1 /* 2 * Copyright (c) 2003, 2013, 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 import jdk.internal.HotSpotIntrinsicCandidate; 29 30 /** 31 * A mutable sequence of characters. This class provides an API compatible 32 * with {@code StringBuffer}, but with no guarantee of synchronization. 33 * This class is designed for use as a drop-in replacement for 34 * {@code StringBuffer} in places where the string buffer was being 35 * used by a single thread (as is generally the case). Where possible, 36 * it is recommended that this class be used in preference to 37 * {@code StringBuffer} as it will be faster under most implementations. 38 * 39 * <p>The principal operations on a {@code StringBuilder} are the 40 * {@code append} and {@code insert} methods, which are 41 * overloaded so as to accept data of any type. Each effectively 42 * converts a given datum to a string and then appends or inserts the 43 * characters of that string to the string builder. The 44 * {@code append} method always adds these characters at the end 45 * of the builder; the {@code insert} method adds the characters at 46 * a specified point. 47 * <p> 48 * For example, if {@code z} refers to a string builder object 49 * whose current contents are "{@code start}", then 50 * the method call {@code z.append("le")} would cause the string 51 * builder to contain "{@code startle}", whereas 52 * {@code z.insert(4, "le")} would alter the string builder to 53 * contain "{@code starlet}". 54 * <p> 55 * In general, if sb refers to an instance of a {@code StringBuilder}, 56 * then {@code sb.append(x)} has the same effect as 57 * {@code sb.insert(sb.length(), x)}. 58 * <p> 59 * Every string builder has a capacity. As long as the length of the 60 * character sequence contained in the string builder does not exceed 61 * the capacity, it is not necessary to allocate a new internal 62 * buffer. If the internal buffer overflows, it is automatically made larger. 63 * 64 * <p>Instances of {@code StringBuilder} are not safe for 65 * use by multiple threads. If such synchronization is required then it is 66 * recommended that {@link java.lang.StringBuffer} be used. 67 * 68 * <p>Unless otherwise noted, passing a {@code null} argument to a constructor 69 * or method in this class will cause a {@link NullPointerException} to be 70 * thrown. 71 * 72 * @author Michael McCloskey 73 * @see java.lang.StringBuffer 74 * @see java.lang.String 75 * @since 1.5 76 */ 77 public final class StringBuilder 78 extends AbstractStringBuilder 79 implements java.io.Serializable, CharSequence 80 { 81 82 /** use serialVersionUID for interoperability */ 83 static final long serialVersionUID = 4383685877147921099L; 84 85 /** 86 * Constructs a string builder with no characters in it and an 87 * initial capacity of 16 characters. 88 */ 89 @HotSpotIntrinsicCandidate 90 public StringBuilder() { 91 super(16); 92 } 93 94 /** 95 * Constructs a string builder with no characters in it and an 96 * initial capacity specified by the {@code capacity} argument. 97 * 98 * @param capacity the initial capacity. 99 * @throws NegativeArraySizeException if the {@code capacity} 100 * argument is less than {@code 0}. 101 */ 102 @HotSpotIntrinsicCandidate 103 public StringBuilder(int capacity) { 104 super(capacity); 105 } 106 107 /** 108 * Constructs a string builder initialized to the contents of the 109 * specified string. The initial capacity of the string builder is 110 * {@code 16} plus the length of the string argument. 111 * 112 * @param str the initial contents of the buffer. 113 */ 114 @HotSpotIntrinsicCandidate 115 public StringBuilder(String str) { 116 super(str.length() + 16); 117 append(str); 118 } 119 120 /** 121 * Constructs a string builder that contains the same characters 122 * as the specified {@code CharSequence}. The initial capacity of 123 * the string builder is {@code 16} plus the length of the 124 * {@code CharSequence} argument. 