001: /*
002: * Copyright 1994-2004 Sun Microsystems, Inc. All Rights Reserved.
003: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004: *
005: * This code is free software; you can redistribute it and/or modify it
006: * under the terms of the GNU General Public License version 2 only, as
007: * published by the Free Software Foundation. Sun designates this
008: * particular file as subject to the "Classpath" exception as provided
009: * by Sun in the LICENSE file that accompanied this code.
010: *
011: * This code is distributed in the hope that it will be useful, but WITHOUT
012: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014: * version 2 for more details (a copy is included in the LICENSE file that
015: * accompanied this code).
016: *
017: * You should have received a copy of the GNU General Public License version
018: * 2 along with this work; if not, write to the Free Software Foundation,
019: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020: *
021: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022: * CA 95054 USA or visit www.sun.com if you need additional information or
023: * have any questions.
024: */
025:
026: package java.lang;
027:
028: /**
029: * A thread-safe, mutable sequence of characters.
030: * A string buffer is like a {@link String}, but can be modified. At any
031: * point in time it contains some particular sequence of characters, but
032: * the length and content of the sequence can be changed through certain
033: * method calls.
034: * <p>
035: * String buffers are safe for use by multiple threads. The methods
036: * are synchronized where necessary so that all the operations on any
037: * particular instance behave as if they occur in some serial order
038: * that is consistent with the order of the method calls made by each of
039: * the individual threads involved.
040: * <p>
041: * The principal operations on a <code>StringBuffer</code> are the
042: * <code>append</code> and <code>insert</code> methods, which are
043: * overloaded so as to accept data of any type. Each effectively
044: * converts a given datum to a string and then appends or inserts the
045: * characters of that string to the string buffer. The
046: * <code>append</code> method always adds these characters at the end
047: * of the buffer; the <code>insert</code> method adds the characters at
048: * a specified point.
049: * <p>
050: * For example, if <code>z</code> refers to a string buffer object
051: * whose current contents are "<code>start</code>", then
052: * the method call <code>z.append("le")</code> would cause the string
053: * buffer to contain "<code>startle</code>", whereas
054: * <code>z.insert(4, "le")</code> would alter the string buffer to
055: * contain "<code>starlet</code>".
056: * <p>
057: * In general, if sb refers to an instance of a <code>StringBuffer</code>,
058: * then <code>sb.append(x)</code> has the same effect as
059: * <code>sb.insert(sb.length(), x)</code>.
060: * <p>
061: * Whenever an operation occurs involving a source sequence (such as
062: * appending or inserting from a source sequence) this class synchronizes
063: * only on the string buffer performing the operation, not on the source.
064: * <p>
065: * Every string buffer has a capacity. As long as the length of the
066: * character sequence contained in the string buffer does not exceed
067: * the capacity, it is not necessary to allocate a new internal
068: * buffer array. If the internal buffer overflows, it is
069: * automatically made larger.
070: *
071: * As of release JDK 5, this class has been supplemented with an equivalent
072: * class designed for use by a single thread, {@link StringBuilder}. The
073: * <tt>StringBuilder</tt> class should generally be used in preference to
074: * this one, as it supports all of the same operations but it is faster, as
075: * it performs no synchronization.
076: *
077: * @author Arthur van Hoff
078: * @version 1.107, 05/05/07
079: * @see java.lang.StringBuilder
080: * @see java.lang.String
081: * @since JDK1.0
082: */
083: public final class StringBuffer extends AbstractStringBuilder implements
084: java.io.Serializable, CharSequence {
085:
086: /** use serialVersionUID from JDK 1.0.2 for interoperability */
087: static final long serialVersionUID = 3388685877147921107L;
088:
089: /**
090: * Constructs a string buffer with no characters in it and an
091: * initial capacity of 16 characters.
092: */
093: public StringBuffer() {
094: super (16);
095: }
096:
097: /**
098: * Constructs a string buffer with no characters in it and
099: * the specified initial capacity.
100: *
101: * @param capacity the initial capacity.
102: * @exception NegativeArraySizeException if the <code>capacity</code>
103: * argument is less than <code>0</code>.
