndexOutOfBoundsException {@inheritDoc}
372 */
373 public StringBuilder insert(int offset, double d) {
374 return insert(offset, String.valueOf(d));
375 }
376
377 /**
378 * @throws NullPointerException {@inheritDoc}
379 */
380 public int indexOf(String str) {
381 return indexOf(str, 0);
382 }
383
384 /**
385 * @throws NullPointerException {@inheritDoc}
386 */
387 public int indexOf(String str, int fromIndex) {
388 return String.indexOf(value, 0, count,
389 str.toCharArray(), 0, str.length(), fromIndex);
390 }
391
392 /**
393 * @throws NullPointerException {@inheritDoc}
394 */
395 public int lastIndexOf(String str) {
396 return lastIndexOf(str, count);
397 }
398
399 /**
400 * @throws NullPointerException {@inheritDoc}
401 */
402 public int lastIndexOf(String str, int fromIndex) {
403 return String.lastIndexOf(value, 0, count,
404 str.toCharArray(), 0, str.length(), fromIndex);
405 }
406
407 public StringBuilder reverse() {
408 super.reverse();
409 return this;
410 }
411
412 public String toString() {
413 // Create a copy, don't share the array
414 return new String(value, 0, count);
415 }
416
417 /**
418 * Save the state of the <tt>StringBuilder</tt> instance to a stream
419 * (that is, serialize it).
420 *
421 * @serialData the number of characters currently stored in the string
422 * builder (<tt>int</tt>), followed by the characters in the
423 * string builder (<tt>char[]</tt>). The length of the
424 * <tt>char</tt> array may be greater than the number of
425 * characters currently stored in the string builder, in which
426 * case extra characters are ignored.
427 */
428 private void writeObject(java.io.ObjectOutputStream s)
429 throws java.io.IOException {
430 s.defaultWriteObject();
431 s.writeInt(count);
432 s.writeObject(value);
433 }
434
435 /**
436 * readObject is called to restore the state of the StringBuffer from
437 * a stream.
438 */
439 private void readObject(java.io.ObjectInputStream s)
440 throws java.io.IOException, ClassNotFoundException {
441 s.defaultReadObject();
442 count = s.readInt();
443 value = (char[]) s.readObject();
444 }
445
446 }