001/* Integer.java -- object wrapper for int 002 Copyright (C) 1998, 1999, 2001, 2002, 2004, 2005 003 Free Software Foundation, Inc. 004 005This file is part of GNU Classpath. 006 007GNU Classpath is free software; you can redistribute it and/or modify 008it under the terms of the GNU General Public License as published by 009the Free Software Foundation; either version 2, or (at your option) 010any later version. 011 012GNU Classpath is distributed in the hope that it will be useful, but 013WITHOUT ANY WARRANTY; without even the implied warranty of 014MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 015General Public License for more details. 016 017You should have received a copy of the GNU General Public License 018along with GNU Classpath; see the file COPYING. If not, write to the 019Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02002110-1301 USA. 021 022Linking this library statically or dynamically with other modules is 023making a combined work based on this library. Thus, the terms and 024conditions of the GNU General Public License cover the whole 025combination. 026 027As a special exception, the copyright holders of this library give you 028permission to link this library with independent modules to produce an 029executable, regardless of the license terms of these independent 030modules, and to copy and distribute the resulting executable under 031terms of your choice, provided that you also meet, for each linked 032independent module, the terms and conditions of the license of that 033module. An independent module is a module which is not derived from 034or based on this library. If you modify this library, you may extend 035this exception to your version of the library, but you are not 036obligated to do so. If you do not wish to do so, delete this 037exception statement from your version. */ 038 039 040package java.lang; 041 042/** 043 * Instances of class <code>Integer</code> represent primitive 044 * <code>int</code> values. 045 * 046 * Additionally, this class provides various helper functions and variables 047 * related to ints. 048 * 049 * @author Paul Fisher 050 * @author John Keiser 051 * @author Warren Levy 052 * @author Eric Blake (ebb9@email.byu.edu) 053 * @author Tom Tromey (tromey@redhat.com) 054 * @author Andrew John Hughes (gnu_andrew@member.fsf.org) 055 * @author Ian Rogers 056 * @since 1.0 057 * @status updated to 1.5 058 */ 059public final class Integer extends Number implements Comparable<Integer> 060{ 061 /** 062 * Compatible with JDK 1.0.2+. 063 */ 064 private static final long serialVersionUID = 1360826667806852920L; 065 066 /** 067 * The minimum value an <code>int</code> can represent is -2147483648 (or 068 * -2<sup>31</sup>). 069 */ 070 public static final int MIN_VALUE = 0x80000000; 071 072 /** 073 * The maximum value an <code>int</code> can represent is 2147483647 (or 074 * 2<sup>31</sup> - 1). 075 */ 076 public static final int MAX_VALUE = 0x7fffffff; 077 078 /** 079 * The primitive type <code>int</code> is represented by this 080 * <code>Class</code> object. 081 * @since 1.1 082 */ 083 public static final Class<Integer> TYPE = (Class<Integer>) VMClassLoader.getPrimitiveClass('I'); 084 085 /** 086 * The number of bits needed to represent an <code>int</code>. 087 * @since 1.5 088 */ 089 public static final int SIZE = 32; 090 091 // This caches some Integer values, and is used by boxing 092 // conversions via valueOf(). We must cache at least -128..127; 093 // these constants control how much we actually cache. 094 private static final int MIN_CACHE = -128; 095 private static final int MAX_CACHE = 127; 096 private static final Integer[] intCache = new Integer[MAX_CACHE - MIN_CACHE + 1]; 097 static 098 { 099 for (int i=MIN_CACHE; i <= MAX_CACHE; i++) 100 intCache[i - MIN_CACHE] = new Integer(i); 101 } 102 103 /** 104 * The immutable value of this Integer. 105 * 106 * @serial the wrapped int 107 */ 108 private final int value; 109 110 /** 111 * Create an <code>Integer</code> object representing the value of the 112 * <code>int</code> argument. 