104: */
105: public StringBuffer(int capacity) {
106: super (capacity);
107: }
108:
109: /**
110: * Constructs a string buffer initialized to the contents of the
111: * specified string. The initial capacity of the string buffer is
112: * <code>16</code> plus the length of the string argument.
113: *
114: * @param str the initial contents of the buffer.
115: * @exception NullPointerException if <code>str</code> is <code>null</code>
116: */
117: public StringBuffer(String str) {
118: super (str.length() + 16);
119: append(str);
120: }
121:
122: /**
123: * Constructs a string buffer that contains the same characters
124: * as the specified <code>CharSequence</code>. The initial capacity of
125: * the string buffer is <code>16</code> plus the length of the
126: * <code>CharSequence</code> argument.
127: * <p>
128: * If the length of the specified <code>CharSequence</code> is
129: * less than or equal to zero, then an empty buffer of capacity
130: * <code>16</code> is returned.
131: *
132: * @param seq the sequence to copy.
133: * @exception NullPointerException if <code>seq</code> is <code>null</code>
134: * @since 1.5
135: */
136: public StringBuffer(CharSequence seq) {
137: this (seq.length() + 16);
138: append(seq);
139: }
140:
141: public synchronized int length() {
142: return count;
143: }
144:
145: public synchronized int capacity() {
146: return value.length;
147: }
148:
149: public synchronized void ensureCapacity(int minimumCapacity) {
150: if (minimumCapacity > value.length) {
151: expandCapacity(minimumCapacity);
152: }
153: }
154:
155: /**
156: * @since 1.5
157: */
158: public synchronized void trimToSize() {
159: super .trimToSize();
160: }
161:
162: /**
163: * @throws IndexOutOfBoundsException {@inheritDoc}
164: * @see #length()
165: */
166: public synchronized void setLength(int newLength) {
167: super .setLength(newLength);
168: }
169:
170: /**
171: * @throws IndexOutOfBoundsException {@inheritDoc}
172: * @see #length()
173: */
174: public synchronized char charAt(int index) {
175: if ((index < 0) || (index >= count))
176: throw new StringIndexOutOfBoundsException(index);
177: return value[index];
178: }
179:
180: /**
181: * @since 1.5
182: */
183: public synchronized int codePointAt(int index) {
184: return super .codePointAt(index);
185: }
186:
187: /**
188: * @since 1.5
189: */
190: public synchronized int codePointBefore(int index) {
191: return super .codePointBefore(index);
192: }
193:
194: /**
195: * @since 1.5
196: */
197: public synchronized int codePointCount(int beginIndex, int endIndex) {
198: return super .codePointCount(beginIndex, endIndex);
199: }
200:
201: /**
202: * @since 1.5
203: */
204: public synchronized int offsetByCodePoints(int index,
205: int codePointOffset) {
206: return super .offsetByCodePoints(index, codePointOffset);
207: }
208:
209: /**
210: * @throws NullPointerException {@inheritDoc}
211: * @throws IndexOutOfBoundsException {@inheritDoc}
212: */
213: public synchronized void getChars(int srcBegin, int srcEnd,
214: char dst[], int dstBegin) {
215: super .getChars(srcBegin, srcEnd, dst, dstBegin);
216: }
217:
218: /**
219: * @throws IndexOutOfBoundsException {@inheritDoc}
220: * @see #length()
221: */
222: public synchronized void setCharAt(int index, char ch) {
223: if ((index < 0) || (index >= count))
224: throw new StringIndexOutOfBoundsException(index);
225: value[index] = ch;
226: }
227:
228: /**
229: * @see java.lang.String#valueOf(java.lang.Object)
230: * @see #append(java.lang.String)
231: */
232: public synchronized StringBuffer append(Object obj) {
233: super .append(String.valueOf(obj));
234: return this ;
235: }
236:
237: public synchronized StringBuffer append(String str) {
238: super .append(str);
239: return this ;
240: }
241:
242: /**
243: * Appends the specified <tt>StringBuffer</tt> to this sequence.
