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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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15 * accompanied this code).
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28 import org.apidesign.bck2brwsr.core.JavaScriptBody;
31 * The {@code Integer} class wraps a value of the primitive type
32 * {@code int} in an object. An object of type {@code Integer}
33 * contains a single field whose type is {@code int}.
35 * <p>In addition, this class provides several methods for converting
36 * an {@code int} to a {@code String} and a {@code String} to an
37 * {@code int}, as well as other constants and methods useful when
38 * dealing with an {@code int}.
40 * <p>Implementation note: The implementations of the "bit twiddling"
41 * methods (such as {@link #highestOneBit(int) highestOneBit} and
42 * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
43 * based on material from Henry S. Warren, Jr.'s <i>Hacker's
44 * Delight</i>, (Addison Wesley, 2002).
47 * @author Arthur van Hoff
49 * @author Joseph D. Darcy
52 public final class Integer extends Number implements Comparable<Integer> {
54 * A constant holding the minimum value an {@code int} can
55 * have, -2<sup>31</sup>.
57 public static final int MIN_VALUE = 0x80000000;
60 * A constant holding the maximum value an {@code int} can
61 * have, 2<sup>31</sup>-1.
63 public static final int MAX_VALUE = 0x7fffffff;
66 * The {@code Class} instance representing the primitive type
71 public static final Class<Integer> TYPE = (Class<Integer>) Class.getPrimitiveClass("int");
74 * All possible chars for representing a number as a String
76 final static char[] digits = {
77 '0' , '1' , '2' , '3' , '4' , '5' ,
78 '6' , '7' , '8' , '9' , 'a' , 'b' ,
79 'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
80 'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
81 'o' , 'p' , 'q' , 'r' , 's' , 't' ,
82 'u' , 'v' , 'w' , 'x' , 'y' , 'z'
86 * Returns a string representation of the first argument in the
87 * radix specified by the second argument.
89 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
90 * or larger than {@code Character.MAX_RADIX}, then the radix
91 * {@code 10} is used instead.
93 * <p>If the first argument is negative, the first element of the
94 * result is the ASCII minus character {@code '-'}
95 * (<code>'\u002D'</code>). If the first argument is not
96 * negative, no sign character appears in the result.
98 * <p>The remaining characters of the result represent the magnitude
99 * of the first argument. If the magnitude is zero, it is
100 * represented by a single zero character {@code '0'}
101 * (<code>'\u0030'</code>); otherwise, the first character of
102 * the representation of the magnitude will not be the zero
103 * character. The following ASCII characters are used as digits:
106 * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
109 * These are <code>'\u0030'</code> through
110 * <code>'\u0039'</code> and <code>'\u0061'</code> through
111 * <code>'\u007A'</code>. If {@code radix} is
112 * <var>N</var>, then the first <var>N</var> of these characters
113 * are used as radix-<var>N</var> digits in the order shown. Thus,
114 * the digits for hexadecimal (radix 16) are
115 * {@code 0123456789abcdef}. If uppercase letters are
116 * desired, the {@link java.lang.String#toUpperCase()} method may
117 * be called on the result:
120 * {@code Integer.toString(n, 16).toUpperCase()}
123 * @param i an integer to be converted to a string.
124 * @param radix the radix to use in the string representation.
125 * @return a string representation of the argument in the specified radix.
126 * @see java.lang.Character#MAX_RADIX
127 * @see java.lang.Character#MIN_RADIX
129 public static String toString(int i, int radix) {
131 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
134 /* Use the faster version */
139 char buf[] = new char[33];
140 boolean negative = (i < 0);
147 while (i <= -radix) {
148 buf[charPos--] = digits[-(i % radix)];
151 buf[charPos] = digits[-i];
154 buf[--charPos] = '-';
157 return new String(buf, charPos, (33 - charPos));
161 * Returns a string representation of the integer argument as an
162 * unsigned integer in base 16.
