1/* 2 * Copyright (c) 1994, 2017, 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 26package java.lang; 27 28import java.lang.annotation.Native; 29import java.util.Objects; 30import jdk.internal.HotSpotIntrinsicCandidate; 31import jdk.internal.misc.VM; 32 33import static java.lang.String.COMPACT_STRINGS; 34import static java.lang.String.LATIN1; 35import static java.lang.String.UTF16; 36 37/** 38 * The {@code Integer} class wraps a value of the primitive type 39 * {@code int} in an object. An object of type {@code Integer} 40 * contains a single field whose type is {@code int}. 41 * 42 * <p>In addition, this class provides several methods for converting 43 * an {@code int} to a {@code String} and a {@code String} to an 44 * {@code int}, as well as other constants and methods useful when 45 * dealing with an {@code int}. 46 * 47 * <p>Implementation note: The implementations of the "bit twiddling" 48 * methods (such as {@link #highestOneBit(int) highestOneBit} and 49 * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are 50 * based on material from Henry S. Warren, Jr.'s <i>Hacker's 51 * Delight</i>, (Addison Wesley, 2002). 52 * 53 * @author Lee Boynton 54 * @author Arthur van Hoff 55 * @author Josh Bloch 56 * @author Joseph D. Darcy 57 * @since 1.0 58 */ 59public final class Integer extends Number implements Comparable<Integer> { 60 /** 61 * A constant holding the minimum value an {@code int} can 62 * have, -2<sup>31</sup>. 63 */ 64 @Native public static final int MIN_VALUE = 0x80000000; 65 66 /** 67 * A constant holding the maximum value an {@code int} can 68 * have, 2<sup>31</sup>-1. 69 */ 70 @Native public static final int MAX_VALUE = 0x7fffffff; 71 72 /** 73 * The {@code Class} instance representing the primitive type 74 * {@code int}. 75 * 76 * @since 1.1 77 */ 78 @SuppressWarnings("unchecked") 79 public static final Class<Integer> TYPE = (Class<Integer>) Class.getPrimitiveClass("int"); 80 81 /** 82 * All possible chars for representing a number as a String 83 */ 84 static final char[] digits = { 85 '0' , '1' , '2' , '3' , '4' , '5' , 86 '6' , '7' , '8' , '9' , 'a' , 'b' , 87 'c' , 'd' , 'e' , 'f' , 'g' , 'h' , 88 'i' , 'j' , 'k' , 'l' , 'm' , 'n' , 89 'o' , 'p' , 'q' , 'r' , 's' , 't' , 90 'u' , 'v' , 'w' , 'x' , 'y' , 'z' 91 }; 92 93 /** 94 * Returns a string representation of the first argument in the 95 * radix specified by the second argument. 96 * 97 * <p>If the radix is smaller than {@code Character.MIN_RADIX} 98 * or larger than {@code Character.MAX_RADIX}, then the radix 99 * {@code 10} is used instead. 100 * 101 * <p>If the first argument is negative, the first element of the 102 * result is the ASCII minus character {@code '-'} 103 * ({@code '\u005Cu002D'}). If the first argument is not 104 * negative, no sign character appears in the result. 105 * 106 * <p>The remaining characters of the result represent the magnitude 107 * of the first argument. If the magnitude is zero, it is 108 * represented by a single zero character {@code '0'} 109 * ({@code '\u005Cu0030'}); otherwise, the first character of 110 * the representation of the magnitude will not be the zero 111 * character. The following ASCII characters are used as digits: 112 * 113 * <blockquote> 114 * {@code 0123456789abcdefghijklmnopqrstuvwxyz} 115 * </blockquote> 116 * 117 * These are {@code '\u005Cu0030'} through 118 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through 119 * {@code '\u005Cu007A'}. If {@code radix} is 120 * <var>N</var>, then the first <var>N</var> of these characters 121 * are used as radix-<var>N</var> digits in the order shown. Thus, 122 * the digits for hexadecimal (radix 16) are 123 * {@code 0123456789abcdef}. If uppercase letters are 124 * desired, the {@link java.lang.String#toUpperCase()} method may 125 * be called on the result: 126 * 127 * <blockquote> 128 * {@code Integer.toString(n, 16).toUpperCase()} 129 * </blockquote> 130 * 131 * @param i an integer to be converted to a string. 132 * @param radix the radix to use in the string representation. 133 * @return a string representation of the argument in the specified radix. 134 * @see java.lang.Character#MAX_RADIX 135 * @see java.lang.Character#MIN_RADIX 136 */ 137 public static String toString(int i, int radix) { 138 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX) 139 radix = 10; 140 141 /* Use the faster version */ 142 if (radix == 10) { 143 return toString(i); 144 } 145 146 if (COMPACT_STRINGS) { 147 byte[] buf = new byte[33]; 148 boolean negative = (i < 0); 149 int charPos = 32; 150 151 if (!negative) { 152 i = -i; 153 } 154 155 while (i <= -radix) { 156 buf[charPos--] = (byte)digits[-(i % radix)]; 157 i = i / radix; 158 } 159 buf[charPos] = (byte)digits[-i]; 160 161 if (negative) { 162 buf[--charPos] = '-'; 163 } 164 165 return StringLatin1.newString(buf, charPos, (33 - charPos)); 166 } 167 return toStringUTF16(i, radix); 168 } 169 170 private static String toStringUTF16(int i, int radix) { 171 byte[] buf = new byte[33 * 2]; 172 boolean negative = (i < 0); 173 int charPos = 32; 174 if (!negative) { 175 i = -i; 176 } 177 while (i <= -radix) { 178 StringUTF16.putChar(buf, charPos--, digits[-(i % radix)]); 179 i = i / radix; 180 } 181 StringUTF16.putChar(buf, charPos, digits[-i]); 182 183 if (negative) { 184 StringUTF16.putChar(buf, --charPos, '-'); 185 } 186 return StringUTF16.newString(buf, charPos, (33 - charPos)); 187 } 188 189 /** 190 * Returns a string representation of the first argument as an 191 * unsigned integer value in the radix specified by the second 192 * argument. 193 * 194 * <p>If the radix is smaller than {@code Character.MIN_RADIX} 195 * or larger than {@code Character.MAX_RADIX}, then the radix 196 * {@code 10} is used instead. 197 * 198 * <p>Note that since the first argument is treated as an unsigned 199 * value, no leading sign character is printed. 200 * 201 * <p>If the magnitude is zero, it is represented by a single zero 202 * character {@code '0'} ({@code '\u005Cu0030'}); otherwise, 203 * the first character of the representation of the magnitude will 204 * not be the zero character. 205 * 206 * <p>The behavior of radixes and the characters used as digits 207 * are the same as {@link #toString(int, int) toString}. 208 * 209 * @param i an integer to be converted to an unsigned string. 210 * @param radix the radix to use in the string representation. 211 * @return an unsigned string representation of the argument in the specified radix. 212 * @see #toString(int, int) 213 * @since 1.8 214 */ 215 public static String toUnsignedString(int i, int radix) { 216 return Long.toUnsignedString(toUnsignedLong(i), radix); 217 } 218 219 /** 220 * Returns a string representation of the integer argument as an 221 * unsigned integer in base 16. 222 * 223 * <p>The unsigned integer value is the argument plus 2<sup>32</sup> 224 * if the argument is negative; otherwise, it is equal to the 225 * argument. This value is converted to a string of ASCII digits 226 * in hexadecimal (base 16) with no extra leading 227 * {@code 0}s. 228 * 229 * <p>The value of the argument can be recovered from the returned 230 * string {@code s} by calling {@link 231 * Integer#parseUnsignedInt(String, int) 232 * Integer.parseUnsignedInt(s, 16)}. 233 * 234 * <p>If the unsigned magnitude is zero, it is represented by a 235 * single zero character {@code '0'} ({@code '\u005Cu0030'}); 236 * otherwise, the first character of the representation of the 237 * unsigned magnitude will not be the zero character. The 238 * following characters are used as hexadecimal digits: 239 * 240 * <blockquote> 241 * {@code 0123456789abcdef} 242 * </blockquote> 243 * 244 * These are the characters {@code '\u005Cu0030'} through 245 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through 246 * {@code '\u005Cu0066'}. If uppercase letters are 247 * desired, the {@link java.lang.String#toUpperCase()} method may 248 * be called on the result: 249 * 250 * <blockquote> 251 * {@code Integer.toHexString(n).toUpperCase()} 252 * </blockquote> 253 * 254 * @param i an integer to be converted to a string. 255 * @return the string representation of the unsigned integer value 256 * represented by the argument in hexadecimal (base 16). 