1 /* 2 * Copyright (c) 1994, 2016, 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 java.lang.annotation.Native; 29 import java.util.Objects; 30 import jdk.internal.HotSpotIntrinsicCandidate; 31 import jdk.internal.misc.VM; 32 33 import static java.lang.String.COMPACT_STRINGS; 34 import static java.lang.String.LATIN1; 35 import 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 */ 59 public 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 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 getCharsUTF16(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 /** 520 * This is a variant of {@link #getChars(int, int, byte[])}, but for 521 * UTF-16 coder. 522 * 523 * @param i value to convert 524 * @param index next index, after the least significant digit 525 * @param buf target buffer, UTF16-coded. 526 * @return index of the most significant digit or minus sign, if present 527 */ 528 static int getCharsUTF16(int i, int index, byte[] buf) { 529 int q, r; 530 int charPos = index; 531 532 boolean negative = (i < 0); 533 if (!negative) { 534 i = -i; 535 } 536 537 // Get 2 digits/iteration using ints 538 while (i <= -100) { 539 q = i / 100; 540 r = (q * 100) - i; 541 i = q; 542 StringUTF16.putChar(buf, --charPos, DigitOnes[r]); 543 StringUTF16.putChar(buf, --charPos, DigitTens[r]); 544 } 545 546 // We know there are at most two digits left at this point. 547 q = i / 10; 548 r = (q * 10) - i; 549 StringUTF16.putChar(buf, --charPos, '0' + r); 550 551 // Whatever left is the remaining digit. 552 if (q < 0) { 553 StringUTF16.putChar(buf, --charPos, '0' - q); 554 } 555 556 if (negative) { 557 StringUTF16.putChar(buf, --charPos, '-'); 558 } 559 return charPos; 560 } 561 562 // Left here for compatibility reasons, see JDK-8143900. 563 static final int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999, 564 99999999, 999999999, Integer.MAX_VALUE }; 565 566 /** 567 * Returns the string representation size for a given int value. 568 * 569 * @param x int value 570 * @return string size 571 * 572 * @implNote There are other ways to compute this: e.g. binary search, 573 * but values are biased heavily towards zero, and therefore linear search 574 * wins. The iteration results are also routinely inlined in the generated 575 * code after loop unrolling. 576 */ 577 static int stringSize(int x) { 578 int d = 1; 579 if (x >= 0) { 580 d = 0; 581 x = -x; 582 } 583 int p = -10; 584 for (int i = 1; i < 10; i++) { 585 if (x > p) 586 return i + d; 587 p = 10 * p; 588 } 589 return 10 + d; 590 } 591 592 /** 593 * Parses the string argument as a signed integer in the radix 594 * specified by the second argument. The characters in the string 595 * must all be digits of the specified radix (as determined by 596 * whether {@link java.lang.Character#digit(char, int)} returns a 597 * nonnegative value), except that the first character may be an 598 * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to 599 * indicate a negative value or an ASCII plus sign {@code '+'} 600 * ({@code '\u005Cu002B'}) to indicate a positive value. The 601 * resulting integer value is returned. 602 * 603 * <p>An exception of type {@code NumberFormatException} is 604 * thrown if any of the following situations occurs: 605 * <ul> 606 * <li>The first argument is {@code null} or is a string of 607 * length zero. 608 * 609 * <li>The radix is either smaller than 610 * {@link java.lang.Character#MIN_RADIX} or 611 * larger than {@link java.lang.Character#MAX_RADIX}. 612 * 613 * <li>Any character of the string is not a digit of the specified 614 * radix, except that the first character may be a minus sign 615 * {@code '-'} ({@code '\u005Cu002D'}) or plus sign 616 * {@code '+'} ({@code '\u005Cu002B'}) provided that the 617 * string is longer than length 1. 618 * 619 * <li>The value represented by the string is not a value of type 620 * {@code int}. 621 * </ul> 622 * 623 * <p>Examples: 624 * <blockquote><pre> 625 * parseInt("0", 10) returns 0 626 * parseInt("473", 10) returns 473 627 * parseInt("+42", 10) returns 42 628 * parseInt("-0", 10) returns 0 629 * parseInt("-FF", 16) returns -255 630 * parseInt("1100110", 2) returns 102 631 * parseInt("2147483647", 10) returns 2147483647 632 * parseInt("-2147483648", 10) returns -2147483648 633 * parseInt("2147483648", 10) throws a NumberFormatException 634 * parseInt("99", 8) throws a NumberFormatException 635 * parseInt("Kona", 10) throws a NumberFormatException 636 * parseInt("Kona", 27) returns 411787 637 * </pre></blockquote> 638 * 639 * @param s the {@code String} containing the integer 640 * representation to be parsed 641 * @param radix the radix to be used while parsing {@code s}. 642 * @return the integer represented by the string argument in the 643 * specified radix. 644 * @exception NumberFormatException if the {@code String} 645 * does not contain a parsable {@code int}. 646 */ 647 public static int parseInt(String s, int radix) 648 throws NumberFormatException 649 { 650 /* 651 * WARNING: This method may be invoked early during VM initialization 652 * before IntegerCache is initialized. Care must be taken to not use 653 * the valueOf method. 654 */ 655 656 if (s == null) { 657 throw new NumberFormatException("null"); 658 } 659 660 if (radix < Character.MIN_RADIX) { 661 throw new NumberFormatException("radix " + radix + 662 " less than Character.MIN_RADIX"); 663 } 664 665 if (radix > Character.MAX_RADIX) { 666 throw new NumberFormatException("radix " + radix + 667 " greater than Character.MAX_RADIX"); 668 } 669 670 boolean negative = false; 671 int i = 0, len = s.length(); 672 int limit = -Integer.MAX_VALUE; 673 674 if (len > 0) { 675 char firstChar = s.charAt(0); 676 if (firstChar < '0') { // Possible leading "+" or "-" 677 if (firstChar == '-') { 678 negative = true; 679 limit = Integer.MIN_VALUE; 680 } else if (firstChar != '+') { 681 throw NumberFormatException.forInputString(s); 682 } 683 684 if (len == 1) { // Cannot have lone "+" or "-" 685 throw NumberFormatException.forInputString(s); 686 } 687 i++; 688 } 689 int multmin = limit / radix; 690 int result = 0; 691 while (i < len) { 692 // Accumulating negatively avoids surprises near MAX_VALUE 693 int digit = Character.digit(s.charAt(i++), radix); 694 if (digit < 0 || result < multmin) { 695 throw NumberFormatException.forInputString(s); 696 } 697 result *= radix; 698 if (result < limit + digit) { 699 throw NumberFormatException.forInputString(s); 700 } 701 result -= digit; 702 } 703 return negative ? result : -result; 704 } else { 705 throw NumberFormatException.forInputString(s); 706 } 707 } 708 709 /** 710 * Parses the {@link CharSequence} argument as a signed {@code int} in the 711 * specified {@code radix}, beginning at the specified {@code beginIndex} 712 * and extending to {@code endIndex - 1}. 