113 * 114 * @param value the value to use 115 */ 116 public Integer(int value) 117 { 118 this.value = value; 119 } 120 121 /** 122 * Create an <code>Integer</code> object representing the value of the 123 * argument after conversion to an <code>int</code>. 124 * 125 * @param s the string to convert 126 * @throws NumberFormatException if the String does not contain an int 127 * @see #valueOf(String) 128 */ 129 public Integer(String s) 130 { 131 value = parseInt(s, 10, false); 132 } 133 134 /** 135 * Return the size of a string large enough to hold the given number 136 * 137 * @param num the number we want the string length for (must be positive) 138 * @param radix the radix (base) that will be used for the string 139 * @return a size sufficient for a string of num 140 */ 141 private static int stringSize(int num, int radix) { 142 int exp; 143 if (radix < 4) 144 { 145 exp = 1; 146 } 147 else if (radix < 8) 148 { 149 exp = 2; 150 } 151 else if (radix < 16) 152 { 153 exp = 3; 154 } 155 else if (radix < 32) 156 { 157 exp = 4; 158 } 159 else 160 { 161 exp = 5; 162 } 163 int size=0; 164 do 165 { 166 num >>>= exp; 167 size++; 168 } 169 while(num != 0); 170 return size; 171 } 172 173 /** 174 * Converts the <code>int</code> to a <code>String</code> using 175 * the specified radix (base). If the radix exceeds 176 * <code>Character.MIN_RADIX</code> or <code>Character.MAX_RADIX</code>, 10 177 * is used instead. If the result is negative, the leading character is 178 * '-' ('\\u002D'). The remaining characters come from 179 * <code>Character.forDigit(digit, radix)</code> ('0'-'9','a'-'z'). 180 * 181 * @param num the <code>int</code> to convert to <code>String</code> 182 * @param radix the radix (base) to use in the conversion 183 * @return the <code>String</code> representation of the argument 184 */ 185 public static String toString(int num, int radix) 186 { 187 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX) 188 radix = 10; 189 190 // Is the value negative? 191 boolean isNeg = num < 0; 192 193 // Is the string a single character? 194 if (!isNeg && num < radix) 195 return new String(digits, num, 1, true); 196 197 // Compute string size and allocate buffer 198 // account for a leading '-' if the value is negative 199 int size; 200 int i; 201 char[] buffer; 202 if (isNeg) 203 { 204 num = -num; 205 206 // When the value is MIN_VALUE, it overflows when made positive 207 if (num < 0) 208 { 209 i = size = stringSize(MAX_VALUE, radix) + 2; 210 buffer = new char[size]; 211 buffer[--i] = digits[(int) (-(num + radix) % radix)]; 212 num = -(num / radix); 213 } 214 else 215 { 216 i = size = stringSize(num, radix) + 1; 217 buffer = new char[size]; 218 } 219 } 220 else 221 { 222 i = size = stringSize(num, radix); 223 buffer = new char[size]; 224 } 225 226 do 227 { 228 buffer[--i] = digits[num % radix]; 229 num /= radix; 230 } 231 while (num > 0); 232 233 if (isNeg) 234 buffer[--i] = '-'; 235 236 // Package constructor avoids an array copy. 237 return new String(buffer, i, size - i, true); 238 } 239 240 /** 241 * Converts the <code>int</code> to a <code>String</code> assuming it is 242 * unsigned in base 16. 243 * 244 * @param i the <code>int</code> to convert to <code>String</code> 245 * @return the <code>String</code> representation of the argument 246 */ 247 public static String toHexString(int i) 248 { 249 return toUnsignedString(i, 4); 250 } 251 252 /** 253 * Converts the <code>int</code> to a <code>String</code> assuming it is 254 * unsigned in base 8. 255 * 256 * @param i the <code>int</code> to convert to <code>String</code> 257 * @return the <code>String</code> representation of the argument 258 */ 259 public static String toOctalString(int i) 260 { 261 return toUnsignedString(i, 3); 262 } 263 264 /** 265 * Converts the <code>int</code> to a <code>String</code> assuming it is 266 * unsigned in base 2. 267 * 268 * @param i the <code>int</code> to convert to <code>String</code> 269 * @return the <code>String</code> representation of the argument 270 */ 271 public static String toBinaryString(int i) 272 { 273 return toUnsignedString(i, 1); 274 } 275 276 /** 277 * Converts the <code>int</code> to a <code>String</code> and assumes 278 * a radix of 10. 