257 * @see #parseUnsignedInt(String, int) 258 * @see #toUnsignedString(int, int) 259 * @since 1.0.2 260 */ 261 public static String toHexString(int i) { 262 return toUnsignedString0(i, 4); 263 } 264 265 /** 266 * Returns a string representation of the integer argument as an 267 * unsigned integer in base 8. 268 * 269 * <p>The unsigned integer value is the argument plus 2<sup>32</sup> 270 * if the argument is negative; otherwise, it is equal to the 271 * argument. This value is converted to a string of ASCII digits 272 * in octal (base 8) with no extra leading {@code 0}s. 273 * 274 * <p>The value of the argument can be recovered from the returned 275 * string {@code s} by calling {@link 276 * Integer#parseUnsignedInt(String, int) 277 * Integer.parseUnsignedInt(s, 8)}. 278 * 279 * <p>If the unsigned magnitude is zero, it is represented by a 280 * single zero character {@code '0'} ({@code '\u005Cu0030'}); 281 * otherwise, the first character of the representation of the 282 * unsigned magnitude will not be the zero character. The 283 * following characters are used as octal digits: 284 * 285 * <blockquote> 286 * {@code 01234567} 287 * </blockquote> 288 * 289 * These are the characters {@code '\u005Cu0030'} through 290 * {@code '\u005Cu0037'}. 291 * 292 * @param i an integer to be converted to a string. 293 * @return the string representation of the unsigned integer value 294 * represented by the argument in octal (base 8). 295 * @see #parseUnsignedInt(String, int) 296 * @see #toUnsignedString(int, int) 297 * @since 1.0.2 298 */ 299 public static String toOctalString(int i) { 300 return toUnsignedString0(i, 3); 301 } 302 303 /** 304 * Returns a string representation of the integer argument as an 305 * unsigned integer in base 2. 306 * 307 * <p>The unsigned integer value is the argument plus 2<sup>32</sup> 308 * if the argument is negative; otherwise it is equal to the 309 * argument. This value is converted to a string of ASCII digits 310 * in binary (base 2) with no extra leading {@code 0}s. 311 * 312 * <p>The value of the argument can be recovered from the returned 313 * string {@code s} by calling {@link 314 * Integer#parseUnsignedInt(String, int) 315 * Integer.parseUnsignedInt(s, 2)}. 316 * 317 * <p>If the unsigned magnitude is zero, it is represented by a 318 * single zero character {@code '0'} ({@code '\u005Cu0030'}); 319 * otherwise, the first character of the representation of the 320 * unsigned magnitude will not be the zero character. The 321 * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code 322 * '1'} ({@code '\u005Cu0031'}) are used as binary digits. 323 * 324 * @param i an integer to be converted to a string. 325 * @return the string representation of the unsigned integer value 326 * represented by the argument in binary (base 2). 327 * @see #parseUnsignedInt(String, int) 328 * @see #toUnsignedString(int, int) 329 * @since 1.0.2 330 */ 331 public static String toBinaryString(int i) { 332 return toUnsignedString0(i, 1); 333 } 334 335 /** 336 * Convert the integer to an unsigned number. 337 */ 338 private static String toUnsignedString0(int val, int shift) { 339 // assert shift > 0 && shift <=5 : "Illegal shift value"; 340 int mag = Integer.SIZE - Integer.numberOfLeadingZeros(val); 341 int chars = Math.max(((mag + (shift - 1)) / shift), 1); 342 if (COMPACT_STRINGS) { 343 byte[] buf = new byte[chars]; 344 formatUnsignedInt(val, shift, buf, 0, chars); 345 return new String(buf, LATIN1); 346 } else { 347 byte[] buf = new byte[chars * 2]; 348 formatUnsignedIntUTF16(val, shift, buf, 0, chars); 349 return new String(buf, UTF16); 350 } 351 } 352 353 /** 354 * Format an {@code int} (treated as unsigned) into a character buffer. If 355 * {@code len} exceeds the formatted ASCII representation of {@code val}, 356 * {@code buf} will be padded with leading zeroes. 357 * 358 * @param val the unsigned int to format 359 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary) 360 * @param buf the character buffer to write to 361 * @param offset the offset in the destination buffer to start at 362 * @param len the number of characters to write 363 */ 364 static void formatUnsignedInt(int val, int shift, char[] buf, int offset, int len) { 365 // assert shift > 0 && shift <=5 : "Illegal shift value"; 366 // assert offset >= 0 && offset < buf.length : "illegal offset"; 367 // assert len > 0 && (offset + len) <= buf.length : "illegal length"; 368 int charPos = offset + len; 369 int radix = 1 << shift; 370 int mask = radix - 1; 371 do { 372 buf[--charPos] = Integer.digits[val & mask]; 373 val >>>= shift; 374 } while (charPos > offset); 375 } 376 377 /** byte[]/LATIN1 version */ 378 static void formatUnsignedInt(int val, int shift, byte[] buf, int offset, int len) { 379 int charPos = offset + len; 380 int radix = 1 << shift; 381 int mask = radix - 1; 382 do { 383 buf[--charPos] = (byte)Integer.digits[val & mask]; 384 val >>>= shift; 385 } while (charPos > offset); 386 } 387 388 /** byte[]/UTF16 version */ 389 private static void formatUnsignedIntUTF16(int val, int shift, byte[] buf, int offset, int len) { 390 int charPos = offset + len; 391 int radix = 1 << shift; 392 int mask = radix - 1; 393 do { 394 StringUTF16.putChar(buf, --charPos, Integer.digits[val & mask]); 395 val >>>= shift; 396 } while (charPos > offset); 397 } 398 399 static final byte[] DigitTens = { 400 '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', 401 '1', '1', '1', '1', '1', '1', '1', '1', '1', '1', 402 '2', '2', '2', '2', '2', '2', '2', '2', '2', '2', 403 '3', '3', '3', '3', '3', '3', '3', '3', '3', '3', 404 '4', '4', '4', '4', '4', '4', '4', '4', '4', '4', 405 '5', '5', '5', '5', '5', '5', '5', '5', '5', '5', 406 '6', '6', '6', '6', '6', '6', '6', '6', '6', '6', 407 '7', '7', '7', '7', '7', '7', '7', '7', '7', '7', 408 '8', '8', '8', '8', '8', '8', '8', '8', '8', '8', 409 '9', '9', '9', '9', '9', '9', '9', '9', '9', '9', 410 } ; 411 412 static final byte[] DigitOnes = { 413 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 414 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 415 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 416 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 417 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 418 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 419 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 420 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 421 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 422 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 423 } ; 424 425 426 /** 427 * Returns a {@code String} object representing the 428 * specified integer. The argument is converted to signed decimal 429 * representation and returned as a string, exactly as if the 430 * argument and radix 10 were given as arguments to the {@link 431 * #toString(int, int)} method. 432 * 433 * @param i an integer to be converted. 434 * @return a string representation of the argument in base 10. 435 */ 436 @HotSpotIntrinsicCandidate 437 public static String toString(int i) { 438 int size = stringSize(i); 439 if (COMPACT_STRINGS) { 440 byte[] buf = new byte[size]; 441 getChars(i, size, buf); 442 return new String(buf, LATIN1); 443 } else { 444 byte[] buf = new byte[size * 2]; 445 StringUTF16.getChars(i, size, buf); 446 return new String(buf, UTF16); 447 } 448 } 449 450 /** 451 * Returns a string representation of the argument as an unsigned 452 * decimal value. 453 * 454 * The argument is converted to unsigned decimal representation 455 * and returned as a string exactly as if the argument and radix 456 * 10 were given as arguments to the {@link #toUnsignedString(int, 457 * int)} method. 458 * 459 * @param i an integer to be converted to an unsigned string. 460 * @return an unsigned string representation of the argument. 461 * @see #toUnsignedString(int, int) 462 * @since 1.8 463 */ 464 public static String toUnsignedString(int i) { 465 return Long.toString(toUnsignedLong(i)); 466 } 467 468 /** 469 * Places characters representing the integer i into the 470 * character array buf. The characters are placed into 471 * the buffer backwards starting with the least significant 472 * digit at the specified index (exclusive), and working 473 * backwards from there. 