713 * 714 * <p>The method does not take steps to guard against the 715 * {@code CharSequence} being mutated while parsing. 716 * 717 * @param s the {@code CharSequence} containing the {@code int} 718 * representation to be parsed 719 * @param beginIndex the beginning index, inclusive. 720 * @param endIndex the ending index, exclusive. 721 * @param radix the radix to be used while parsing {@code s}. 722 * @return the signed {@code int} represented by the subsequence in 723 * the specified radix. 724 * @throws NullPointerException if {@code s} is null. 725 * @throws IndexOutOfBoundsException if {@code beginIndex} is 726 * negative, or if {@code beginIndex} is greater than 727 * {@code endIndex} or if {@code endIndex} is greater than 728 * {@code s.length()}. 729 * @throws NumberFormatException if the {@code CharSequence} does not 730 * contain a parsable {@code int} in the specified 731 * {@code radix}, or if {@code radix} is either smaller than 732 * {@link java.lang.Character#MIN_RADIX} or larger than 733 * {@link java.lang.Character#MAX_RADIX}. 734 * @since 9 735 */ 736 public static int parseInt(CharSequence s, int beginIndex, int endIndex, int radix) 737 throws NumberFormatException { 738 s = Objects.requireNonNull(s); 739 740 if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) { 741 throw new IndexOutOfBoundsException(); 742 } 743 if (radix < Character.MIN_RADIX) { 744 throw new NumberFormatException("radix " + radix + 745 " less than Character.MIN_RADIX"); 746 } 747 if (radix > Character.MAX_RADIX) { 748 throw new NumberFormatException("radix " + radix + 749 " greater than Character.MAX_RADIX"); 750 } 751 752 boolean negative = false; 753 int i = beginIndex; 754 int limit = -Integer.MAX_VALUE; 755 756 if (i < endIndex) { 757 char firstChar = s.charAt(i); 758 if (firstChar < '0') { // Possible leading "+" or "-" 759 if (firstChar == '-') { 760 negative = true; 761 limit = Integer.MIN_VALUE; 762 } else if (firstChar != '+') { 763 throw NumberFormatException.forCharSequence(s, beginIndex, 764 endIndex, i); 765 } 766 i++; 767 if (i == endIndex) { // Cannot have lone "+" or "-" 768 throw NumberFormatException.forCharSequence(s, beginIndex, 769 endIndex, i); 770 } 771 } 772 int multmin = limit / radix; 773 int result = 0; 774 while (i < endIndex) { 775 // Accumulating negatively avoids surprises near MAX_VALUE 776 int digit = Character.digit(s.charAt(i), radix); 777 if (digit < 0 || result < multmin) { 778 throw NumberFormatException.forCharSequence(s, beginIndex, 779 endIndex, i); 780 } 781 result *= radix; 782 if (result < limit + digit) { 783 throw NumberFormatException.forCharSequence(s, beginIndex, 784 endIndex, i); 785 } 786 i++; 787 result -= digit; 788 } 789 return negative ? result : -result; 790 } else { 791 throw NumberFormatException.forInputString(""); 792 } 793 } 794 795 /** 796 * Parses the string argument as a signed decimal integer. The 797 * characters in the string must all be decimal digits, except 798 * that the first character may be an ASCII minus sign {@code '-'} 799 * ({@code '\u005Cu002D'}) to indicate a negative value or an 800 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to 801 * indicate a positive value. The resulting integer value is 802 * returned, exactly as if the argument and the radix 10 were 803 * given as arguments to the {@link #parseInt(java.lang.String, 804 * int)} method. 805 * 806 * @param s a {@code String} containing the {@code int} 807 * representation to be parsed 808 * @return the integer value represented by the argument in decimal. 809 * @exception NumberFormatException if the string does not contain a 810 * parsable integer. 811 */ 812 public static int parseInt(String s) throws NumberFormatException { 813 return parseInt(s,10); 814 } 815 816 /** 817 * Parses the string argument as an unsigned integer in the radix 818 * specified by the second argument. An unsigned integer maps the 819 * values usually associated with negative numbers to positive 820 * numbers larger than {@code MAX_VALUE}. 821 * 822 * The characters in the string must all be digits of the 823 * specified radix (as determined by whether {@link 824 * java.lang.Character#digit(char, int)} returns a nonnegative 825 * value), except that the first character may be an ASCII plus 826 * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting 827 * integer value is returned. 828 * 829 * <p>An exception of type {@code NumberFormatException} is 830 * thrown if any of the following situations occurs: 831 * <ul> 832 * <li>The first argument is {@code null} or is a string of 833 * length zero. 834 * 835 * <li>The radix is either smaller than 836 * {@link java.lang.Character#MIN_RADIX} or 837 * larger than {@link java.lang.Character#MAX_RADIX}. 838 * 839 * <li>Any character of the string is not a digit of the specified 840 * radix, except that the first character may be a plus sign 841 * {@code '+'} ({@code '\u005Cu002B'}) provided that the 842 * string is longer than length 1. 843 * 844 * <li>The value represented by the string is larger than the 845 * largest unsigned {@code int}, 2<sup>32</sup>-1. 846 * 847 * </ul> 848 * 849 * 850 * @param s the {@code String} containing the unsigned integer 851 * representation to be parsed 852 * @param radix the radix to be used while parsing {@code s}. 853 * @return the integer represented by the string argument in the 854 * specified radix. 855 * @throws NumberFormatException if the {@code String} 856 * does not contain a parsable {@code int}. 