279 * 280 * @param i the <code>int</code> to convert to <code>String</code> 281 * @return the <code>String</code> representation of the argument 282 * @see #toString(int, int) 283 */ 284 public static String toString(int i) 285 { 286 // This is tricky: in libgcj, String.valueOf(int) is a fast native 287 // implementation. In Classpath it just calls back to 288 // Integer.toString(int, int). 289 return String.valueOf(i); 290 } 291 292 /** 293 * Converts the specified <code>String</code> into an <code>int</code> 294 * using the specified radix (base). The string must not be <code>null</code> 295 * or empty. It may begin with an optional '-', which will negate the answer, 296 * provided that there are also valid digits. Each digit is parsed as if by 297 * <code>Character.digit(d, radix)</code>, and must be in the range 298 * <code>0</code> to <code>radix - 1</code>. Finally, the result must be 299 * within <code>MIN_VALUE</code> to <code>MAX_VALUE</code>, inclusive. 300 * Unlike Double.parseDouble, you may not have a leading '+'. 301 * 302 * @param str the <code>String</code> to convert 303 * @param radix the radix (base) to use in the conversion 304 * @return the <code>String</code> argument converted to <code>int</code> 305 * @throws NumberFormatException if <code>s</code> cannot be parsed as an 306 * <code>int</code> 307 */ 308 public static int parseInt(String str, int radix) 309 { 310 return parseInt(str, radix, false); 311 } 312 313 /** 314 * Converts the specified <code>String</code> into an <code>int</code>. 315 * This function assumes a radix of 10. 316 * 317 * @param s the <code>String</code> to convert 318 * @return the <code>int</code> value of <code>s</code> 319 * @throws NumberFormatException if <code>s</code> cannot be parsed as an 320 * <code>int</code> 321 * @see #parseInt(String, int) 322 */ 323 public static int parseInt(String s) 324 { 325 return parseInt(s, 10, false); 326 } 327 328 /** 329 * Creates a new <code>Integer</code> object using the <code>String</code> 330 * and specified radix (base). 331 * 332 * @param s the <code>String</code> to convert 333 * @param radix the radix (base) to convert with 334 * @return the new <code>Integer</code> 335 * @throws NumberFormatException if <code>s</code> cannot be parsed as an 336 * <code>int</code> 337 * @see #parseInt(String, int) 338 */ 339 public static Integer valueOf(String s, int radix) 340 { 341 return valueOf(parseInt(s, radix, false)); 342 } 343 344 /** 345 * Creates a new <code>Integer</code> object using the <code>String</code>, 346 * assuming a radix of 10. 347 * 348 * @param s the <code>String</code> to convert 349 * @return the new <code>Integer</code> 350 * @throws NumberFormatException if <code>s</code> cannot be parsed as an 351 * <code>int</code> 352 * @see #Integer(String) 353 * @see #parseInt(String) 354 */ 355 public static Integer valueOf(String s) 356 { 357 return valueOf(parseInt(s, 10, false)); 358 } 359 360 /** 361 * Returns an <code>Integer</code> object wrapping the value. 362 * In contrast to the <code>Integer</code> constructor, this method 363 * will cache some values. It is used by boxing conversion. 364 * 365 * @param val the value to wrap 366 * @return the <code>Integer</code> 367 */ 368 public static Integer valueOf(int val) 369 { 370 if (val < MIN_CACHE || val > MAX_CACHE) 371 return new Integer(val); 372 else 373 return intCache[val - MIN_CACHE]; 374 } 375 376 /** 377 * Return the value of this <code>Integer</code> as a <code>byte</code>. 378 * 379 * @return the byte value 380 */ 381 public byte byteValue() 382 { 383 return (byte) value; 384 } 385 386 /** 387 * Return the value of this <code>Integer</code> as a <code>short</code>. 388 * 389 * @return the short value 390 */ 391 public short shortValue() 392 { 393 return (short) value; 394 } 395 396 /** 397 * Return the value of this <code>Integer</code>. 398 * @return the int value 399 */ 400 public int intValue() 401 { 402 return value; 403 } 404 405 /** 406 * Return the value of this <code>Integer</code> as a <code>long</code>. 