1 /*
2 * Copyright 2003-2004 Sun Microsystems, Inc. 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. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any 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 /**
128 * @see java.lang.String#valueOf(java.lang.Object)
129 * @see #append(java.lang.String)
130 */
131 public StringBuilder append(Object obj) {
132 return append(String.valueOf(obj));
133 }
134
135 public StringBuilder append(String str) {
136 super.append(str);
137 return this;
138 }
139
140 // Appends the specified string builder to this sequence.
141 private StringBuilder append(StringBuilder sb) {
142 if (sb == null)
143 return append("null");
144 int len = sb.length();
145 int newcount = count + len;
146 if (newcount > value.length)
147 expandCapacity(newcount);
148 sb.getChars(0, len, value, count);
149 count = newcount;
150 return this;
151 }
152
153 /**
154 * Appends the specified <tt>StringBuffer</tt> to this sequence.
155 * <p>
156 * The characters of the <tt>StringBuffer</tt> argument are appended,
157 * in order, to this sequence, increasing the
158 * length of this sequence by the length of the argument.
159 * If <tt>sb</tt> is <tt>null</tt>, then the four characters
160 * <tt>"null"</tt> are appended to this sequence.
161 * <p>
162 * Let <i>n</i> be the length of this character sequence just prior to
163 * execution of the <tt>append</tt> method. Then the character at index
164 * <i>k</i> in the new character sequence is equal to the character at
165 * index <i>k</i> in the old character sequence, if <i>k</i> is less than
166 * <i>n</i>; otherwise, it is equal to the character at index <i>k-n</i>
167 * in the argument <code>sb</code>.
168 *
169 * @param sb the <tt>StringBuffer</tt> to append.
170 * @return a reference to this object.
171 */
172 public StringBuilder append(StringBuffer sb) {
173 super.append(sb);
174 return this;
175 }
176
177 /**
178 * @throws IndexOutOfBoundsException {@inheritDoc}
179 */
180 public StringBuilder append(CharSequence s) {
181 if (s == null)
182 s = "null";
183 if (s instanceof String)
184 return this.append((String)s);
185 if (s instanceof StringBuffer)
186 return this.append((StringBuffer)s);
187 if (s instanceof StringBuilder)
188 return this.append((StringBuilder)s);
189 return this.append(s, 0, s.length());
190 }
191
192 /**
193 * @throws IndexOutOfBoundsException {@inheritDoc}
194 */
195 public StringBuilder append(CharSequence s, int start, int end) {
196 super.append(s, start, end);
197 return this;
198 }
199
200 public StringBuilder append(char str[]) {
201 super.append(str);
202 return this;
203 }
204
205 public StringBuilder append(char str[], int offset, int len) {
206 super.append(str, offset, len);
207 return this;
208 }
209
210 /**
211 * @see java.lang.String#valueOf(boolean)
212 * @see #append(java.lang.String)
213 */
214 public StringBuilder append(boolean b) {
215 super.append(b);
216 return this;
217 }
218
219 public StringBuilder append(char c) {
220 super.append(c);
221 return this;
222 }
223
224 /**
225 * @see java.lang.String#valueOf(int)
226 * @see #append(java.lang.String)
227 */
228 public StringBuilder append(int i) {
229 super.append(i);
230 return this;
231 }
232
233 /**
234 * @see java.lang.String#valueOf(long)
235 * @see #append(java.lang.String)
236 */
237 public StringBuilder append(long lng) {
238 super.append(lng);
239 return this;
240 }
241
242 /**
243 * @see java.lang.String#valueOf(float)
244 * @see #append(java.lang.String)
245 */
246 public StringBuilder append(float f) {
247 super.append(f);
248 return this;
249 }
250
251 /**
252 * @see java.lang.String#valueOf(double)
253 * @see #append(java.lang.String)
254 */
255 public StringBuilder append(double d) {
256 super.append(d);
257 return this;
258 }
259
260 /**
261 * @since 1.5
262 */
263 public StringBuilder appendCodePoint(int codePoint) {
264 super.appendCodePoint(codePoint);
265 return this;
266 }
267
268 /**
269 * @throws StringIndexOutOfBoundsException {@inheritDoc}
270 */
271 public StringBuilder delete(int start, int end) {
272 super.delete(start, end);
273 return this;
274 }
275
276 /**
277 * @throws StringIndexOutOfBoundsException {@inheritDoc}
278 */
279 public StringBuilder deleteCharAt(int index) {
280 super.deleteCharAt(index);
281 return this;
282 }
283
284 /**
285 * @throws StringIndexOutOfBoundsException {@inheritDoc}
286 */
287 public StringBuilder replace(int start, int end, String str) {
288 super.replace(start, end, str);
289 return this;
290 }
291
292 /**
293 * @throws StringIndexOutOfBoundsException {@inheritDoc}
294 */
295 public StringBuilder insert(int index, char str[], int offset,
296 int len)
297 {
298 super.insert(index, str, offset, len);
299 return this;
300 }
301
302 /**
303 * @throws StringIndexOutOfBoundsException {@inheritDoc}