857 * @since 1.8 858 */ 859 public static int parseUnsignedInt(String s, int radix) 860 throws NumberFormatException { 861 if (s == null) { 862 throw new NumberFormatException("null"); 863 } 864 865 int len = s.length(); 866 if (len > 0) { 867 char firstChar = s.charAt(0); 868 if (firstChar == '-') { 869 throw new 870 NumberFormatException(String.format("Illegal leading minus sign " + 871 "on unsigned string %s.", s)); 872 } else { 873 if (len <= 5 || // Integer.MAX_VALUE in Character.MAX_RADIX is 6 digits 874 (radix == 10 && len <= 9) ) { // Integer.MAX_VALUE in base 10 is 10 digits 875 return parseInt(s, radix); 876 } else { 877 long ell = Long.parseLong(s, radix); 878 if ((ell & 0xffff_ffff_0000_0000L) == 0) { 879 return (int) ell; 880 } else { 881 throw new 882 NumberFormatException(String.format("String value %s exceeds " + 883 "range of unsigned int.", s)); 884 } 885 } 886 } 887 } else { 888 throw NumberFormatException.forInputString(s); 889 } 890 } 891 892 /** 893 * Parses the {@link CharSequence} argument as an unsigned {@code int} in 894 * the specified {@code radix}, beginning at the specified 895 * {@code beginIndex} and extending to {@code endIndex - 1}. 896 * 897 * <p>The method does not take steps to guard against the 898 * {@code CharSequence} being mutated while parsing. 899 * 900 * @param s the {@code CharSequence} containing the unsigned 901 * {@code int} representation to be parsed 902 * @param beginIndex the beginning index, inclusive. 903 * @param endIndex the ending index, exclusive. 904 * @param radix the radix to be used while parsing {@code s}. 905 * @return the unsigned {@code int} represented by the subsequence in 906 * the specified radix. 907 * @throws NullPointerException if {@code s} is null. 908 * @throws IndexOutOfBoundsException if {@code beginIndex} is 909 * negative, or if {@code beginIndex} is greater than 910 * {@code endIndex} or if {@code endIndex} is greater than 911 * {@code s.length()}. 912 * @throws NumberFormatException if the {@code CharSequence} does not 913 * contain a parsable unsigned {@code int} in the specified 914 * {@code radix}, or if {@code radix} is either smaller than 915 * {@link java.lang.Character#MIN_RADIX} or larger than 916 * {@link java.lang.Character#MAX_RADIX}. 917 * @since 9 918 */ 919 public static int parseUnsignedInt(CharSequence s, int beginIndex, int endIndex, int radix) 920 throws NumberFormatException { 921 s = Objects.requireNonNull(s); 922 923 if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) { 924 throw new IndexOutOfBoundsException(); 925 } 926 int start = beginIndex, len = endIndex - beginIndex; 927 928 if (len > 0) { 929 char firstChar = s.charAt(start); 930 if (firstChar == '-') { 931 throw new 932 NumberFormatException(String.format("Illegal leading minus sign " + 933 "on unsigned string %s.", s)); 934 } else { 935 if (len <= 5 || // Integer.MAX_VALUE in Character.MAX_RADIX is 6 digits 936 (radix == 10 && len <= 9)) { // Integer.MAX_VALUE in base 10 is 10 digits 937 return parseInt(s, start, start + len, radix); 938 } else { 939 long ell = Long.parseLong(s, start, start + len, radix); 940 if ((ell & 0xffff_ffff_0000_0000L) == 0) { 941 return (int) ell; 942 } else { 943 throw new 944 NumberFormatException(String.format("String value %s exceeds " + 945 "range of unsigned int.", s)); 946 } 947 } 948 } 949 } else { 950 throw new NumberFormatException(""); 951 } 952 } 953 954 /** 955 * Parses the string argument as an unsigned decimal integer. The 956 * characters in the string must all be decimal digits, except 957 * that the first character may be an ASCII plus sign {@code 958 * '+'} ({@code '\u005Cu002B'}). The resulting integer value 959 * is returned, exactly as if the argument and the radix 10 were 960 * given as arguments to the {@link 961 * #parseUnsignedInt(java.lang.String, int)} method. 962 * 963 * @param s a {@code String} containing the unsigned {@code int} 964 * representation to be parsed 965 * @return the unsigned integer value represented by the argument in decimal. 966 * @throws NumberFormatException if the string does not contain a 967 * parsable unsigned integer. 968 * @since 1.8 969 */ 970 public static int parseUnsignedInt(String s) throws NumberFormatException { 971 return parseUnsignedInt(s, 10); 972 } 973 974 /** 975 * Returns an {@code Integer} object holding the value 976 * extracted from the specified {@code String} when parsed 977 * with the radix given by the second argument. The first argument 978 * is interpreted as representing a signed integer in the radix 979 * specified by the second argument, exactly as if the arguments 980 * were given to the {@link #parseInt(java.lang.String, int)} 981 * method. The result is an {@code Integer} object that 982 * represents the integer value specified by the string. 983 * 984 * <p>In other words, this method returns an {@code Integer} 985 * object equal to the value of: 986 * 987 * <blockquote> 988 * {@code new Integer(Integer.parseInt(s, radix))} 989 * </blockquote> 990 * 991 * @param s the string to be parsed. 992 * @param radix the radix to be used in interpreting {@code s} 993 * @return an {@code Integer} object holding the value 994 * represented by the string argument in the specified 995 * radix. 996 * @exception NumberFormatException if the {@code String} 997 * does not contain a parsable {@code int}. 998 */ 999 public static Integer valueOf(String s, int radix) throws NumberFormatException { 1000 return Integer.valueOf(parseInt(s,radix)); 1001 } 1002 1003 /** 1004 * Returns an {@code Integer} object holding the 1005 * value of the specified {@code String}. The argument is 1006 * interpreted as representing a signed decimal integer, exactly 1007 * as if the argument were given to the {@link 1008 * #parseInt(java.lang.String)} method. The result is an 1009 * {@code Integer} object that represents the integer value 1010 * specified by the string. 1011 * 1012 * <p>In other words, this method returns an {@code Integer} 1013 * object equal to the value of: 1014 * 1015 * <blockquote> 1016 * {@code new Integer(Integer.parseInt(s))} 1017 * </blockquote> 1018 * 1019 * @param s the string to be parsed. 1020 * @return an {@code Integer} object holding the value 1021 * represented by the string argument. 1022 * @exception NumberFormatException if the string cannot be parsed 1023 * as an integer. 