407 * 408 * @return the long value 409 */ 410 public long longValue() 411 { 412 return value; 413 } 414 415 /** 416 * Return the value of this <code>Integer</code> as a <code>float</code>. 417 * 418 * @return the float value 419 */ 420 public float floatValue() 421 { 422 return value; 423 } 424 425 /** 426 * Return the value of this <code>Integer</code> as a <code>double</code>. 427 * 428 * @return the double value 429 */ 430 public double doubleValue() 431 { 432 return value; 433 } 434 435 /** 436 * Converts the <code>Integer</code> value to a <code>String</code> and 437 * assumes a radix of 10. 438 * 439 * @return the <code>String</code> representation 440 */ 441 public String toString() 442 { 443 return String.valueOf(value); 444 } 445 446 /** 447 * Return a hashcode representing this Object. <code>Integer</code>'s hash 448 * code is simply its value. 449 * 450 * @return this Object's hash code 451 */ 452 public int hashCode() 453 { 454 return value; 455 } 456 457 /** 458 * Returns <code>true</code> if <code>obj</code> is an instance of 459 * <code>Integer</code> and represents the same int value. 460 * 461 * @param obj the object to compare 462 * @return whether these Objects are semantically equal 463 */ 464 public boolean equals(Object obj) 465 { 466 return obj instanceof Integer && value == ((Integer) obj).value; 467 } 468 469 /** 470 * Get the specified system property as an <code>Integer</code>. The 471 * <code>decode()</code> method will be used to interpret the value of 472 * the property. 473 * 474 * @param nm the name of the system property 475 * @return the system property as an <code>Integer</code>, or null if the 476 * property is not found or cannot be decoded 477 * @throws SecurityException if accessing the system property is forbidden 478 * @see System#getProperty(String) 479 * @see #decode(String) 480 */ 481 public static Integer getInteger(String nm) 482 { 483 return getInteger(nm, null); 484 } 485 486 /** 487 * Get the specified system property as an <code>Integer</code>, or use a 488 * default <code>int</code> value if the property is not found or is not 489 * decodable. The <code>decode()</code> method will be used to interpret 490 * the value of the property. 491 * 492 * @param nm the name of the system property 493 * @param val the default value 494 * @return the value of the system property, or the default 495 * @throws SecurityException if accessing the system property is forbidden 496 * @see System#getProperty(String) 497 * @see #decode(String) 498 */ 499 public static Integer getInteger(String nm, int val) 500 { 501 Integer result = getInteger(nm, null); 502 return result == null ? valueOf(val) : result; 503 } 504 505 /** 506 * Get the specified system property as an <code>Integer</code>, or use a 507 * default <code>Integer</code> value if the property is not found or is 508 * not decodable. The <code>decode()</code> method will be used to 509 * interpret the value of the property. 510 * 511 * @param nm the name of the system property 512 * @param def the default value 513 * @return the value of the system property, or the default 514 * @throws SecurityException if accessing the system property is forbidden 515 * @see System#getProperty(String) 516 * @see #decode(String) 517 */ 518 public static Integer getInteger(String nm, Integer def) 519 { 520 if (nm == null || "".equals(nm)) 521 return def; 522 nm = System.getProperty(nm); 523 if (nm == null) 524 return def; 525 try 526 { 527 return decode(nm); 528 } 529 catch (NumberFormatException e) 530 { 531 return def; 532 } 533 } 534 535 /** 536 * Convert the specified <code>String</code> into an <code>Integer</code>. 537 * The <code>String</code> may represent decimal, hexadecimal, or 538 * octal numbers. 