474 * 475 * @implNote This method converts positive inputs into negative 476 * values, to cover the Integer.MIN_VALUE case. Converting otherwise 477 * (negative to positive) will expose -Integer.MIN_VALUE that overflows 478 * integer. 479 * 480 * @param i value to convert 481 * @param index next index, after the least significant digit 482 * @param buf target buffer, Latin1-encoded 483 * @return index of the most significant digit or minus sign, if present 484 */ 485 static int getChars(int i, int index, byte[] buf) { 486 int q, r; 487 int charPos = index; 488 489 boolean negative = i < 0; 490 if (!negative) { 491 i = -i; 492 } 493 494 // Generate two digits per iteration 495 while (i <= -100) { 496 q = i / 100; 497 r = (q * 100) - i; 498 i = q; 499 buf[--charPos] = DigitOnes[r]; 500 buf[--charPos] = DigitTens[r]; 501 } 502 503 // We know there are at most two digits left at this point. 504 q = i / 10; 505 r = (q * 10) - i; 506 buf[--charPos] = (byte)('0' + r); 507 508 // Whatever left is the remaining digit. 509 if (q < 0) { 510 buf[--charPos] = (byte)('0' - q); 511 } 512 513 if (negative) { 514 buf[--charPos] = (byte)'-'; 515 } 516 return charPos; 517 } 518 519 // Left here for compatibility reasons, see JDK-8143900. 520 static final int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999, 521 99999999, 999999999, Integer.MAX_VALUE }; 522 523 /** 524 * Returns the string representation size for a given int value. 525 * 526 * @param x int value 527 * @return string size 528 * 529 * @implNote There are other ways to compute this: e.g. binary search, 530 * but values are biased heavily towards zero, and therefore linear search 531 * wins. The iteration results are also routinely inlined in the generated 532 * code after loop unrolling. 533 */ 534 static int stringSize(int x) { 535 int d = 1; 536 if (x >= 0) { 537 d = 0; 538 x = -x; 539 } 540 int p = -10; 541 for (int i = 1; i < 10; i++) { 542 if (x > p) 543 return i + d; 544 p = 10 * p; 545 } 546 return 10 + d; 547 } 548 549 /** 550 * Parses the string argument as a signed integer in the radix 551 * specified by the second argument. The characters in the string 552 * must all be digits of the specified radix (as determined by 553 * whether {@link java.lang.Character#digit(char, int)} returns a 554 * nonnegative value), except that the first character may be an 555 * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to 556 * indicate a negative value or an ASCII plus sign {@code '+'} 557 * ({@code '\u005Cu002B'}) to indicate a positive value. The 558 * resulting integer value is returned. 559 * 560 * <p>An exception of type {@code NumberFormatException} is 561 * thrown if any of the following situations occurs: 562 * <ul> 563 * <li>The first argument is {@code null} or is a string of 564 * length zero. 565 * 566 * <li>The radix is either smaller than 567 * {@link java.lang.Character#MIN_RADIX} or 568 * larger than {@link java.lang.Character#MAX_RADIX}. 569 * 570 * <li>Any character of the string is not a digit of the specified 571 * radix, except that the first character may be a minus sign 572 * {@code '-'} ({@code '\u005Cu002D'}) or plus sign 573 * {@code '+'} ({@code '\u005Cu002B'}) provided that the 574 * string is longer than length 1. 575 * 576 * <li>The value represented by the string is not a value of type 577 * {@code int}. 578 * </ul> 579 * 580 * <p>Examples: 581 * <blockquote><pre> 582 * parseInt("0", 10) returns 0 583 * parseInt("473", 10) returns 473 584 * parseInt("+42", 10) returns 42 585 * parseInt("-0", 10) returns 0 586 * parseInt("-FF", 16) returns -255 587 * parseInt("1100110", 2) returns 102 588 * parseInt("2147483647", 10) returns 2147483647 589 * parseInt("-2147483648", 10) returns -2147483648 590 * parseInt("2147483648", 10) throws a NumberFormatException 591 * parseInt("99", 8) throws a NumberFormatException 592 * parseInt("Kona", 10) throws a NumberFormatException 593 * parseInt("Kona", 27) returns 411787 594 * </pre></blockquote> 595 * 596 * @param s the {@code String} containing the integer 597 * representation to be parsed 598 * @param radix the radix to be used while parsing {@code s}. 599 * @return the integer represented by the string argument in the 600 * specified radix. 601 * @exception NumberFormatException if the {@code String} 602 * does not contain a parsable {@code int}. 603 */ 604 public static int parseInt(String s, int radix) 605 throws NumberFormatException 606 { 607 /* 608 * WARNING: This method may be invoked early during VM initialization 609 * before IntegerCache is initialized. Care must be taken to not use 610 * the valueOf method. 611 */ 612 613 if (s == null) { 614 throw new NumberFormatException("null"); 615 } 616 617 if (radix < Character.MIN_RADIX) { 618 throw new NumberFormatException("radix " + radix + 619 " less than Character.MIN_RADIX"); 620 } 621 622 if (radix > Character.MAX_RADIX) { 623 throw new NumberFormatException("radix " + radix + 624 " greater than Character.MAX_RADIX"); 625 } 626 627 boolean negative = false; 628 int i = 0, len = s.length(); 629 int limit = -Integer.MAX_VALUE; 630 631 if (len > 0) { 632 char firstChar = s.charAt(0); 633 if (firstChar < '0') { // Possible leading "+" or "-" 634 if (firstChar == '-') { 635 negative = true; 636 limit = Integer.MIN_VALUE; 637 } else if (firstChar != '+') { 638 throw NumberFormatException.forInputString(s); 639 } 640 641 if (len == 1) { // Cannot have lone "+" or "-" 642 throw NumberFormatException.forInputString(s); 643 } 644 i++; 645 } 646 int multmin = limit / radix; 647 int result = 0; 648 while (i < len) { 649 // Accumulating negatively avoids surprises near MAX_VALUE 650 int digit = Character.digit(s.charAt(i++), radix); 651 if (digit < 0 || result < multmin) { 652 throw NumberFormatException.forInputString(s); 653 } 654 result *= radix; 655 if (result < limit + digit) { 656 throw NumberFormatException.forInputString(s); 657 } 658 result -= digit; 659 } 660 return negative ? result : -result; 661 } else { 662 throw NumberFormatException.forInputString(s); 663 } 664 } 665 666 /** 667 * Parses the {@link CharSequence} argument as a signed {@code int} in the 668 * specified {@code radix}, beginning at the specified {@code beginIndex} 669 * and extending to {@code endIndex - 1}. 670 * 671 * <p>The method does not take steps to guard against the 672 * {@code CharSequence} being mutated while parsing. 673 * 674 * @param s the {@code CharSequence} containing the {@code int} 675 * representation to be parsed 676 * @param beginIndex the beginning index, inclusive. 677 * @param endIndex the ending index, exclusive. 678 * @param radix the radix to be used while parsing {@code s}. 679 * @return the signed {@code int} represented by the subsequence in 680 * the specified radix. 681 * @throws NullPointerException if {@code s} is null. 682 * @throws IndexOutOfBoundsException if {@code beginIndex} is 683 * negative, or if {@code beginIndex} is greater than 684 * {@code endIndex} or if {@code endIndex} is greater than 685 * {@code s.length()}. 686 * @throws NumberFormatException if the {@code CharSequence} does not 687 * contain a parsable {@code int} in the specified 688 * {@code radix}, or if {@code radix} is either smaller than 689 * {@link java.lang.Character#MIN_RADIX} or larger than 690 * {@link java.lang.Character#MAX_RADIX}. 