1024 */ 1025 public static Integer valueOf(String s) throws NumberFormatException { 1026 return Integer.valueOf(parseInt(s, 10)); 1027 } 1028 1029 /** 1030 * Cache to support the object identity semantics of autoboxing for values between 1031 * -128 and 127 (inclusive) as required by JLS. 1032 * 1033 * The cache is initialized on first usage. The size of the cache 1034 * may be controlled by the {@code -XX:AutoBoxCacheMax=<size>} option. 1035 * During VM initialization, java.lang.Integer.IntegerCache.high property 1036 * may be set and saved in the private system properties in the 1037 * jdk.internal.misc.VM class. 1038 */ 1039 1040 private static class IntegerCache { 1041 static final int low = -128; 1042 static final int high; 1043 static final Integer cache[]; 1044 1045 static { 1046 // high value may be configured by property 1047 int h = 127; 1048 String integerCacheHighPropValue = 1049 VM.getSavedProperty("java.lang.Integer.IntegerCache.high"); 1050 if (integerCacheHighPropValue != null) { 1051 try { 1052 int i = parseInt(integerCacheHighPropValue); 1053 i = Math.max(i, 127); 1054 // Maximum array size is Integer.MAX_VALUE 1055 h = Math.min(i, Integer.MAX_VALUE - (-low) -1); 1056 } catch( NumberFormatException nfe) { 1057 // If the property cannot be parsed into an int, ignore it. 1058 } 1059 } 1060 high = h; 1061 1062 cache = new Integer[(high - low) + 1]; 1063 int j = low; 1064 for(int k = 0; k < cache.length; k++) 1065 cache[k] = new Integer(j++); 1066 1067 // range [-128, 127] must be interned (JLS7 5.1.7) 1068 assert IntegerCache.high >= 127; 1069 } 1070 1071 private IntegerCache() {} 1072 } 1073 1074 /** 1075 * Returns an {@code Integer} instance representing the specified 1076 * {@code int} value. If a new {@code Integer} instance is not 1077 * required, this method should generally be used in preference to 1078 * the constructor {@link #Integer(int)}, as this method is likely 1079 * to yield significantly better space and time performance by 1080 * caching frequently requested values. 1081 * 1082 * This method will always cache values in the range -128 to 127, 1083 * inclusive, and may cache other values outside of this range. 1084 * 1085 * @param i an {@code int} value. 1086 * @return an {@code Integer} instance representing {@code i}. 1087 * @since 1.5 1088 */ 1089 @HotSpotIntrinsicCandidate 1090 public static Integer valueOf(int i) { 1091 if (i >= IntegerCache.low && i <= IntegerCache.high) 1092 return IntegerCache.cache[i + (-IntegerCache.low)]; 1093 return new Integer(i); 1094 } 1095 1096 /** 1097 * The value of the {@code Integer}. 1098 * 1099 * @serial 1100 */ 1101 private final int value; 1102 1103 /** 1104 * Constructs a newly allocated {@code Integer} object that 1105 * represents the specified {@code int} value. 1106 * 1107 * @param value the value to be represented by the 1108 * {@code Integer} object. 1109 * 1110 * @deprecated 1111 * It is rarely appropriate to use this constructor. The static factory 1112 * {@link #valueOf(int)} is generally a better choice, as it is 1113 * likely to yield significantly better space and time performance. 1114 */ 1115 @Deprecated(since="9") 1116 public Integer(int value) { 1117 this.value = value; 1118 } 1119 1120 /** 1121 * Constructs a newly allocated {@code Integer} object that 1122 * represents the {@code int} value indicated by the 1123 * {@code String} parameter. The string is converted to an 1124 * {@code int} value in exactly the manner used by the 1125 * {@code parseInt} method for radix 10. 1126 * 1127 * @param s the {@code String} to be converted to an {@code Integer}. 1128 * @throws NumberFormatException if the {@code String} does not 1129 * contain a parsable integer. 1130 * 1131 * @deprecated 1132 * It is rarely appropriate to use this constructor. 1133 * Use {@link #parseInt(String)} to convert a string to a 1134 * {@code int} primitive, or use {@link #valueOf(String)} 1135 * to convert a string to an {@code Integer} object. 1136 */ 1137 @Deprecated(since="9") 1138 public Integer(String s) throws NumberFormatException { 1139 this.value = parseInt(s, 10); 1140 } 1141 1142 /** 1143 * Returns the value of this {@code Integer} as a {@code byte} 1144 * after a narrowing primitive conversion. 1145 * @jls 5.1.3 Narrowing Primitive Conversions 1146 */ 1147 public byte byteValue() { 1148 return (byte)value; 1149 } 1150 1151 /** 1152 * Returns the value of this {@code Integer} as a {@code short} 1153 * after a narrowing primitive conversion. 1154 * @jls 5.1.3 Narrowing Primitive Conversions 1155 */ 1156 public short shortValue() { 1157 return (short)value; 1158 } 1159 1160 /** 1161 * Returns the value of this {@code Integer} as an 1162 * {@code int}. 1163 */ 1164 @HotSpotIntrinsicCandidate 1165 public int intValue() { 1166 return value; 1167 } 1168 1169 /** 1170 * Returns the value of this {@code Integer} as a {@code long} 1171 * after a widening primitive conversion. 1172 * @jls 5.1.2 Widening Primitive Conversions 1173 * @see Integer#toUnsignedLong(int) 1174 */ 1175 public long longValue() { 1176 return (long)value; 1177 } 1178 1179 /** 1180 * Returns the value of this {@code Integer} as a {@code float} 1181 * after a widening primitive conversion. 1182 * @jls 5.1.2 Widening Primitive Conversions 1183 */ 1184 public float floatValue() { 1185 return (float)value; 1186 } 1187 1188 /** 1189 * Returns the value of this {@code Integer} as a {@code double} 1190 * after a widening primitive conversion. 1191 * @jls 5.1.2 Widening Primitive Conversions 1192 */ 1193 public double doubleValue() { 1194 return (double)value; 1195 } 1196 1197 /** 1198 * Returns a {@code String} object representing this 1199 * {@code Integer}'s value. The value is converted to signed 1200 * decimal representation and returned as a string, exactly as if 1201 * the integer value were given as an argument to the {@link 1202 * java.lang.Integer#toString(int)} method. 1203 * 1204 * @return a string representation of the value of this object in 1205 * base 10. 1206 */ 1207 public String toString() { 1208 return toString(value); 1209 } 1210 1211 /** 1212 * Returns a hash code for this {@code Integer}. 