539 * 540 * <p>The extended BNF grammar is as follows:<br> 541 * <pre> 542 * <em>DecodableString</em>: 543 * ( [ <code>-</code> ] <em>DecimalNumber</em> ) 544 * | ( [ <code>-</code> ] ( <code>0x</code> | <code>0X</code> 545 * | <code>#</code> ) <em>HexDigit</em> { <em>HexDigit</em> } ) 546 * | ( [ <code>-</code> ] <code>0</code> { <em>OctalDigit</em> } ) 547 * <em>DecimalNumber</em>: 548 * <em>DecimalDigit except '0'</em> { <em>DecimalDigit</em> } 549 * <em>DecimalDigit</em>: 550 * <em>Character.digit(d, 10) has value 0 to 9</em> 551 * <em>OctalDigit</em>: 552 * <em>Character.digit(d, 8) has value 0 to 7</em> 553 * <em>DecimalDigit</em>: 554 * <em>Character.digit(d, 16) has value 0 to 15</em> 555 * </pre> 556 * Finally, the value must be in the range <code>MIN_VALUE</code> to 557 * <code>MAX_VALUE</code>, or an exception is thrown. 558 * 559 * @param str the <code>String</code> to interpret 560 * @return the value of the String as an <code>Integer</code> 561 * @throws NumberFormatException if <code>s</code> cannot be parsed as a 562 * <code>int</code> 563 * @throws NullPointerException if <code>s</code> is null 564 * @since 1.2 565 */ 566 public static Integer decode(String str) 567 { 568 return valueOf(parseInt(str, 10, true)); 569 } 570 571 /** 572 * Compare two Integers numerically by comparing their <code>int</code> 573 * values. The result is positive if the first is greater, negative if the 574 * second is greater, and 0 if the two are equal. 575 * 576 * @param i the Integer to compare 577 * @return the comparison 578 * @since 1.2 579 */ 580 public int compareTo(Integer i) 581 { 582 if (value == i.value) 583 return 0; 584 // Returns just -1 or 1 on inequality; doing math might overflow. 585 return value > i.value ? 1 : -1; 586 } 587 588 /** 589 * Return the number of bits set in x. 590 * @param x value to examine 591 * @since 1.5 592 */ 593 public static int bitCount(int x) 594 { 595 // Successively collapse alternating bit groups into a sum. 596 x = ((x >> 1) & 0x55555555) + (x & 0x55555555); 597 x = ((x >> 2) & 0x33333333) + (x & 0x33333333); 598 x = ((x >> 4) & 0x0f0f0f0f) + (x & 0x0f0f0f0f); 599 x = ((x >> 8) & 0x00ff00ff) + (x & 0x00ff00ff); 600 return ((x >> 16) & 0x0000ffff) + (x & 0x0000ffff); 601 } 602 603 /** 604 * Rotate x to the left by distance bits. 605 * @param x the value to rotate 606 * @param distance the number of bits by which to rotate 607 * @since 1.5 608 */ 609 public static int rotateLeft(int x, int distance) 610 { 611 // This trick works because the shift operators implicitly mask 612 // the shift count. 613 return (x << distance) | (x >>> - distance); 614 } 615 616 /** 617 * Rotate x to the right by distance bits. 618 * @param x the value to rotate 619 * @param distance the number of bits by which to rotate 620 * @since 1.5 621 */ 622 public static int rotateRight(int x, int distance) 623 { 624 // This trick works because the shift operators implicitly mask 625 // the shift count. 626 return (x << - distance) | (x >>> distance); 627 } 628 629 /** 630 * Find the highest set bit in value, and return a new value 631 * with only that bit set. 632 * @param value the value to examine 633 * @since 1.5 634 */ 635 public static int highestOneBit(int value) 636 { 637 value |= value >>> 1; 638 value |= value >>> 2; 639 value |= value >>> 4; 640 value |= value >>> 8; 641 value |= value >>> 16; 642 return value ^ (value >>> 1); 643 } 644 645 /** 646 * Return the number of leading zeros in value. 647 * @param value the value to examine 648 * @since 1.5 649 */ 650 public static int numberOfLeadingZeros(int value) 651 { 652 value |= value >>> 1; 653 value |= value >>> 2; 654 value |= value >>> 4; 655 value |= value >>> 8; 656 value |= value >>> 16; 657 return bitCount(~value); 658 } 659 660 /** 661 * Find the lowest set bit in value, and return a new value 662 * with only that bit set. 663 * @param value the value to examine 664 * @since 1.5 665 */ 666 public static int lowestOneBit(int value) 667 { 668 // Classic assembly trick. 669 return value & - value; 670 } 671 672 /** 673 * Find the number of trailing zeros in value. 674 * @param value the value to examine 675 * @since 1.5 676 */ 677 public static int numberOfTrailingZeros(int value) 678 { 679 return bitCount((value & -value) - 1); 680 } 681 682 /** 683 * Return 1 if x is positive, -1 if it is negative, and 0 if it is 684 * zero. 685 * @param x the value to examine 686 * @since 1.5 687 */ 688 public static int signum(int x) 689 { 690 return (x >> 31) | (-x >>> 31); 691 692 // The LHS propagates the sign bit through every bit in the word; 693 // if X < 0, every bit is set to 1, else 0. if X > 0, the RHS 694 // negates x and shifts the resulting 1 in the sign bit to the 695 // LSB, leaving every other bit 0. 