691 * @since 9 692 */ 693 public static int parseInt(CharSequence s, int beginIndex, int endIndex, int radix) 694 throws NumberFormatException { 695 s = Objects.requireNonNull(s); 696 697 if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) { 698 throw new IndexOutOfBoundsException(); 699 } 700 if (radix < Character.MIN_RADIX) { 701 throw new NumberFormatException("radix " + radix + 702 " less than Character.MIN_RADIX"); 703 } 704 if (radix > Character.MAX_RADIX) { 705 throw new NumberFormatException("radix " + radix + 706 " greater than Character.MAX_RADIX"); 707 } 708 709 boolean negative = false; 710 int i = beginIndex; 711 int limit = -Integer.MAX_VALUE; 712 713 if (i < endIndex) { 714 char firstChar = s.charAt(i); 715 if (firstChar < '0') { // Possible leading "+" or "-" 716 if (firstChar == '-') { 717 negative = true; 718 limit = Integer.MIN_VALUE; 719 } else if (firstChar != '+') { 720 throw NumberFormatException.forCharSequence(s, beginIndex, 721 endIndex, i); 722 } 723 i++; 724 if (i == endIndex) { // Cannot have lone "+" or "-" 725 throw NumberFormatException.forCharSequence(s, beginIndex, 726 endIndex, i); 727 } 728 } 729 int multmin = limit / radix; 730 int result = 0; 731 while (i < endIndex) { 732 // Accumulating negatively avoids surprises near MAX_VALUE 733 int digit = Character.digit(s.charAt(i), radix); 734 if (digit < 0 || result < multmin) { 735 throw NumberFormatException.forCharSequence(s, beginIndex, 736 endIndex, i); 737 } 738 result *= radix; 739 if (result < limit + digit) { 740 throw NumberFormatException.forCharSequence(s, beginIndex, 741 endIndex, i); 742 } 743 i++; 744 result -= digit; 745 } 746 return negative ? result : -result; 747 } else { 748 throw NumberFormatException.forInputString(""); 749 } 750 } 751 752 /** 753 * Parses the string argument as a signed decimal integer. The 754 * characters in the string must all be decimal digits, except 755 * that the first character may be an ASCII minus sign {@code '-'} 756 * ({@code '\u005Cu002D'}) to indicate a negative value or an 757 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to 758 * indicate a positive value. The resulting integer value is 759 * returned, exactly as if the argument and the radix 10 were 760 * given as arguments to the {@link #parseInt(java.lang.String, 761 * int)} method. 762 * 763 * @param s a {@code String} containing the {@code int} 764 * representation to be parsed 765 * @return the integer value represented by the argument in decimal. 766 * @exception NumberFormatException if the string does not contain a 767 * parsable integer. 768 */ 769 public static int parseInt(String s) throws NumberFormatException { 770 return parseInt(s,10); 771 } 772 773 /** 774 * Parses the string argument as an unsigned integer in the radix 775 * specified by the second argument. An unsigned integer maps the 776 * values usually associated with negative numbers to positive 777 * numbers larger than {@code MAX_VALUE}. 778 * 779 * The characters in the string must all be digits of the 780 * specified radix (as determined by whether {@link 781 * java.lang.Character#digit(char, int)} returns a nonnegative 782 * value), except that the first character may be an ASCII plus 783 * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting 784 * integer value is returned. 785 * 786 * <p>An exception of type {@code NumberFormatException} is 787 * thrown if any of the following situations occurs: 788 * <ul> 789 * <li>The first argument is {@code null} or is a string of 790 * length zero. 791 * 792 * <li>The radix is either smaller than 793 * {@link java.lang.Character#MIN_RADIX} or 794 * larger than {@link java.lang.Character#MAX_RADIX}. 795 * 796 * <li>Any character of the string is not a digit of the specified 797 * radix, except that the first character may be a plus sign 798 * {@code '+'} ({@code '\u005Cu002B'}) provided that the 799 * string is longer than length 1. 800 * 801 * <li>The value represented by the string is larger than the 802 * largest unsigned {@code int}, 2<sup>32</sup>-1. 803 * 804 * </ul> 805 * 806 * 807 * @param s the {@code String} containing the unsigned integer 808 * representation to be parsed 809 * @param radix the radix to be used while parsing {@code s}. 810 * @return the integer represented by the string argument in the 811 * specified radix. 812 * @throws NumberFormatException if the {@code String} 813 * does not contain a parsable {@code int}. 814 * @since 1.8 815 */ 816 public static int parseUnsignedInt(String s, int radix) 817 throws NumberFormatException { 818 if (s == null) { 819 throw new NumberFormatException("null"); 820 } 821 822 int len = s.length(); 823 if (len > 0) { 824 char firstChar = s.charAt(0); 825 if (firstChar == '-') { 826 throw new 827 NumberFormatException(String.format("Illegal leading minus sign " + 828 "on unsigned string %s.", s)); 829 } else { 830 if (len <= 5 || // Integer.MAX_VALUE in Character.MAX_RADIX is 6 digits 831 (radix == 10 && len <= 9) ) { // Integer.MAX_VALUE in base 10 is 10 digits 832 return parseInt(s, radix); 833 } else { 834 long ell = Long.parseLong(s, radix); 835 if ((ell & 0xffff_ffff_0000_0000L) == 0) { 836 return (int) ell; 837 } else { 838 throw new 839 NumberFormatException(String.format("String value %s exceeds " + 840 "range of unsigned int.", s)); 841 } 842 } 843 } 844 } else { 845 throw NumberFormatException.forInputString(s); 846 } 847 } 848 849 /** 850 * Parses the {@link CharSequence} argument as an unsigned {@code int} in 851 * the specified {@code radix}, beginning at the specified 852 * {@code beginIndex} and extending to {@code endIndex - 1}. 853 * 854 * <p>The method does not take steps to guard against the 855 * {@code CharSequence} being mutated while parsing. 856 * 857 * @param s the {@code CharSequence} containing the unsigned 858 * {@code int} representation to be parsed 859 * @param beginIndex the beginning index, inclusive. 860 * @param endIndex the ending index, exclusive. 861 * @param radix the radix to be used while parsing {@code s}. 862 * @return the unsigned {@code int} represented by the subsequence in 863 * the specified radix. 864 * @throws NullPointerException if {@code s} is null. 865 * @throws IndexOutOfBoundsException if {@code beginIndex} is 866 * negative, or if {@code beginIndex} is greater than 867 * {@code endIndex} or if {@code endIndex} is greater than 868 * {@code s.length()}. 869 * @throws NumberFormatException if the {@code CharSequence} does not 870 * contain a parsable unsigned {@code int} in the specified 871 * {@code radix}, or if {@code radix} is either smaller than 872 * {@link java.lang.Character#MIN_RADIX} or larger than 873 * {@link java.lang.Character#MAX_RADIX}. 874 * @since 9 875 */ 876 public static int parseUnsignedInt(CharSequence s, int beginIndex, int endIndex, int radix) 877 throws NumberFormatException { 878 s = Objects.requireNonNull(s); 879 880 if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) { 881 throw new IndexOutOfBoundsException(); 882 } 883 int start = beginIndex, len = endIndex - beginIndex; 884 885 if (len > 0) { 886 char firstChar = s.charAt(start); 887 if (firstChar == '-') { 888 throw new 889 NumberFormatException(String.format("Illegal leading minus sign " + 890 "on unsigned string %s.", s)); 891 } else { 892 if (len <= 5 || // Integer.MAX_VALUE in Character.MAX_RADIX is 6 digits 893 (radix == 10 && len <= 9)) { // Integer.MAX_VALUE in base 10 is 10 digits 894 return parseInt(s, start, start + len, radix); 895 } else { 896 long ell = Long.parseLong(s, start, start + len, radix); 897 if ((ell & 0xffff_ffff_0000_0000L) == 0) { 898 return (int) ell; 899 } else { 900 throw new 901 NumberFormatException(String.format("String value %s exceeds " + 902 "range of unsigned int.", s)); 903 } 904 } 905 } 906 } else { 907 throw new NumberFormatException(""); 908 } 909 } 910 911 /** 912 * Parses the string argument as an unsigned decimal integer. The 913 * characters in the string must all be decimal digits, except 914 * that the first character may be an ASCII plus sign {@code 915 * '+'} ({@code '\u005Cu002B'}). The resulting integer value 916 * is returned, exactly as if the argument and the radix 10 were 917 * given as arguments to the {@link 918 * #parseUnsignedInt(java.lang.String, int)} method. 919 * 920 * @param s a {@code String} containing the unsigned {@code int} 921 * representation to be parsed 922 * @return the unsigned integer value represented by the argument in decimal. 923 * @throws NumberFormatException if the string does not contain a 924 * parsable unsigned integer. 925 * @since 1.8 926 */ 927 public static int parseUnsignedInt(String s) throws NumberFormatException { 928 return parseUnsignedInt(s, 10); 929 } 930 931 /** 932 * Returns an {@code Integer} object holding the value 933 * extracted from the specified {@code String} when parsed 934 * with the radix given by the second argument. The first argument 935 * is interpreted as representing a signed integer in the radix 936 * specified by the second argument, exactly as if the arguments 937 * were given to the {@link #parseInt(java.lang.String, int)} 938 * method. The result is an {@code Integer} object that 939 * represents the integer value specified by the string. 