1213 * 1214 * @return a hash code value for this object, equal to the 1215 * primitive {@code int} value represented by this 1216 * {@code Integer} object. 1217 */ 1218 @Override 1219 public int hashCode() { 1220 return Integer.hashCode(value); 1221 } 1222 1223 /** 1224 * Returns a hash code for a {@code int} value; compatible with 1225 * {@code Integer.hashCode()}. 1226 * 1227 * @param value the value to hash 1228 * @since 1.8 1229 * 1230 * @return a hash code value for a {@code int} value. 1231 */ 1232 public static int hashCode(int value) { 1233 return value; 1234 } 1235 1236 /** 1237 * Compares this object to the specified object. The result is 1238 * {@code true} if and only if the argument is not 1239 * {@code null} and is an {@code Integer} object that 1240 * contains the same {@code int} value as this object. 1241 * 1242 * @param obj the object to compare with. 1243 * @return {@code true} if the objects are the same; 1244 * {@code false} otherwise. 1245 */ 1246 public boolean equals(Object obj) { 1247 if (obj instanceof Integer) { 1248 return value == ((Integer)obj).intValue(); 1249 } 1250 return false; 1251 } 1252 1253 /** 1254 * Determines the integer value of the system property with the 1255 * specified name. 1256 * 1257 * <p>The first argument is treated as the name of a system 1258 * property. System properties are accessible through the {@link 1259 * java.lang.System#getProperty(java.lang.String)} method. The 1260 * string value of this property is then interpreted as an integer 1261 * value using the grammar supported by {@link Integer#decode decode} and 1262 * an {@code Integer} object representing this value is returned. 1263 * 1264 * <p>If there is no property with the specified name, if the 1265 * specified name is empty or {@code null}, or if the property 1266 * does not have the correct numeric format, then {@code null} is 1267 * returned. 1268 * 1269 * <p>In other words, this method returns an {@code Integer} 1270 * object equal to the value of: 1271 * 1272 * <blockquote> 1273 * {@code getInteger(nm, null)} 1274 * </blockquote> 1275 * 1276 * @param nm property name. 1277 * @return the {@code Integer} value of the property. 1278 * @throws SecurityException for the same reasons as 1279 * {@link System#getProperty(String) System.getProperty} 1280 * @see java.lang.System#getProperty(java.lang.String) 1281 * @see java.lang.System#getProperty(java.lang.String, java.lang.String) 1282 */ 1283 public static Integer getInteger(String nm) { 1284 return getInteger(nm, null); 1285 } 1286 1287 /** 1288 * Determines the integer value of the system property with the 1289 * specified name. 1290 * 1291 * <p>The first argument is treated as the name of a system 1292 * property. System properties are accessible through the {@link 1293 * java.lang.System#getProperty(java.lang.String)} method. The 1294 * string value of this property is then interpreted as an integer 1295 * value using the grammar supported by {@link Integer#decode decode} and 1296 * an {@code Integer} object representing this value is returned. 1297 * 1298 * <p>The second argument is the default value. An {@code Integer} object 1299 * that represents the value of the second argument is returned if there 1300 * is no property of the specified name, if the property does not have 1301 * the correct numeric format, or if the specified name is empty or 1302 * {@code null}. 1303 * 1304 * <p>In other words, this method returns an {@code Integer} object 1305 * equal to the value of: 1306 * 1307 * <blockquote> 1308 * {@code getInteger(nm, new Integer(val))} 1309 * </blockquote> 1310 * 1311 * but in practice it may be implemented in a manner such as: 1312 * 1313 * <blockquote><pre> 1314 * Integer result = getInteger(nm, null); 1315 * return (result == null) ? new Integer(val) : result; 1316 * </pre></blockquote> 1317 * 1318 * to avoid the unnecessary allocation of an {@code Integer} 1319 * object when the default value is not needed. 1320 * 1321 * @param nm property name. 1322 * @param val default value. 1323 * @return the {@code Integer} value of the property. 1324 * @throws SecurityException for the same reasons as 1325 * {@link System#getProperty(String) System.getProperty} 1326 * @see java.lang.System#getProperty(java.lang.String) 1327 * @see java.lang.System#getProperty(java.lang.String, java.lang.String) 1328 */ 1329 public static Integer getInteger(String nm, int val) { 1330 Integer result = getInteger(nm, null); 1331 return (result == null) ? Integer.valueOf(val) : result; 1332 } 1333 1334 /** 1335 * Returns the integer value of the system property with the 1336 * specified name. The first argument is treated as the name of a 1337 * system property. System properties are accessible through the 1338 * {@link java.lang.System#getProperty(java.lang.String)} method. 1339 * The string value of this property is then interpreted as an 1340 * integer value, as per the {@link Integer#decode decode} method, 1341 * and an {@code Integer} object representing this value is 1342 * returned; in summary: 1343 * 1344 * <ul><li>If the property value begins with the two ASCII characters 1345 * {@code 0x} or the ASCII character {@code #}, not 1346 * followed by a minus sign, then the rest of it is parsed as a 1347 * hexadecimal integer exactly as by the method 1348 * {@link #valueOf(java.lang.String, int)} with radix 16. 1349 * <li>If the property value begins with the ASCII character 1350 * {@code 0} followed by another character, it is parsed as an 1351 * octal integer exactly as by the method 1352 * {@link #valueOf(java.lang.String, int)} with radix 8. 1353 * <li>Otherwise, the property value is parsed as a decimal integer 1354 * exactly as by the method {@link #valueOf(java.lang.String, int)} 1355 * with radix 10. 1356 * </ul> 1357 * 1358 * <p>The second argument is the default value. The default value is 1359 * returned if there is no property of the specified name, if the 1360 * property does not have the correct numeric format, or if the 1361 * specified name is empty or {@code null}. 1362 * 1363 * @param nm property name. 1364 * @param val default value. 1365 * @return the {@code Integer} value of the property. 