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 }