940 * 941 * <p>In other words, this method returns an {@code Integer} 942 * object equal to the value of: 943 * 944 * <blockquote> 945 * {@code new Integer(Integer.parseInt(s, radix))} 946 * </blockquote> 947 * 948 * @param s the string to be parsed. 949 * @param radix the radix to be used in interpreting {@code s} 950 * @return an {@code Integer} object holding the value 951 * represented by the string argument in the specified 952 * radix. 953 * @exception NumberFormatException if the {@code String} 954 * does not contain a parsable {@code int}. 955 */ 956 public static Integer valueOf(String s, int radix) throws NumberFormatException { 957 return Integer.valueOf(parseInt(s,radix)); 958 } 959 960 /** 961 * Returns an {@code Integer} object holding the 962 * value of the specified {@code String}. The argument is 963 * interpreted as representing a signed decimal integer, exactly 964 * as if the argument were given to the {@link 965 * #parseInt(java.lang.String)} method. The result is an 966 * {@code Integer} object that represents the integer value 967 * specified by the string. 968 * 969 * <p>In other words, this method returns an {@code Integer} 970 * object equal to the value of: 971 * 972 * <blockquote> 973 * {@code new Integer(Integer.parseInt(s))} 974 * </blockquote> 975 * 976 * @param s the string to be parsed. 977 * @return an {@code Integer} object holding the value 978 * represented by the string argument. 979 * @exception NumberFormatException if the string cannot be parsed 980 * as an integer. 981 */ 982 public static Integer valueOf(String s) throws NumberFormatException { 983 return Integer.valueOf(parseInt(s, 10)); 984 } 985 986 /** 987 * Cache to support the object identity semantics of autoboxing for values between 988 * -128 and 127 (inclusive) as required by JLS. 989 * 990 * The cache is initialized on first usage. The size of the cache 991 * may be controlled by the {@code -XX:AutoBoxCacheMax=<size>} option. 992 * During VM initialization, java.lang.Integer.IntegerCache.high property 993 * may be set and saved in the private system properties in the 994 * jdk.internal.misc.VM class. 995 */ 996 997 private static class IntegerCache { 998 static final int low = -128; 999 static final int high; 1000 static final Integer cache[]; 1001 1002 static { 1003 // high value may be configured by property 1004 int h = 127; 1005 String integerCacheHighPropValue = 1006 VM.getSavedProperty("java.lang.Integer.IntegerCache.high"); 1007 if (integerCacheHighPropValue != null) { 1008 try { 1009 int i = parseInt(integerCacheHighPropValue); 1010 i = Math.max(i, 127); 1011 // Maximum array size is Integer.MAX_VALUE 1012 h = Math.min(i, Integer.MAX_VALUE - (-low) -1); 1013 } catch( NumberFormatException nfe) { 1014 // If the property cannot be parsed into an int, ignore it. 1015 } 1016 } 1017 high = h; 1018 1019 cache = new Integer[(high - low) + 1]; 1020 int j = low; 1021 for(int k = 0; k < cache.length; k++) 1022 cache[k] = new Integer(j++); 1023 1024 // range [-128, 127] must be interned (JLS7 5.1.7) 1025 assert IntegerCache.high >= 127; 1026 } 1027 1028 private IntegerCache() {} 1029 } 1030 1031 /** 1032 * Returns an {@code Integer} instance representing the specified 1033 * {@code int} value. If a new {@code Integer} instance is not 1034 * required, this method should generally be used in preference to 1035 * the constructor {@link #Integer(int)}, as this method is likely 1036 * to yield significantly better space and time performance by 1037 * caching frequently requested values. 1038 * 1039 * This method will always cache values in the range -128 to 127, 1040 * inclusive, and may cache other values outside of this range. 1041 * 1042 * @param i an {@code int} value. 1043 * @return an {@code Integer} instance representing {@code i}. 1044 * @since 1.5 1045 */ 1046 @HotSpotIntrinsicCandidate 1047 public static Integer valueOf(int i) { 1048 if (i >= IntegerCache.low && i <= IntegerCache.high) 1049 return IntegerCache.cache[i + (-IntegerCache.low)]; 1050 return new Integer(i); 1051 } 1052 1053 /** 1054 * The value of the {@code Integer}. 1055 * 1056 * @serial 1057 */ 1058 private final int value; 1059 1060 /** 1061 * Constructs a newly allocated {@code Integer} object that 1062 * represents the specified {@code int} value. 1063 * 1064 * @param value the value to be represented by the 1065 * {@code Integer} object. 1066 * 1067 * @deprecated 1068 * It is rarely appropriate to use this constructor. The static factory 1069 * {@link #valueOf(int)} is generally a better choice, as it is 1070 * likely to yield significantly better space and time performance. 1071 */ 1072 @Deprecated(since="9") 1073 public Integer(int value) { 1074 this.value = value; 1075 } 1076 1077 /** 1078 * Constructs a newly allocated {@code Integer} object that 1079 * represents the {@code int} value indicated by the 1080 * {@code String} parameter. The string is converted to an 1081 * {@code int} value in exactly the manner used by the 1082 * {@code parseInt} method for radix 10. 1083 * 1084 * @param s the {@code String} to be converted to an {@code Integer}. 1085 * @throws NumberFormatException if the {@code String} does not 1086 * contain a parsable integer. 1087 * 1088 * @deprecated 1089 * It is rarely appropriate to use this constructor. 1090 * Use {@link #parseInt(String)} to convert a string to a 1091 * {@code int} primitive, or use {@link #valueOf(String)} 1092 * to convert a string to an {@code Integer} object. 1093 */ 1094 @Deprecated(since="9") 1095 public Integer(String s) throws NumberFormatException { 1096 this.value = parseInt(s, 10); 1097 } 1098 1099 /** 1100 * Returns the value of this {@code Integer} as a {@code byte} 1101 * after a narrowing primitive conversion. 1102 * @jls 5.1.3 Narrowing Primitive Conversions 1103 */ 1104 public byte byteValue() { 1105 return (byte)value; 1106 } 1107 1108 /** 1109 * Returns the value of this {@code Integer} as a {@code short} 1110 * after a narrowing primitive conversion. 1111 * @jls 5.1.3 Narrowing Primitive Conversions 1112 */ 1113 public short shortValue() { 1114 return (short)value; 1115 } 1116 1117 /** 1118 * Returns the value of this {@code Integer} as an 1119 * {@code int}. 1120 */ 1121 @HotSpotIntrinsicCandidate 1122 public int intValue() { 1123 return value; 1124 } 1125 1126 /** 1127 * Returns the value of this {@code Integer} as a {@code long} 1128 * after a widening primitive conversion. 1129 * @jls 5.1.2 Widening Primitive Conversions 1130 * @see Integer#toUnsignedLong(int) 1131 */ 1132 public long longValue() { 1133 return (long)value; 1134 } 1135 1136 /** 1137 * Returns the value of this {@code Integer} as a {@code float} 1138 * after a widening primitive conversion. 1139 * @jls 5.1.2 Widening Primitive Conversions 1140 */ 1141 public float floatValue() { 1142 return (float)value; 1143 } 1144 1145 /** 1146 * Returns the value of this {@code Integer} as a {@code double} 1147 * after a widening primitive conversion. 1148 * @jls 5.1.2 Widening Primitive Conversions 1149 */ 1150 public double doubleValue() { 1151 return (double)value; 1152 } 1153 1154 /** 1155 * Returns a {@code String} object representing this 1156 * {@code Integer}'s value. The value is converted to signed 1157 * decimal representation and returned as a string, exactly as if 1158 * the integer value were given as an argument to the {@link 1159 * java.lang.Integer#toString(int)} method. 1160 * 1161 * @return a string representation of the value of this object in 1162 * base 10. 1163 */ 1164 public String toString() { 1165 return toString(value); 1166 } 1167 1168 /** 1169 * Returns a hash code for this {@code Integer}. 1170 * 1171 * @return a hash code value for this object, equal to the 1172 * primitive {@code int} value represented by this 1173 * {@code Integer} object. 