1366 * @throws SecurityException for the same reasons as 1367 * {@link System#getProperty(String) System.getProperty} 1368 * @see System#getProperty(java.lang.String) 1369 * @see System#getProperty(java.lang.String, java.lang.String) 1370 */ 1371 public static Integer getInteger(String nm, Integer val) { 1372 String v = null; 1373 try { 1374 v = System.getProperty(nm); 1375 } catch (IllegalArgumentException | NullPointerException e) { 1376 } 1377 if (v != null) { 1378 try { 1379 return Integer.decode(v); 1380 } catch (NumberFormatException e) { 1381 } 1382 } 1383 return val; 1384 } 1385 1386 /** 1387 * Decodes a {@code String} into an {@code Integer}. 1388 * Accepts decimal, hexadecimal, and octal numbers given 1389 * by the following grammar: 1390 * 1391 * <blockquote> 1392 * <dl> 1393 * <dt><i>DecodableString:</i> 1394 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i> 1395 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i> 1396 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i> 1397 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i> 1398 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i> 1399 * 1400 * <dt><i>Sign:</i> 1401 * <dd>{@code -} 1402 * <dd>{@code +} 1403 * </dl> 1404 * </blockquote> 1405 * 1406 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i> 1407 * are as defined in section 3.10.1 of 1408 * <cite>The Java™ Language Specification</cite>, 1409 * except that underscores are not accepted between digits. 1410 * 1411 * <p>The sequence of characters following an optional 1412 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}", 1413 * "{@code #}", or leading zero) is parsed as by the {@code 1414 * Integer.parseInt} method with the indicated radix (10, 16, or 1415 * 8). This sequence of characters must represent a positive 1416 * value or a {@link NumberFormatException} will be thrown. The 1417 * result is negated if first character of the specified {@code 1418 * String} is the minus sign. No whitespace characters are 1419 * permitted in the {@code String}. 1420 * 1421 * @param nm the {@code String} to decode. 1422 * @return an {@code Integer} object holding the {@code int} 1423 * value represented by {@code nm} 1424 * @exception NumberFormatException if the {@code String} does not 1425 * contain a parsable integer. 1426 * @see java.lang.Integer#parseInt(java.lang.String, int) 1427 */ 1428 public static Integer decode(String nm) throws NumberFormatException { 1429 int radix = 10; 1430 int index = 0; 1431 boolean negative = false; 1432 Integer result; 1433 1434 if (nm.length() == 0) 1435 throw new NumberFormatException("Zero length string"); 1436 char firstChar = nm.charAt(0); 1437 // Handle sign, if present 1438 if (firstChar == '-') { 1439 negative = true; 1440 index++; 1441 } else if (firstChar == '+') 1442 index++; 1443 1444 // Handle radix specifier, if present 1445 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) { 1446 index += 2; 1447 radix = 16; 1448 } 1449 else if (nm.startsWith("#", index)) { 1450 index ++; 1451 radix = 16; 1452 } 1453 else if (nm.startsWith("0", index) && nm.length() > 1 + index) { 1454 index ++; 1455 radix = 8; 1456 } 1457 1458 if (nm.startsWith("-", index) || nm.startsWith("+", index)) 1459 throw new NumberFormatException("Sign character in wrong position"); 1460 1461 try { 1462 result = Integer.valueOf(nm.substring(index), radix); 1463 result = negative ? Integer.valueOf(-result.intValue()) : result; 1464 } catch (NumberFormatException e) { 1465 // If number is Integer.MIN_VALUE, we'll end up here. The next line 1466 // handles this case, and causes any genuine format error to be 1467 // rethrown. 1468 String constant = negative ? ("-" + nm.substring(index)) 1469 : nm.substring(index); 1470 result = Integer.valueOf(constant, radix); 1471 } 1472 return result; 1473 } 1474 1475 /** 1476 * Compares two {@code Integer} objects numerically. 1477 * 1478 * @param anotherInteger the {@code Integer} to be compared. 1479 * @return the value {@code 0} if this {@code Integer} is 1480 * equal to the argument {@code Integer}; a value less than 1481 * {@code 0} if this {@code Integer} is numerically less 1482 * than the argument {@code Integer}; and a value greater 1483 * than {@code 0} if this {@code Integer} is numerically 1484 * greater than the argument {@code Integer} (signed 1485 * comparison). 1486 * @since 1.2 1487 */ 1488 public int compareTo(Integer anotherInteger) { 1489 return compare(this.value, anotherInteger.value); 1490 } 1491 1492 /** 1493 * Compares two {@code int} values numerically. 1494 * The value returned is identical to what would be returned by: 1495 * <pre> 1496 * Integer.valueOf(x).compareTo(Integer.valueOf(y)) 1497 * </pre> 1498 * 1499 * @param x the first {@code int} to compare 1500 * @param y the second {@code int} to compare 1501 * @return the value {@code 0} if {@code x == y}; 1502 * a value less than {@code 0} if {@code x < y}; and 1503 * a value greater than {@code 0} if {@code x > y} 1504 * @since 1.7 1505 */ 1506 public static int compare(int x, int y) { 1507 return (x < y) ? -1 : ((x == y) ? 0 : 1); 1508 } 1509 1510 /** 1511 * Compares two {@code int} values numerically treating the values 1512 * as unsigned. 1513 * 1514 * @param x the first {@code int} to compare 1515 * @param y the second {@code int} to compare 1516 * @return the value {@code 0} if {@code x == y}; a value less 1517 * than {@code 0} if {@code x < y} as unsigned values; and 1518 * a value greater than {@code 0} if {@code x > y} as 1519 * unsigned values 1520 * @since 1.8 1521 */ 1522 public static int compareUnsigned(int x, int y) { 1523 return compare(x + MIN_VALUE, y + MIN_VALUE); 1524 } 1525 1526 /** 1527 * Converts the argument to a {@code long} by an unsigned 1528 * conversion. In an unsigned conversion to a {@code long}, the 1529 * high-order 32 bits of the {@code long} are zero and the 1530 * low-order 32 bits are equal to the bits of the integer 1531 * argument. 1532 * 1533 * Consequently, zero and positive {@code int} values are mapped 1534 * to a numerically equal {@code long} value and negative {@code 1535 * int} values are mapped to a {@code long} value equal to the 1536 * input plus 2<sup>32</sup>. 