244: * <p>
245: * The characters of the <tt>StringBuffer</tt> argument are appended,
246: * in order, to the contents of this <tt>StringBuffer</tt>, increasing the
247: * length of this <tt>StringBuffer</tt> by the length of the argument.
248: * If <tt>sb</tt> is <tt>null</tt>, then the four characters
249: * <tt>"null"</tt> are appended to this <tt>StringBuffer</tt>.
250: * <p>
251: * Let <i>n</i> be the length of the old character sequence, the one
252: * contained in the <tt>StringBuffer</tt> just prior to execution of the
253: * <tt>append</tt> method. Then the character at index <i>k</i> in
254: * the new character sequence is equal to the character at index <i>k</i>
255: * in the old character sequence, if <i>k</i> is less than <i>n</i>;
256: * otherwise, it is equal to the character at index <i>k-n</i> in the
257: * argument <code>sb</code>.
258: * <p>
259: * This method synchronizes on <code>this</code> (the destination)
260: * object but does not synchronize on the source (<code>sb</code>).
261: *
262: * @param sb the <tt>StringBuffer</tt> to append.
263: * @return a reference to this object.
264: * @since 1.4
265: */
266: public synchronized StringBuffer append(StringBuffer sb) {
267: super .append(sb);
268: return this ;
269: }
270:
271: /**
272: * Appends the specified <code>CharSequence</code> to this
273: * sequence.
274: * <p>
275: * The characters of the <code>CharSequence</code> argument are appended,
276: * in order, increasing the length of this sequence by the length of the
277: * argument.
278: *
279: * <p>The result of this method is exactly the same as if it were an
280: * invocation of this.append(s, 0, s.length());
281: *
282: * <p>This method synchronizes on this (the destination)
283: * object but does not synchronize on the source (<code>s</code>).
284: *
285: * <p>If <code>s</code> is <code>null</code>, then the four characters
286: * <code>"null"</code> are appended.
287: *
288: * @param s the <code>CharSequence</code> to append.
289: * @return a reference to this object.
290: * @since 1.5
291: */
292: public StringBuffer append(CharSequence s) {
293: // Note, synchronization achieved via other invocations
294: if (s == null)
295: s = "null";
296: if (s instanceof String)
297: return this .append((String) s);
298: if (s instanceof StringBuffer)
299: return this .append((StringBuffer) s);
300: return this .append(s, 0, s.length());
301: }
302:
303: /**
304: * @throws IndexOutOfBoundsException {@inheritDoc}
305: * @since 1.5
306: */
307: public synchronized StringBuffer append(CharSequence s, int start,
308: int end) {
309: super .append(s, start, end);
310: return this ;
311: }
312:
313: public synchronized StringBuffer append(char str[]) {
314: super .append(str);
315: return this ;
316: }
317:
318: public synchronized StringBuffer append(char str[], int offset,
319: int len) {
320: super .append(str, offset, len);
321: return this ;
322: }
323:
324: /**
325: * @see java.lang.String#valueOf(boolean)
326: * @see #append(java.lang.String)
327: */
328: public synchronized StringBuffer append(boolean b) {
329: super .append(b);
330: return this ;
331: }
332:
333: public synchronized StringBuffer append(char c) {
334: super .append(c);
335: return this ;
336: }
337:
338: /**
339: * @see java.lang.String#valueOf(int)
340: * @see #append(java.lang.String)
341: */
342: public synchronized StringBuffer append(int i) {
343: super .append(i);
344: return this ;
345: }
346:
347: /**
348: * @since 1.5
349: */
350: public synchronized StringBuffer appendCodePoint(int codePoint) {
351: super .appendCodePoint(codePoint);
352: return this ;
353: }
354:
355: /**
356: * @see java.lang.String#valueOf(long)
357: * @see #append(java.lang.String)
358: */
359: public synchronized StringBuffer append(long lng) {
360: super .append(lng);
361: return this ;
362: }
363:
364: /**
365: * @see java.lang.String#valueOf(float)