1174 */ 1175 @Override 1176 public int hashCode() { 1177 return Integer.hashCode(value); 1178 } 1179 1180 /** 1181 * Returns a hash code for an {@code int} value; compatible with 1182 * {@code Integer.hashCode()}. 1183 * 1184 * @param value the value to hash 1185 * @since 1.8 1186 * 1187 * @return a hash code value for an {@code int} value. 1188 */ 1189 public static int hashCode(int value) { 1190 return value; 1191 } 1192 1193 /** 1194 * Compares this object to the specified object. The result is 1195 * {@code true} if and only if the argument is not 1196 * {@code null} and is an {@code Integer} object that 1197 * contains the same {@code int} value as this object. 1198 * 1199 * @param obj the object to compare with. 1200 * @return {@code true} if the objects are the same; 1201 * {@code false} otherwise. 1202 */ 1203 public boolean equals(Object obj) { 1204 if (obj instanceof Integer) { 1205 return value == ((Integer)obj).intValue(); 1206 } 1207 return false; 1208 } 1209 1210 /** 1211 * Determines the integer value of the system property with the 1212 * specified name. 1213 * 1214 * <p>The first argument is treated as the name of a system 1215 * property. System properties are accessible through the {@link 1216 * java.lang.System#getProperty(java.lang.String)} method. The 1217 * string value of this property is then interpreted as an integer 1218 * value using the grammar supported by {@link Integer#decode decode} and 1219 * an {@code Integer} object representing this value is returned. 1220 * 1221 * <p>If there is no property with the specified name, if the 1222 * specified name is empty or {@code null}, or if the property 1223 * does not have the correct numeric format, then {@code null} is 1224 * returned. 1225 * 1226 * <p>In other words, this method returns an {@code Integer} 1227 * object equal to the value of: 1228 * 1229 * <blockquote> 1230 * {@code getInteger(nm, null)} 1231 * </blockquote> 1232 * 1233 * @param nm property name. 1234 * @return the {@code Integer} value of the property. 1235 * @throws SecurityException for the same reasons as 1236 * {@link System#getProperty(String) System.getProperty} 1237 * @see java.lang.System#getProperty(java.lang.String) 1238 * @see java.lang.System#getProperty(java.lang.String, java.lang.String) 1239 */ 1240 public static Integer getInteger(String nm) { 1241 return getInteger(nm, null); 1242 } 1243 1244 /** 1245 * Determines the integer value of the system property with the 1246 * specified name. 1247 * 1248 * <p>The first argument is treated as the name of a system 1249 * property. System properties are accessible through the {@link 1250 * java.lang.System#getProperty(java.lang.String)} method. The 1251 * string value of this property is then interpreted as an integer 1252 * value using the grammar supported by {@link Integer#decode decode} and 1253 * an {@code Integer} object representing this value is returned. 1254 * 1255 * <p>The second argument is the default value. An {@code Integer} object 1256 * that represents the value of the second argument is returned if there 1257 * is no property of the specified name, if the property does not have 1258 * the correct numeric format, or if the specified name is empty or 1259 * {@code null}. 1260 * 1261 * <p>In other words, this method returns an {@code Integer} object 1262 * equal to the value of: 1263 * 1264 * <blockquote> 1265 * {@code getInteger(nm, new Integer(val))} 1266 * </blockquote> 1267 * 1268 * but in practice it may be implemented in a manner such as: 1269 * 1270 * <blockquote><pre> 1271 * Integer result = getInteger(nm, null); 1272 * return (result == null) ? new Integer(val) : result; 1273 * </pre></blockquote> 1274 * 1275 * to avoid the unnecessary allocation of an {@code Integer} 1276 * object when the default value is not needed. 1277 * 1278 * @param nm property name. 1279 * @param val default value. 1280 * @return the {@code Integer} value of the property. 1281 * @throws SecurityException for the same reasons as 1282 * {@link System#getProperty(String) System.getProperty} 1283 * @see java.lang.System#getProperty(java.lang.String) 1284 * @see java.lang.System#getProperty(java.lang.String, java.lang.String) 1285 */ 1286 public static Integer getInteger(String nm, int val) { 1287 Integer result = getInteger(nm, null); 1288 return (result == null) ? Integer.valueOf(val) : result; 1289 } 1290 1291 /** 1292 * Returns the integer value of the system property with the 1293 * specified name. The first argument is treated as the name of a 1294 * system property. System properties are accessible through the 1295 * {@link java.lang.System#getProperty(java.lang.String)} method. 1296 * The string value of this property is then interpreted as an 1297 * integer value, as per the {@link Integer#decode decode} method, 1298 * and an {@code Integer} object representing this value is 1299 * returned; in summary: 1300 * 1301 * <ul><li>If the property value begins with the two ASCII characters 1302 * {@code 0x} or the ASCII character {@code #}, not 1303 * followed by a minus sign, then the rest of it is parsed as a 1304 * hexadecimal integer exactly as by the method 1305 * {@link #valueOf(java.lang.String, int)} with radix 16. 1306 * <li>If the property value begins with the ASCII character 1307 * {@code 0} followed by another character, it is parsed as an 1308 * octal integer exactly as by the method 1309 * {@link #valueOf(java.lang.String, int)} with radix 8. 1310 * <li>Otherwise, the property value is parsed as a decimal integer 1311 * exactly as by the method {@link #valueOf(java.lang.String, int)} 1312 * with radix 10. 1313 * </ul> 1314 * 1315 * <p>The second argument is the default value. The default value is 1316 * returned if there is no property of the specified name, if the 1317 * property does not have the correct numeric format, or if the 1318 * specified name is empty or {@code null}. 1319 * 1320 * @param nm property name. 1321 * @param val default value. 1322 * @return the {@code Integer} value of the property. 1323 * @throws SecurityException for the same reasons as 1324 * {@link System#getProperty(String) System.getProperty} 1325 * @see System#getProperty(java.lang.String) 1326 * @see System#getProperty(java.lang.String, java.lang.String) 1327 */ 1328 public static Integer getInteger(String nm, Integer val) { 1329 String v = null; 1330 try { 1331 v = System.getProperty(nm); 1332 } catch (IllegalArgumentException | NullPointerException e) { 1333 } 1334 if (v != null) { 1335 try { 1336 return Integer.decode(v); 1337 } catch (NumberFormatException e) { 1338 } 1339 } 1340 return val; 1341 } 1342 1343 /** 1344 * Decodes a {@code String} into an {@code Integer}. 1345 * Accepts decimal, hexadecimal, and octal numbers given 1346 * by the following grammar: 1347 * 1348 * <blockquote> 1349 * <dl> 1350 * <dt><i>DecodableString:</i> 1351 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i> 1352 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i> 1353 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i> 1354 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i> 1355 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i> 1356 * 1357 * <dt><i>Sign:</i> 1358 * <dd>{@code -} 1359 * <dd>{@code +} 1360 * </dl> 1361 * </blockquote> 1362 * 1363 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i> 1364 * are as defined in section 3.10.1 of 1365 * <cite>The Java™ Language Specification</cite>, 1366 * except that underscores are not accepted between digits. 1367 * 1368 * <p>The sequence of characters following an optional 1369 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}", 1370 * "{@code #}", or leading zero) is parsed as by the {@code 1371 * Integer.parseInt} method with the indicated radix (10, 16, or 1372 * 8). This sequence of characters must represent a positive 1373 * value or a {@link NumberFormatException} will be thrown. The 1374 * result is negated if first character of the specified {@code 1375 * String} is the minus sign. No whitespace characters are 1376 * permitted in the {@code String}. 1377 * 1378 * @param nm the {@code String} to decode. 1379 * @return an {@code Integer} object holding the {@code int} 1380 * value represented by {@code nm} 1381 * @exception NumberFormatException if the {@code String} does not 1382 * contain a parsable integer. 