696 697 // Hacker's Delight, Section 2-7 698 } 699 700 /** 701 * Reverse the bytes in val. 702 * @since 1.5 703 */ 704 public static int reverseBytes(int val) 705 { 706 return ( ((val >> 24) & 0xff) 707 | ((val >> 8) & 0xff00) 708 | ((val << 8) & 0xff0000) 709 | ((val << 24) & 0xff000000)); 710 } 711 712 /** 713 * Reverse the bits in val. 714 * @since 1.5 715 */ 716 public static int reverse(int val) 717 { 718 // Successively swap alternating bit groups. 719 val = ((val >> 1) & 0x55555555) + ((val << 1) & ~0x55555555); 720 val = ((val >> 2) & 0x33333333) + ((val << 2) & ~0x33333333); 721 val = ((val >> 4) & 0x0f0f0f0f) + ((val << 4) & ~0x0f0f0f0f); 722 val = ((val >> 8) & 0x00ff00ff) + ((val << 8) & ~0x00ff00ff); 723 return ((val >> 16) & 0x0000ffff) + ((val << 16) & ~0x0000ffff); 724 } 725 726 /** 727 * Helper for converting unsigned numbers to String. 728 * 729 * @param num the number 730 * @param exp log2(digit) (ie. 1, 3, or 4 for binary, oct, hex) 731 */ 732 // Package visible for use by Long. 733 static String toUnsignedString(int num, int exp) 734 { 735 // Compute string length 736 int size = 1; 737 int copy = num >>> exp; 738 while (copy != 0) 739 { 740 size++; 741 copy >>>= exp; 742 } 743 // Quick path for single character strings 744 if (size == 1) 745 return new String(digits, num, 1, true); 746 747 // Encode into buffer 748 int mask = (1 << exp) - 1; 749 char[] buffer = new char[size]; 750 int i = size; 751 do 752 { 753 buffer[--i] = digits[num & mask]; 754 num >>>= exp; 755 } 756 while (num != 0); 757 758 // Package constructor avoids an array copy. 759 return new String(buffer, i, size - i, true); 760 } 761 762 /** 763 * Helper for parsing ints, used by Integer, Short, and Byte. 764 * 765 * @param str the string to parse 766 * @param radix the radix to use, must be 10 if decode is true 767 * @param decode if called from decode 768 * @return the parsed int value 769 * @throws NumberFormatException if there is an error 770 * @throws NullPointerException if decode is true and str if null 771 * @see #parseInt(String, int) 772 * @see #decode(String) 773 * @see Byte#parseByte(String, int) 774 * @see Short#parseShort(String, int) 775 */ 776 static int parseInt(String str, int radix, boolean decode) 777 { 778 if (! decode && str == null) 779 throw new NumberFormatException(); 780 int index = 0; 781 int len = str.length(); 782 boolean isNeg = false; 783 if (len == 0) 784 throw new NumberFormatException("string length is null"); 785 int ch = str.charAt(index); 786 if (ch == '-') 787 { 788 if (len == 1) 789 throw new NumberFormatException("pure '-'"); 790 isNeg = true; 791 ch = str.charAt(++index); 792 } 793 else if (ch == '+') 794 { 795 if (len == 1) 796 throw new NumberFormatException("pure '+'"); 797 ch = str.charAt(++index); 798 } 799 if (decode) 800 { 801 if (ch == '0') 802 { 803 if (++index == len) 804 return 0; 805 if ((str.charAt(index) & ~('x' ^ 'X')) == 'X') 806 { 807 radix = 16; 808 index++; 809 } 810 else 811 radix = 8; 812 } 813 else if (ch == '#') 814 { 815 radix = 16; 816 index++; 817 } 818 } 819 if (index == len) 820 throw new NumberFormatException("non terminated number: " + str); 821 822 int max = MAX_VALUE / radix; 823 // We can't directly write `max = (MAX_VALUE + 1) / radix'. 824 // So instead we fake it. 825 if (isNeg && MAX_VALUE % radix == radix - 1) 826 ++max; 827 828 int val = 0; 829 while (index < len) 830 { 831 if (val < 0 || val > max) 832 throw new NumberFormatException("number overflow (pos=" + index + ") : " + str); 833 834 ch = Character.digit(str.charAt(index++), radix); 835 val = val * radix + ch; 836 if (ch < 0 || (val < 0 && (! isNeg || val != MIN_VALUE))) 837 throw new NumberFormatException("invalid character at position " + index + " in " + str); 838 } 839 return isNeg ? -val : val; 840 } 841}