366: * @see #append(java.lang.String)
367: */
368: public synchronized StringBuffer append(float f) {
369: super .append(f);
370: return this ;
371: }
372:
373: /**
374: * @see java.lang.String#valueOf(double)
375: * @see #append(java.lang.String)
376: */
377: public synchronized StringBuffer append(double d) {
378: super .append(d);
379: return this ;
380: }
381:
382: /**
383: * @throws StringIndexOutOfBoundsException {@inheritDoc}
384: * @since 1.2
385: */
386: public synchronized StringBuffer delete(int start, int end) {
387: super .delete(start, end);
388: return this ;
389: }
390:
391: /**
392: * @throws StringIndexOutOfBoundsException {@inheritDoc}
393: * @since 1.2
394: */
395: public synchronized StringBuffer deleteCharAt(int index) {
396: super .deleteCharAt(index);
397: return this ;
398: }
399:
400: /**
401: * @throws StringIndexOutOfBoundsException {@inheritDoc}
402: * @since 1.2
403: */
404: public synchronized StringBuffer replace(int start, int end,
405: String str) {
406: super .replace(start, end, str);
407: return this ;
408: }
409:
410: /**
411: * @throws StringIndexOutOfBoundsException {@inheritDoc}
412: * @since 1.2
413: */
414: public synchronized String substring(int start) {
415: return substring(start, count);
416: }
417:
418: /**
419: * @throws IndexOutOfBoundsException {@inheritDoc}
420: * @since 1.4
421: */
422: public synchronized CharSequence subSequence(int start, int end) {
423: return super .substring(start, end);
424: }
425:
426: /**
427: * @throws StringIndexOutOfBoundsException {@inheritDoc}
428: * @since 1.2
429: */
430: public synchronized String substring(int start, int end) {
431: return super .substring(start, end);
432: }
433:
434: /**
435: * @throws StringIndexOutOfBoundsException {@inheritDoc}
436: * @since 1.2
437: */
438: public synchronized StringBuffer insert(int index, char str[],
439: int offset, int len) {
440: super .insert(index, str, offset, len);
441: return this ;
442: }
443:
444: /**
445: * @throws StringIndexOutOfBoundsException {@inheritDoc}
446: * @see java.lang.String#valueOf(java.lang.Object)
447: * @see #insert(int, java.lang.String)
448: * @see #length()
449: */
450: public synchronized StringBuffer insert(int offset, Object obj) {
451: super .insert(offset, String.valueOf(obj));
452: return this ;
453: }
454:
455: /**
456: * @throws StringIndexOutOfBoundsException {@inheritDoc}
457: * @see #length()
458: */
459: public synchronized StringBuffer insert(int offset, String str) {
460: super .insert(offset, str);
461: return this ;
462: }
463:
464: /**
465: * @throws StringIndexOutOfBoundsException {@inheritDoc}
466: */
467: public synchronized StringBuffer insert(int offset, char str[]) {
468: super .insert(offset, str);
469: return this ;
470: }
471:
472: /**
473: * @throws IndexOutOfBoundsException {@inheritDoc}
474: * @since 1.5
475: */
476: public StringBuffer insert(int dstOffset, CharSequence s) {
477: // Note, synchronization achieved via other invocations
478: if (s == null)
479: s = "null";
480: if (s instanceof String)
481: return this .insert(dstOffset, (String) s);
482: return this .insert(dstOffset, s, 0, s.length());
483: }
484:
485: /**
486: * @throws IndexOutOfBoundsException {@inheritDoc}
487: * @since 1.5
488: */
489: public synchronized StringBuffer insert(int dstOffset,
490: CharSequence s, int start, int end) {
491: super .insert(dstOffset, s, start, end);
492: return this ;
493: }
494:
495: /**
496: * @throws StringIndexOutOfBoundsException {@inheritDoc}
497: * @see java.lang.String#valueOf(boolean)
498: * @see #insert(int, java.lang.String)
499: * @see #length()
500: */
501: public StringBuffer insert(int offset, boolean b) {
502: return insert(offset, String.valueOf(b));
503: }
504:
505: /**
506: * @throws IndexOutOfBoundsException {@inheritDoc}
507: * @see #length()
508: */
509: public synchronized StringBuffer insert(int offset, char c) {
510: super .insert(offset, c);