1537 * 1538 * @param x the value to convert to an unsigned {@code long} 1539 * @return the argument converted to {@code long} by an unsigned 1540 * conversion 1541 * @since 1.8 1542 */ 1543 public static long toUnsignedLong(int x) { 1544 return ((long) x) & 0xffffffffL; 1545 } 1546 1547 /** 1548 * Returns the unsigned quotient of dividing the first argument by 1549 * the second where each argument and the result is interpreted as 1550 * an unsigned value. 1551 * 1552 * <p>Note that in two's complement arithmetic, the three other 1553 * basic arithmetic operations of add, subtract, and multiply are 1554 * bit-wise identical if the two operands are regarded as both 1555 * being signed or both being unsigned. Therefore separate {@code 1556 * addUnsigned}, etc. methods are not provided. 1557 * 1558 * @param dividend the value to be divided 1559 * @param divisor the value doing the dividing 1560 * @return the unsigned quotient of the first argument divided by 1561 * the second argument 1562 * @see #remainderUnsigned 1563 * @since 1.8 1564 */ 1565 public static int divideUnsigned(int dividend, int divisor) { 1566 // In lieu of tricky code, for now just use long arithmetic. 1567 return (int)(toUnsignedLong(dividend) / toUnsignedLong(divisor)); 1568 } 1569 1570 /** 1571 * Returns the unsigned remainder from dividing the first argument 1572 * by the second where each argument and the result is interpreted 1573 * as an unsigned value. 1574 * 1575 * @param dividend the value to be divided 1576 * @param divisor the value doing the dividing 1577 * @return the unsigned remainder of the first argument divided by 1578 * the second argument 1579 * @see #divideUnsigned 1580 * @since 1.8 1581 */ 1582 public static int remainderUnsigned(int dividend, int divisor) { 1583 // In lieu of tricky code, for now just use long arithmetic. 1584 return (int)(toUnsignedLong(dividend) % toUnsignedLong(divisor)); 1585 } 1586 1587 1588 // Bit twiddling 1589 1590 /** 1591 * The number of bits used to represent an {@code int} value in two's 1592 * complement binary form. 1593 * 1594 * @since 1.5 1595 */ 1596 @Native public static final int SIZE = 32; 1597 1598 /** 1599 * The number of bytes used to represent a {@code int} value in two's 1600 * complement binary form. 1601 * 1602 * @since 1.8 1603 */ 1604 public static final int BYTES = SIZE / Byte.SIZE; 1605 1606 /** 1607 * Returns an {@code int} value with at most a single one-bit, in the 1608 * position of the highest-order ("leftmost") one-bit in the specified 1609 * {@code int} value. Returns zero if the specified value has no 1610 * one-bits in its two's complement binary representation, that is, if it 1611 * is equal to zero. 1612 * 1613 * @param i the value whose highest one bit is to be computed 1614 * @return an {@code int} value with a single one-bit, in the position 1615 * of the highest-order one-bit in the specified value, or zero if 1616 * the specified value is itself equal to zero. 1617 * @since 1.5 1618 */ 1619 public static int highestOneBit(int i) { 1620 // HD, Figure 3-1 1621 i |= (i >> 1); 1622 i |= (i >> 2); 1623 i |= (i >> 4); 1624 i |= (i >> 8); 1625 i |= (i >> 16); 1626 return i - (i >>> 1); 1627 } 1628 1629 /** 1630 * Returns an {@code int} value with at most a single one-bit, in the 1631 * position of the lowest-order ("rightmost") one-bit in the specified 1632 * {@code int} value. Returns zero if the specified value has no 1633 * one-bits in its two's complement binary representation, that is, if it 1634 * is equal to zero. 1635 * 1636 * @param i the value whose lowest one bit is to be computed 1637 * @return an {@code int} value with a single one-bit, in the position 1638 * of the lowest-order one-bit in the specified value, or zero if 1639 * the specified value is itself equal to zero. 1640 * @since 1.5 1641 */ 1642 public static int lowestOneBit(int i) { 1643 // HD, Section 2-1 1644 return i & -i; 1645 } 1646 1647 /** 1648 * Returns the number of zero bits preceding the highest-order 1649 * ("leftmost") one-bit in the two's complement binary representation 1650 * of the specified {@code int} value. Returns 32 if the 1651 * specified value has no one-bits in its two's complement representation, 1652 * in other words if it is equal to zero. 1653 * 1654 * <p>Note that this method is closely related to the logarithm base 2. 1655 * For all positive {@code int} values x: 1656 * <ul> 1657 * <li>floor(log<sub>2</sub>(x)) = {@code 31 - numberOfLeadingZeros(x)} 1658 * <li>ceil(log<sub>2</sub>(x)) = {@code 32 - numberOfLeadingZeros(x - 1)} 1659 * </ul> 1660 * 1661 * @param i the value whose number of leading zeros is to be computed 1662 * @return the number of zero bits preceding the highest-order 1663 * ("leftmost") one-bit in the two's complement binary representation 1664 * of the specified {@code int} value, or 32 if the value 1665 * is equal to zero. 1666 * @since 1.5 1667 */ 1668 @HotSpotIntrinsicCandidate 1669 public static int numberOfLeadingZeros(int i) { 1670 // HD, Figure 5-6 1671 if (i == 0) 1672 return 32; 1673 int n = 1; 1674 if (i >>> 16 == 0) { n += 16; i <<= 16; } 1675 if (i >>> 24 == 0) { n += 8; i <<= 8; } 1676 if (i >>> 28 == 0) { n += 4; i <<= 4; } 1677 if (i >>> 30 == 0) { n += 2; i <<= 2; } 1678 n -= i >>> 31; 1679 return n; 1680 } 1681 1682 /** 1683 * Returns the number of zero bits following the lowest-order ("rightmost") 1684 * one-bit in the two's complement binary representation of the specified 1685 * {@code int} value. Returns 32 if the specified value has no 1686 * one-bits in its two's complement representation, in other words if it is 1687 * equal to zero. 1688 * 1689 * @param i the value whose number of trailing zeros is to be computed 1690 * @return the number of zero bits following the lowest-order ("rightmost") 1691 * one-bit in the two's complement binary representation of the 1692 * specified {@code int} value, or 32 if the value is equal 1693 * to zero. 1694 * @since 1.5 1695 */ 1696 @HotSpotIntrinsicCandidate 1697 public static int numberOfTrailingZeros(int i) { 1698 // HD, Figure 5-14 1699 int y; 1700 if (i == 0) return 32; 1701 int n = 31; 1702 y = i <<16; if (y != 0) { n = n -16; i = y; } 1703 y = i << 8; if (y != 0) { n = n - 8; i = y; } 1704 y = i << 4; if (y != 0) { n = n - 4; i = y; } 1705 y = i << 2; if (y != 0) { n = n - 2; i = y; } 1706 return n - ((i << 1) >>> 31); 1707 } 1708 1709 /** 1710 * Returns the number of one-bits in the two's complement binary 1711 * representation of the specified {@code int} value. This function is 1712 * sometimes referred to as the <i>population count</i>. 