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