1383 * @see java.lang.Integer#parseInt(java.lang.String, int) 1384 */ 1385 public static Integer decode(String nm) throws NumberFormatException { 1386 int radix = 10; 1387 int index = 0; 1388 boolean negative = false; 1389 Integer result; 1390 1391 if (nm.length() == 0) 1392 throw new NumberFormatException("Zero length string"); 1393 char firstChar = nm.charAt(0); 1394 // Handle sign, if present 1395 if (firstChar == '-') { 1396 negative = true; 1397 index++; 1398 } else if (firstChar == '+') 1399 index++; 1400 1401 // Handle radix specifier, if present 1402 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) { 1403 index += 2; 1404 radix = 16; 1405 } 1406 else if (nm.startsWith("#", index)) { 1407 index ++; 1408 radix = 16; 1409 } 1410 else if (nm.startsWith("0", index) && nm.length() > 1 + index) { 1411 index ++; 1412 radix = 8; 1413 } 1414 1415 if (nm.startsWith("-", index) || nm.startsWith("+", index)) 1416 throw new NumberFormatException("Sign character in wrong position"); 1417 1418 try { 1419 result = Integer.valueOf(nm.substring(index), radix); 1420 result = negative ? Integer.valueOf(-result.intValue()) : result; 1421 } catch (NumberFormatException e) { 1422 // If number is Integer.MIN_VALUE, we'll end up here. The next line 1423 // handles this case, and causes any genuine format error to be 1424 // rethrown. 1425 String constant = negative ? ("-" + nm.substring(index)) 1426 : nm.substring(index); 1427 result = Integer.valueOf(constant, radix); 1428 } 1429 return result; 1430 } 1431 1432 /** 1433 * Compares two {@code Integer} objects numerically. 1434 * 1435 * @param anotherInteger the {@code Integer} to be compared. 1436 * @return the value {@code 0} if this {@code Integer} is 1437 * equal to the argument {@code Integer}; a value less than 1438 * {@code 0} if this {@code Integer} is numerically less 1439 * than the argument {@code Integer}; and a value greater 1440 * than {@code 0} if this {@code Integer} is numerically 1441 * greater than the argument {@code Integer} (signed 1442 * comparison). 1443 * @since 1.2 1444 */ 1445 public int compareTo(Integer anotherInteger) { 1446 return compare(this.value, anotherInteger.value); 1447 } 1448 1449 /** 1450 * Compares two {@code int} values numerically. 1451 * The value returned is identical to what would be returned by: 1452 * <pre> 1453 * Integer.valueOf(x).compareTo(Integer.valueOf(y)) 1454 * </pre> 1455 * 1456 * @param x the first {@code int} to compare 1457 * @param y the second {@code int} to compare 1458 * @return the value {@code 0} if {@code x == y}; 1459 * a value less than {@code 0} if {@code x < y}; and 1460 * a value greater than {@code 0} if {@code x > y} 1461 * @since 1.7 1462 */ 1463 public static int compare(int x, int y) { 1464 return (x < y) ? -1 : ((x == y) ? 0 : 1); 1465 } 1466 1467 /** 1468 * Compares two {@code int} values numerically treating the values 1469 * as unsigned. 1470 * 1471 * @param x the first {@code int} to compare 1472 * @param y the second {@code int} to compare 1473 * @return the value {@code 0} if {@code x == y}; a value less 1474 * than {@code 0} if {@code x < y} as unsigned values; and 1475 * a value greater than {@code 0} if {@code x > y} as 1476 * unsigned values 1477 * @since 1.8 1478 */ 1479 public static int compareUnsigned(int x, int y) { 1480 return compare(x + MIN_VALUE, y + MIN_VALUE); 1481 } 1482 1483 /** 1484 * Converts the argument to a {@code long} by an unsigned 1485 * conversion. In an unsigned conversion to a {@code long}, the 1486 * high-order 32 bits of the {@code long} are zero and the 1487 * low-order 32 bits are equal to the bits of the integer 1488 * argument. 1489 * 1490 * Consequently, zero and positive {@code int} values are mapped 1491 * to a numerically equal {@code long} value and negative {@code 1492 * int} values are mapped to a {@code long} value equal to the 1493 * input plus 2<sup>32</sup>. 1494 * 1495 * @param x the value to convert to an unsigned {@code long} 1496 * @return the argument converted to {@code long} by an unsigned 1497 * conversion 1498 * @since 1.8 1499 */ 1500 public static long toUnsignedLong(int x) { 1501 return ((long) x) & 0xffffffffL; 1502 } 1503 1504 /** 1505 * Returns the unsigned quotient of dividing the first argument by 1506 * the second where each argument and the result is interpreted as 1507 * an unsigned value. 1508 * 1509 * <p>Note that in two's complement arithmetic, the three other 1510 * basic arithmetic operations of add, subtract, and multiply are 1511 * bit-wise identical if the two operands are regarded as both 1512 * being signed or both being unsigned. Therefore separate {@code 1513 * addUnsigned}, etc. methods are not provided. 1514 * 1515 * @param dividend the value to be divided 1516 * @param divisor the value doing the dividing 1517 * @return the unsigned quotient of the first argument divided by 1518 * the second argument 1519 * @see #remainderUnsigned 1520 * @since 1.8 1521 */ 1522 public static int divideUnsigned(int dividend, int divisor) { 1523 // In lieu of tricky code, for now just use long arithmetic. 1524 return (int)(toUnsignedLong(dividend) / toUnsignedLong(divisor)); 1525 } 1526 1527 /** 1528 * Returns the unsigned remainder from dividing the first argument 1529 * by the second where each argument and the result is interpreted 1530 * as an unsigned value. 1531 * 1532 * @param dividend the value to be divided 1533 * @param divisor the value doing the dividing 1534 * @return the unsigned remainder of the first argument divided by 1535 * the second argument 1536 * @see #divideUnsigned 1537 * @since 1.8 1538 */ 1539 public static int remainderUnsigned(int dividend, int divisor) { 1540 // In lieu of tricky code, for now just use long arithmetic. 1541 return (int)(toUnsignedLong(dividend) % toUnsignedLong(divisor)); 1542 } 1543 1544 1545 // Bit twiddling 1546 1547 /** 1548 * The number of bits used to represent an {@code int} value in two's 1549 * complement binary form. 1550 * 1551 * @since 1.5 1552 */ 1553 @Native public static final int SIZE = 32; 1554 1555 /** 1556 * The number of bytes used to represent an {@code int} value in two's 1557 * complement binary form. 1558 * 1559 * @since 1.8 1560 */ 1561 public static final int BYTES = SIZE / Byte.SIZE; 1562 1563 /** 1564 * Returns an {@code int} value with at most a single one-bit, in the 1565 * position of the highest-order ("leftmost") one-bit in the specified 1566 * {@code int} value. Returns zero if the specified value has no 1567 * one-bits in its two's complement binary representation, that is, if it 1568 * is equal to zero. 1569 * 1570 * @param i the value whose highest one bit is to be computed 1571 * @return an {@code int} value with a single one-bit, in the position 1572 * of the highest-order one-bit in the specified value, or zero if 1573 * the specified value is itself equal to zero. 1574 * @since 1.5 1575 */ 1576 public static int highestOneBit(int i) { 1577 // HD, Figure 3-1 1578 i |= (i >> 1); 1579 i |= (i >> 2); 1580 i |= (i >> 4); 1581 i |= (i >> 8); 1582 i |= (i >> 16); 1583 return i - (i >>> 1); 1584 } 1585 1586 /** 1587 * Returns an {@code int} value with at most a single one-bit, in the 1588 * position of the lowest-order ("rightmost") one-bit in the specified 1589 * {@code int} value. Returns zero if the specified value has no 1590 * one-bits in its two's complement binary representation, that is, if it 1591 * is equal to zero. 1592 * 1593 * @param i the value whose lowest one bit is to be computed 1594 * @return an {@code int} value with a single one-bit, in the position 1595 * of the lowest-order one-bit in the specified value, or zero if 1596 * the specified value is itself equal to zero. 1597 * @since 1.5 1598 */ 1599 public static int lowestOneBit(int i) { 1600 // HD, Section 2-1 1601 return i & -i; 1602 } 1603 1604 /** 1605 * Returns the number of zero bits preceding the highest-order 1606 * ("leftmost") one-bit in the two's complement binary representation 1607 * of the specified {@code int} value. Returns 32 if the 1608 * specified value has no one-bits in its two's complement representation, 1609 * in other words if it is equal to zero. 1610 * 1611 * <p>Note that this method is closely related to the logarithm base 2. 