1713 * 1714 * @param i the value whose bits are to be counted 1715 * @return the number of one-bits in the two's complement binary 1716 * representation of the specified {@code int} value. 1717 * @since 1.5 1718 */ 1719 @HotSpotIntrinsicCandidate 1720 public static int bitCount(int i) { 1721 // HD, Figure 5-2 1722 i = i - ((i >>> 1) & 0x55555555); 1723 i = (i & 0x33333333) + ((i >>> 2) & 0x33333333); 1724 i = (i + (i >>> 4)) & 0x0f0f0f0f; 1725 i = i + (i >>> 8); 1726 i = i + (i >>> 16); 1727 return i & 0x3f; 1728 } 1729 1730 /** 1731 * Returns the value obtained by rotating the two's complement binary 1732 * representation of the specified {@code int} value left by the 1733 * specified number of bits. (Bits shifted out of the left hand, or 1734 * high-order, side reenter on the right, or low-order.) 1735 * 1736 * <p>Note that left rotation with a negative distance is equivalent to 1737 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val, 1738 * distance)}. Note also that rotation by any multiple of 32 is a 1739 * no-op, so all but the last five bits of the rotation distance can be 1740 * ignored, even if the distance is negative: {@code rotateLeft(val, 1741 * distance) == rotateLeft(val, distance & 0x1F)}. 1742 * 1743 * @param i the value whose bits are to be rotated left 1744 * @param distance the number of bit positions to rotate left 1745 * @return the value obtained by rotating the two's complement binary 1746 * representation of the specified {@code int} value left by the 1747 * specified number of bits. 1748 * @since 1.5 1749 */ 1750 public static int rotateLeft(int i, int distance) { 1751 return (i << distance) | (i >>> -distance); 1752 } 1753 1754 /** 1755 * Returns the value obtained by rotating the two's complement binary 1756 * representation of the specified {@code int} value right by the 1757 * specified number of bits. (Bits shifted out of the right hand, or 1758 * low-order, side reenter on the left, or high-order.) 1759 * 1760 * <p>Note that right rotation with a negative distance is equivalent to 1761 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val, 1762 * distance)}. Note also that rotation by any multiple of 32 is a 1763 * no-op, so all but the last five bits of the rotation distance can be 1764 * ignored, even if the distance is negative: {@code rotateRight(val, 1765 * distance) == rotateRight(val, distance & 0x1F)}. 1766 * 1767 * @param i the value whose bits are to be rotated right 1768 * @param distance the number of bit positions to rotate right 1769 * @return the value obtained by rotating the two's complement binary 1770 * representation of the specified {@code int} value right by the 1771 * specified number of bits. 1772 * @since 1.5 1773 */ 1774 public static int rotateRight(int i, int distance) { 1775 return (i >>> distance) | (i << -distance); 1776 } 1777 1778 /** 1779 * Returns the value obtained by reversing the order of the bits in the 1780 * two's complement binary representation of the specified {@code int} 1781 * value. 1782 * 1783 * @param i the value to be reversed 1784 * @return the value obtained by reversing order of the bits in the 1785 * specified {@code int} value. 1786 * @since 1.5 1787 */ 1788 public static int reverse(int i) { 1789 // HD, Figure 7-1 1790 i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555; 1791 i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333; 1792 i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f; 1793 i = (i << 24) | ((i & 0xff00) << 8) | 1794 ((i >>> 8) & 0xff00) | (i >>> 24); 1795 return i; 1796 } 1797 1798 /** 1799 * Returns the signum function of the specified {@code int} value. (The 1800 * return value is -1 if the specified value is negative; 0 if the 1801 * specified value is zero; and 1 if the specified value is positive.) 1802 * 1803 * @param i the value whose signum is to be computed 1804 * @return the signum function of the specified {@code int} value. 1805 * @since 1.5 1806 */ 1807 public static int signum(int i) { 1808 // HD, Section 2-7 1809 return (i >> 31) | (-i >>> 31); 1810 } 1811 1812 /** 1813 * Returns the value obtained by reversing the order of the bytes in the 1814 * two's complement representation of the specified {@code int} value. 1815 * 1816 * @param i the value whose bytes are to be reversed 1817 * @return the value obtained by reversing the bytes in the specified 1818 * {@code int} value. 1819 * @since 1.5 1820 */ 1821 @HotSpotIntrinsicCandidate 1822 public static int reverseBytes(int i) { 1823 return ((i >>> 24) ) | 1824 ((i >> 8) & 0xFF00) | 1825 ((i << 8) & 0xFF0000) | 1826 ((i << 24)); 1827 } 1828 1829 /** 1830 * Adds two integers together as per the + operator. 1831 * 1832 * @param a the first operand 1833 * @param b the second operand 1834 * @return the sum of {@code a} and {@code b} 1835 * @see java.util.function.BinaryOperator 1836 * @since 1.8 1837 */ 1838 public static int sum(int a, int b) { 1839 return a + b; 1840 } 1841 1842 /** 1843 * Returns the greater of two {@code int} values 1844 * as if by calling {@link Math#max(int, int) Math.max}. 1845 * 1846 * @param a the first operand 1847 * @param b the second operand 1848 * @return the greater of {@code a} and {@code b} 1849 * @see java.util.function.BinaryOperator 1850 * @since 1.8 1851 */ 1852 public static int max(int a, int b) { 1853 return Math.max(a, b); 1854 } 1855 1856 /** 1857 * Returns the smaller of two {@code int} values 1858 * as if by calling {@link Math#min(int, int) Math.min}. 1859 * 1860 * @param a the first operand 1861 * @param b the second operand 1862 * @return the smaller of {@code a} and {@code b} 1863 * @see java.util.function.BinaryOperator 1864 * @since 1.8 1865 */ 1866 public static int min(int a, int b) { 1867 return Math.min(a, b); 1868 } 1869 1870 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 1871 @Native private static final long serialVersionUID = 1360826667806852920L; 1872 }