125 * 126 * @param seq the sequence to copy. 127 */ 128 public StringBuilder(CharSequence seq) { 129 this(seq.length() + 16); 130 append(seq); 131 } 132 133 @Override 134 public StringBuilder append(Object obj) { 135 return append(String.valueOf(obj)); 136 } 137 138 @Override 139 @HotSpotIntrinsicCandidate 140 public StringBuilder append(String str) { 141 super.append(str); 142 return this; 143 } 144 145 /** 146 * Appends the specified {@code StringBuffer} to this sequence. 147 * <p> 148 * The characters of the {@code StringBuffer} argument are appended, 149 * in order, to this sequence, increasing the 150 * length of this sequence by the length of the argument. 151 * If {@code sb} is {@code null}, then the four characters 152 * {@code "null"} are appended to this sequence. 153 * <p> 154 * Let <i>n</i> be the length of this character sequence just prior to 155 * execution of the {@code append} method. Then the character at index 156 * <i>k</i> in the new character sequence is equal to the character at 157 * index <i>k</i> in the old character sequence, if <i>k</i> is less than 158 * <i>n</i>; otherwise, it is equal to the character at index <i>k-n</i> 159 * in the argument {@code sb}. 160 * 161 * @param sb the {@code StringBuffer} to append. 162 * @return a reference to this object. 163 */ 164 public StringBuilder append(StringBuffer sb) { 165 super.append(sb); 166 return this; 167 } 168 169 @Override 170 public StringBuilder append(CharSequence s) { 171 super.append(s); 172 return this; 173 } 174 175 /** 176 * @throws IndexOutOfBoundsException {@inheritDoc} 177 */ 178 @Override 179 public StringBuilder append(CharSequence s, int start, int end) { 180 super.append(s, start, end); 181 return this; 182 } 183 184 @Override 185 public StringBuilder append(char[] str) { 186 super.append(str); 187 return this; 188 } 189 190 /** 191 * @throws IndexOutOfBoundsException {@inheritDoc} 192 */ 193 @Override 194 public StringBuilder append(char[] str, int offset, int len) { 195 super.append(str, offset, len); 196 return this; 197 } 198 199 @Override 200 public StringBuilder append(boolean b) { 201 super.append(b); 202 return this; 203 } 204 205 @Override 206 @HotSpotIntrinsicCandidate 207 public StringBuilder append(char c) { 208 super.append(c); 209 return this; 210 } 211 212 @Override 213 @HotSpotIntrinsicCandidate 214 public StringBuilder append(int i) { 215 super.append(i); 216 return this; 217 } 218 219 @Override 220 public StringBuilder append(long lng) { 221 super.append(lng); 222 return this; 223 } 224 225 @Override 226 public StringBuilder append(float f) { 227 super.append(f); 228 return this; 229 } 230 231 @Override 232 public StringBuilder append(double d) { 233 super.append(d); 234 return this; 235 } 236 237 @Override 238 public StringBuilder appendN(char c, int n) { 239 super.appendN(c, n); 240 return this; 241 } 242 243 /** 244 * @since 1.5 245 */ 246 @Override 247 public StringBuilder appendCodePoint(int codePoint) { 248 super.appendCodePoint(codePoint); 249 return this; 250 } 251 252 /** 253 * @throws StringIndexOutOfBoundsException {@inheritDoc} 254 */ 255 @Override 256 public StringBuilder delete(int start, int end) { 257 super.delete(start, end); 258 return this; 259 } 260 261 /** 262 * @throws StringIndexOutOfBoundsException {@inheritDoc} 263 */ 264 @Override 265 public StringBuilder deleteCharAt(int index) { 266 super.deleteCharAt(index); 267 return this; 268 } 269 270 /** 271 * @throws StringIndexOutOfBoundsException {@inheritDoc} 272 */ 273 @Override 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 @Override 283 public StringBuilder insert(int index, char[] str, int offset, 284 int len) 285 { 286 super.insert(index, str, offset, len); 287 return this; 288 } 289 290 /** 291 * @throws StringIndexOutOfBoundsException {@inheritDoc} 292 */ 293 @Override 294 public StringBuilder insert(int offset, Object obj) { 295 super.insert(offset, obj); 296 return this; 297 } 298 299 /** 300 * @throws StringIndexOutOfBoundsException {@inheritDoc} 