1612 * For all positive {@code int} values x: 1613 * <ul> 1614 * <li>floor(log<sub>2</sub>(x)) = {@code 31 - numberOfLeadingZeros(x)} 1615 * <li>ceil(log<sub>2</sub>(x)) = {@code 32 - numberOfLeadingZeros(x - 1)} 1616 * </ul> 1617 * 1618 * @param i the value whose number of leading zeros is to be computed 1619 * @return the number of zero bits preceding the highest-order 1620 * ("leftmost") one-bit in the two's complement binary representation 1621 * of the specified {@code int} value, or 32 if the value 1622 * is equal to zero. 1623 * @since 1.5 1624 */ 1625 @HotSpotIntrinsicCandidate 1626 public static int numberOfLeadingZeros(int i) { 1627 // HD, Figure 5-6 1628 if (i == 0) 1629 return 32; 1630 int n = 1; 1631 if (i >>> 16 == 0) { n += 16; i <<= 16; } 1632 if (i >>> 24 == 0) { n += 8; i <<= 8; } 1633 if (i >>> 28 == 0) { n += 4; i <<= 4; } 1634 if (i >>> 30 == 0) { n += 2; i <<= 2; } 1635 n -= i >>> 31; 1636 return n; 1637 } 1638 1639 /** 1640 * Returns the number of zero bits following the lowest-order ("rightmost") 1641 * one-bit in the two's complement binary representation of the specified 1642 * {@code int} value. Returns 32 if the specified value has no 1643 * one-bits in its two's complement representation, in other words if it is 1644 * equal to zero. 1645 * 1646 * @param i the value whose number of trailing zeros is to be computed 1647 * @return the number of zero bits following the lowest-order ("rightmost") 1648 * one-bit in the two's complement binary representation of the 1649 * specified {@code int} value, or 32 if the value is equal 1650 * to zero. 1651 * @since 1.5 1652 */ 1653 @HotSpotIntrinsicCandidate 1654 public static int numberOfTrailingZeros(int i) { 1655 // HD, Figure 5-14 1656 int y; 1657 if (i == 0) return 32; 1658 int n = 31; 1659 y = i <<16; if (y != 0) { n = n -16; i = y; } 1660 y = i << 8; if (y != 0) { n = n - 8; i = y; } 1661 y = i << 4; if (y != 0) { n = n - 4; i = y; } 1662 y = i << 2; if (y != 0) { n = n - 2; i = y; } 1663 return n - ((i << 1) >>> 31); 1664 } 1665 1666 /** 1667 * Returns the number of one-bits in the two's complement binary 1668 * representation of the specified {@code int} value. This function is 1669 * sometimes referred to as the <i>population count</i>. 1670 * 1671 * @param i the value whose bits are to be counted 1672 * @return the number of one-bits in the two's complement binary 1673 * representation of the specified {@code int} value. 1674 * @since 1.5 1675 */ 1676 @HotSpotIntrinsicCandidate 1677 public static int bitCount(int i) { 1678 // HD, Figure 5-2 1679 i = i - ((i >>> 1) & 0x55555555); 1680 i = (i & 0x33333333) + ((i >>> 2) & 0x33333333); 1681 i = (i + (i >>> 4)) & 0x0f0f0f0f; 1682 i = i + (i >>> 8); 1683 i = i + (i >>> 16); 1684 return i & 0x3f; 1685 } 1686 1687 /** 1688 * Returns the value obtained by rotating the two's complement binary 1689 * representation of the specified {@code int} value left by the 1690 * specified number of bits. (Bits shifted out of the left hand, or 1691 * high-order, side reenter on the right, or low-order.) 1692 * 1693 * <p>Note that left rotation with a negative distance is equivalent to 1694 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val, 1695 * distance)}. Note also that rotation by any multiple of 32 is a 1696 * no-op, so all but the last five bits of the rotation distance can be 1697 * ignored, even if the distance is negative: {@code rotateLeft(val, 1698 * distance) == rotateLeft(val, distance & 0x1F)}. 1699 * 1700 * @param i the value whose bits are to be rotated left 1701 * @param distance the number of bit positions to rotate left 1702 * @return the value obtained by rotating the two's complement binary 1703 * representation of the specified {@code int} value left by the 1704 * specified number of bits. 1705 * @since 1.5 1706 */ 1707 public static int rotateLeft(int i, int distance) { 1708 return (i << distance) | (i >>> -distance); 1709 } 1710 1711 /** 1712 * Returns the value obtained by rotating the two's complement binary 1713 * representation of the specified {@code int} value right by the 1714 * specified number of bits. (Bits shifted out of the right hand, or 1715 * low-order, side reenter on the left, or high-order.) 1716 * 1717 * <p>Note that right rotation with a negative distance is equivalent to 1718 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val, 1719 * distance)}. Note also that rotation by any multiple of 32 is a 1720 * no-op, so all but the last five bits of the rotation distance can be 1721 * ignored, even if the distance is negative: {@code rotateRight(val, 1722 * distance) == rotateRight(val, distance & 0x1F)}. 1723 * 1724 * @param i the value whose bits are to be rotated right 1725 * @param distance the number of bit positions to rotate right 1726 * @return the value obtained by rotating the two's complement binary 1727 * representation of the specified {@code int} value right by the 1728 * specified number of bits. 1729 * @since 1.5 1730 */ 1731 public static int rotateRight(int i, int distance) { 1732 return (i >>> distance) | (i << -distance); 1733 } 1734 1735 /** 1736 * Returns the value obtained by reversing the order of the bits in the 1737 * two's complement binary representation of the specified {@code int} 1738 * value. 1739 * 1740 * @param i the value to be reversed 1741 * @return the value obtained by reversing order of the bits in the 1742 * specified {@code int} value. 1743 * @since 1.5 1744 */ 1745 public static int reverse(int i) { 1746 // HD, Figure 7-1 1747 i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555; 1748 i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333; 1749 i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f; 1750 1751 return reverseBytes(i); 1752 } 1753 1754 /** 1755 * Returns the signum function of the specified {@code int} value. (The 1756 * return value is -1 if the specified value is negative; 0 if the 1757 * specified value is zero; and 1 if the specified value is positive.) 1758 * 1759 * @param i the value whose signum is to be computed 1760 * @return the signum function of the specified {@code int} value. 1761 * @since 1.5 1762 */ 1763 public static int signum(int i) { 1764 // HD, Section 2-7 1765 return (i >> 31) | (-i >>> 31); 1766 } 1767 1768 /** 1769 * Returns the value obtained by reversing the order of the bytes in the 1770 * two's complement representation of the specified {@code int} value. 1771 * 1772 * @param i the value whose bytes are to be reversed 1773 * @return the value obtained by reversing the bytes in the specified 1774 * {@code int} value. 1775 * @since 1.5 1776 */ 1777 @HotSpotIntrinsicCandidate 1778 public static int reverseBytes(int i) { 1779 return (i << 24) | 1780 ((i & 0xff00) << 8) | 1781 ((i >>> 8) & 0xff00) | 1782 (i >>> 24); 1783 } 1784 1785 /** 1786 * Adds two integers together as per the + operator. 1787 * 1788 * @param a the first operand 1789 * @param b the second operand 1790 * @return the sum of {@code a} and {@code b} 1791 * @see java.util.function.BinaryOperator 1792 * @since 1.8 1793 */ 1794 public static int sum(int a, int b) { 1795 return a + b; 1796 } 1797 1798 /** 1799 * Returns the greater of two {@code int} values 1800 * as if by calling {@link Math#max(int, int) Math.max}. 1801 * 1802 * @param a the first operand 1803 * @param b the second operand 1804 * @return the greater of {@code a} and {@code b} 1805 * @see java.util.function.BinaryOperator 1806 * @since 1.8 1807 */ 1808 public static int max(int a, int b) { 1809 return Math.max(a, b); 1810 } 1811 1812 /** 1813 * Returns the smaller of two {@code int} values 1814 * as if by calling {@link Math#min(int, int) Math.min}. 1815 * 1816 * @param a the first operand 1817 * @param b the second operand 1818 * @return the smaller of {@code a} and {@code b} 1819 * @see java.util.function.BinaryOperator 1820 * @since 1.8 1821 */ 1822 public static int min(int a, int b) { 1823 return Math.min(a, b); 1824 } 1825 1826 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 1827 @Native private static final long serialVersionUID = 1360826667806852920L; 1828} 1829