511: return this ;
512: }
513:
514: /**
515: * @throws StringIndexOutOfBoundsException {@inheritDoc}
516: * @see java.lang.String#valueOf(int)
517: * @see #insert(int, java.lang.String)
518: * @see #length()
519: */
520: public StringBuffer insert(int offset, int i) {
521: return insert(offset, String.valueOf(i));
522: }
523:
524: /**
525: * @throws StringIndexOutOfBoundsException {@inheritDoc}
526: * @see java.lang.String#valueOf(long)
527: * @see #insert(int, java.lang.String)
528: * @see #length()
529: */
530: public StringBuffer insert(int offset, long l) {
531: return insert(offset, String.valueOf(l));
532: }
533:
534: /**
535: * @throws StringIndexOutOfBoundsException {@inheritDoc}
536: * @see java.lang.String#valueOf(float)
537: * @see #insert(int, java.lang.String)
538: * @see #length()
539: */
540: public StringBuffer insert(int offset, float f) {
541: return insert(offset, String.valueOf(f));
542: }
543:
544: /**
545: * @throws StringIndexOutOfBoundsException {@inheritDoc}
546: * @see java.lang.String#valueOf(double)
547: * @see #insert(int, java.lang.String)
548: * @see #length()
549: */
550: public StringBuffer insert(int offset, double d) {
551: return insert(offset, String.valueOf(d));
552: }
553:
554: /**
555: * @throws NullPointerException {@inheritDoc}
556: * @since 1.4
557: */
558: public int indexOf(String str) {
559: return indexOf(str, 0);
560: }
561:
562: /**
563: * @throws NullPointerException {@inheritDoc}
564: * @since 1.4
565: */
566: public synchronized int indexOf(String str, int fromIndex) {
567: return String.indexOf(value, 0, count, str.toCharArray(), 0,
568: str.length(), fromIndex);
569: }
570:
571: /**
572: * @throws NullPointerException {@inheritDoc}
573: * @since 1.4
574: */
575: public int lastIndexOf(String str) {
576: // Note, synchronization achieved via other invocations
577: return lastIndexOf(str, count);
578: }
579:
580: /**
581: * @throws NullPointerException {@inheritDoc}
582: * @since 1.4
583: */
584: public synchronized int lastIndexOf(String str, int fromIndex) {
585: return String.lastIndexOf(value, 0, count, str.toCharArray(),
586: 0, str.length(), fromIndex);
587: }
588:
589: /**
590: * @since JDK1.0.2
591: */
592: public synchronized StringBuffer reverse() {
593: super .reverse();
594: return this ;
595: }
596:
597: public synchronized String toString() {
598: return new String(value, 0, count);
599: }
600:
601: /**
602: * Serializable fields for StringBuffer.
603: *
604: * @serialField value char[]
605: * The backing character array of this StringBuffer.
606: * @serialField count int
607: * The number of characters in this StringBuffer.
608: * @serialField shared boolean
609: * A flag indicating whether the backing array is shared.
610: * The value is ignored upon deserialization.
611: */
612: private static final java.io.ObjectStreamField[] serialPersistentFields = {
613: new java.io.ObjectStreamField("value", char[].class),
614: new java.io.ObjectStreamField("count", Integer.TYPE),
615: new java.io.ObjectStreamField("shared", Boolean.TYPE), };
616:
617: /**
618: * readObject is called to restore the state of the StringBuffer from
619: * a stream.
620: */
621: private synchronized void writeObject(java.io.ObjectOutputStream s)
622: throws java.io.IOException {
623: java.io.ObjectOutputStream.PutField fields = s.putFields();
624: fields.put("value", value);
625: fields.put("count", count);
626: fields.put("shared", false);
627: s.writeFields();
628: }
629:
630: /**
631: * readObject is called to restore the state of the StringBuffer from
632: * a stream.
633: */
634: private void readObject(java.io.ObjectInputStream s)
635: throws java.io.IOException, ClassNotFoundException {
636: java.io.ObjectInputStream.GetField fields = s.readFields();
637: value = (char[]) fields.get("value", null);
638: count = (int) fields.get("count", 0);
639: }
640: }
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