301 */ 302 @Override 303 public StringBuilder insert(int offset, String str) { 304 super.insert(offset, str); 305 return this; 306 } 307 308 /** 309 * @throws StringIndexOutOfBoundsException {@inheritDoc} 310 */ 311 @Override 312 public StringBuilder insert(int offset, char[] str) { 313 super.insert(offset, str); 314 return this; 315 } 316 317 /** 318 * @throws IndexOutOfBoundsException {@inheritDoc} 319 */ 320 @Override 321 public StringBuilder insert(int dstOffset, CharSequence s) { 322 super.insert(dstOffset, s); 323 return this; 324 } 325 326 /** 327 * @throws IndexOutOfBoundsException {@inheritDoc} 328 */ 329 @Override 330 public StringBuilder insert(int dstOffset, CharSequence s, 331 int start, int end) 332 { 333 super.insert(dstOffset, s, start, end); 334 return this; 335 } 336 337 /** 338 * @throws StringIndexOutOfBoundsException {@inheritDoc} 339 */ 340 @Override 341 public StringBuilder insert(int offset, boolean b) { 342 super.insert(offset, b); 343 return this; 344 } 345 346 /** 347 * @throws IndexOutOfBoundsException {@inheritDoc} 348 */ 349 @Override 350 public StringBuilder insert(int offset, char c) { 351 super.insert(offset, c); 352 return this; 353 } 354 355 /** 356 * @throws StringIndexOutOfBoundsException {@inheritDoc} 357 */ 358 @Override 359 public StringBuilder insert(int offset, int i) { 360 super.insert(offset, i); 361 return this; 362 } 363 364 /** 365 * @throws StringIndexOutOfBoundsException {@inheritDoc} 366 */ 367 @Override 368 public StringBuilder insert(int offset, long l) { 369 super.insert(offset, l); 370 return this; 371 } 372 373 /** 374 * @throws StringIndexOutOfBoundsException {@inheritDoc} 375 */ 376 @Override 377 public StringBuilder insert(int offset, float f) { 378 super.insert(offset, f); 379 return this; 380 } 381 382 /** 383 * @throws StringIndexOutOfBoundsException {@inheritDoc} 384 */ 385 @Override 386 public StringBuilder insert(int offset, double d) { 387 super.insert(offset, d); 388 return this; 389 } 390 391 @Override 392 public int indexOf(String str) { 393 return super.indexOf(str); 394 } 395 396 @Override 397 public int indexOf(String str, int fromIndex) { 398 return super.indexOf(str, fromIndex); 399 } 400 401 @Override 402 public int lastIndexOf(String str) { 403 return super.lastIndexOf(str); 404 } 405 406 @Override 407 public int lastIndexOf(String str, int fromIndex) { 408 return super.lastIndexOf(str, fromIndex); 409 } 410 411 @Override 412 public StringBuilder reverse() { 413 super.reverse(); 414 return this; 415 } 416 417 @Override 418 @HotSpotIntrinsicCandidate 419 public String toString() { 420 // Create a copy, don't share the array 421 return isLatin1() ? StringLatin1.newString(value, 0, count) 422 : StringUTF16.newString(value, 0, count); 423 } 424 425 /** 426 * Save the state of the {@code StringBuilder} instance to a stream 427 * (that is, serialize it). 428 * 429 * @serialData the number of characters currently stored in the string 430 * builder ({@code int}), followed by the characters in the 431 * string builder ({@code char[]}). The length of the 432 * {@code char} array may be greater than the number of 433 * characters currently stored in the string builder, in which 434 * case extra characters are ignored. 435 */ 436 private void writeObject(java.io.ObjectOutputStream s) 437 throws java.io.IOException { 438 s.defaultWriteObject(); 439 s.writeInt(count); 440 char[] val = new char[capacity()]; 441 if (isLatin1()) { 442 StringLatin1.getChars(value, 0, count, val, 0); 443 } else { 444 StringUTF16.getChars(value, 0, count, val, 0); 445 } 446 s.writeObject(val); 447 } 448 449 /** 450 * readObject is called to restore the state of the StringBuffer from 451 * a stream. 452 */ 453 private void readObject(java.io.ObjectInputStream s) 454 throws java.io.IOException, ClassNotFoundException { 455 s.defaultReadObject(); 456 count = s.readInt(); 457 char[] val = (char[]) s.readObject(); 458 initBytes(val, 0, val.length); 459 } 460 461 }