304 * @see java.lang.String#valueOf(java.lang.Object)
305 * @see #insert(int, java.lang.String)
306 * @see #length()
307 */
308 public StringBuilder insert(int offset, Object obj) {
309 return insert(offset, String.valueOf(obj));
310 }
311
312 /**
313 * @throws StringIndexOutOfBoundsException {@inheritDoc}
314 * @see #length()
315 */
316 public StringBuilder insert(int offset, String str) {
317 super.insert(offset, str);
318 return this;
319 }
320
321 /**
322 * @throws StringIndexOutOfBoundsException {@inheritDoc}
323 */
324 public StringBuilder insert(int offset, char str[]) {
325 super.insert(offset, str);
326 return this;
327 }
328
329 /**
330 * @throws IndexOutOfBoundsException {@inheritDoc}
331 */
332 public StringBuilder insert(int dstOffset, CharSequence s) {
333 if (s == null)
334 s = "null";
335 if (s instanceof String)
336 return this.insert(dstOffset, (String)s);
337 return this.insert(dstOffset, s, 0, s.length());
338 }
339
340 /**
341 * @throws IndexOutOfBoundsException {@inheritDoc}
342 */
343 public StringBuilder insert(int dstOffset, CharSequence s,
344 int start, int end)
345 {
346 super.insert(dstOffset, s, start, end);
347 return this;
348 }
349
350 /**
351 * @throws StringIndexOutOfBoundsException {@inheritDoc}
352 * @see java.lang.String#valueOf(boolean)
353 * @see #insert(int, java.lang.String)
354 * @see #length()
355 */
356 public StringBuilder insert(int offset, boolean b) {
357 super.insert(offset, b);
358 return this;
359 }
360
361 /**
362 * @throws IndexOutOfBoundsException {@inheritDoc}
363 * @see #length()
364 */
365 public StringBuilder insert(int offset, char c) {
366 super.insert(offset, c);
367 return this;
368 }
369
370 /**
371 * @throws StringIndexOutOfBoundsException {@inheritDoc}
372 * @see java.lang.String#valueOf(int)
373 * @see #insert(int, java.lang.String)
374 * @see #length()
375 */
376 public StringBuilder insert(int offset, int i) {
377 return insert(offset, String.valueOf(i));
378 }
379
380 /**
381 * @throws StringIndexOutOfBoundsException {@inheritDoc}
382 * @see java.lang.String#valueOf(long)
383 * @see #insert(int, java.lang.String)
384 * @see #length()
385 */
386 public StringBuilder insert(int offset, long l) {
387 return insert(offset, String.valueOf(l));
388 }
389
390 /**
391 * @throws StringIndexOutOfBoundsException {@inheritDoc}
392 * @see java.lang.String#valueOf(float)
393 * @see #insert(int, java.lang.String)
394 * @see #length()
395 */
396 public StringBuilder insert(int offset, float f) {
397 return insert(offset, String.valueOf(f));
398 }
399
400 /**
401 * @throws StringIndexOutOfBoundsException {@inheritDoc}
402 * @see java.lang.String#valueOf(double)
403 * @see #insert(int, java.lang.String)
404 * @see #length()
405 */
406 public StringBuilder insert(int offset, double d) {
407 return insert(offset, String.valueOf(d));
408 }
409
410 /**
411 * @throws NullPointerException {@inheritDoc}
412 */
413 public int indexOf(String str) {
414 return indexOf(str, 0);
415 }
416
417 /**
418 * @throws NullPointerException {@inheritDoc}
419 */
420 public int indexOf(String str, int fromIndex) {
421 return String.indexOf(value, 0, count,
422 str.toCharArray(), 0, str.length(), fromIndex);
423 }
424
425 /**
426 * @throws NullPointerException {@inheritDoc}
427 */
428 public int lastIndexOf(String str) {
429 return lastIndexOf(str, count);
430 }
431
432 /**
433 * @throws NullPointerException {@inheritDoc}
434 */
435 public int lastIndexOf(String str, int fromIndex) {
436 return String.lastIndexOf(value, 0, count,
437 str.toCharArray(), 0, str.length(), fromIndex);
438 }
439
440 public StringBuilder reverse() {
441 super.reverse();
442 return this;
443 }
444
445 public String toString() {
446 // Create a copy, don't share the array
447 return new String(value, 0, count);
448 }
449
450 /**
451 * Save the state of the <tt>StringBuilder</tt> instance to a stream
452 * (that is, serialize it).
453 *
454 * @serialData the number of characters currently stored in the string
455 * builder (<tt>int</tt>), followed by the characters in the
456 * string builder (<tt>char[]</tt>). The length of the
457 * <tt>char</tt> array may be greater than the number of
458 * characters currently stored in the string builder, in which
459 * case extra characters are ignored.
460 */
461 private void writeObject(java.io.ObjectOutputStream s)
462 throws java.io.IOException {
463 s.defaultWriteObject();
464 s.writeInt(count);
465 s.writeObject(value);
466 }
467
468 /**
469 * readObject is called to restore the state of the StringBuffer from
470 * a stream.
471 */
472 private void readObject(java.io.ObjectInputStream s)
473 throws java.io.IOException, ClassNotFoundException {
474 s.defaultReadObject();
475 count = s.readInt();
476 value = (char[]) s.readObject();
477 }
478
479 }
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