164 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
165 * if the argument is negative; otherwise, it is equal to the
166 * argument. This value is converted to a string of ASCII digits
167 * in hexadecimal (base 16) with no extra leading
168 * {@code 0}s. If the unsigned magnitude is zero, it is
169 * represented by a single zero character {@code '0'}
170 * (<code>'\u0030'</code>); otherwise, the first character of
171 * the representation of the unsigned magnitude will not be the
172 * zero character. The following characters are used as
173 * hexadecimal digits:
176 * {@code 0123456789abcdef}
179 * These are the characters <code>'\u0030'</code> through
180 * <code>'\u0039'</code> and <code>'\u0061'</code> through
181 * <code>'\u0066'</code>. If uppercase letters are
182 * desired, the {@link java.lang.String#toUpperCase()} method may
183 * be called on the result:
186 * {@code Integer.toHexString(n).toUpperCase()}
189 * @param i an integer to be converted to a string.
190 * @return the string representation of the unsigned integer value
191 * represented by the argument in hexadecimal (base 16).
194 public static String toHexString(int i) {
195 return toUnsignedString(i, 4);
199 * Returns a string representation of the integer argument as an
200 * unsigned integer in base 8.
202 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
203 * if the argument is negative; otherwise, it is equal to the
204 * argument. This value is converted to a string of ASCII digits
205 * in octal (base 8) with no extra leading {@code 0}s.
207 * <p>If the unsigned magnitude is zero, it is represented by a
208 * single zero character {@code '0'}
209 * (<code>'\u0030'</code>); otherwise, the first character of
210 * the representation of the unsigned magnitude will not be the
211 * zero character. The following characters are used as octal
218 * These are the characters <code>'\u0030'</code> through
219 * <code>'\u0037'</code>.
221 * @param i an integer to be converted to a string.
222 * @return the string representation of the unsigned integer value
223 * represented by the argument in octal (base 8).
226 public static String toOctalString(int i) {
227 return toUnsignedString(i, 3);
231 * Returns a string representation of the integer argument as an
232 * unsigned integer in base 2.
234 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
235 * if the argument is negative; otherwise it is equal to the
236 * argument. This value is converted to a string of ASCII digits
237 * in binary (base 2) with no extra leading {@code 0}s.
238 * If the unsigned magnitude is zero, it is represented by a
239 * single zero character {@code '0'}
240 * (<code>'\u0030'</code>); otherwise, the first character of
241 * the representation of the unsigned magnitude will not be the
242 * zero character. The characters {@code '0'}
243 * (<code>'\u0030'</code>) and {@code '1'}
244 * (<code>'\u0031'</code>) are used as binary digits.
246 * @param i an integer to be converted to a string.
247 * @return the string representation of the unsigned integer value
248 * represented by the argument in binary (base 2).
251 public static String toBinaryString(int i) {
252 return toUnsignedString(i, 1);
256 * Convert the integer to an unsigned number.
258 private static String toUnsignedString(int i, int shift) {
259 char[] buf = new char[32];
261 int radix = 1 << shift;
262 int mask = radix - 1;
264 buf[--charPos] = digits[i & mask];
268 return new String(buf, charPos, (32 - charPos));
272 final static char [] DigitTens = {
273 '0', '0', '0', '0', '0', '0', '0', '0', '0', '0',
274 '1', '1', '1', '1', '1', '1', '1', '1', '1', '1',
275 '2', '2', '2', '2', '2', '2', '2', '2', '2', '2',
276 '3', '3', '3', '3', '3', '3', '3', '3', '3', '3',
277 '4', '4', '4', '4', '4', '4', '4', '4', '4', '4',
278 '5', '5', '5', '5', '5', '5', '5', '5', '5', '5',
279 '6', '6', '6', '6', '6', '6', '6', '6', '6', '6',
280 '7', '7', '7', '7', '7', '7', '7', '7', '7', '7',
281 '8', '8', '8', '8', '8', '8', '8', '8', '8', '8',
282 '9', '9', '9', '9', '9', '9', '9', '9', '9', '9',
285 final static char [] DigitOnes = {
286 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
287 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
288 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
289 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
290 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
291 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
292 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
293 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
294 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
295 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
298 // I use the "invariant division by multiplication" trick to
299 // accelerate Integer.toString. In particular we want to
300 // avoid division by 10.
302 // The "trick" has roughly the same performance characteristics
303 // as the "classic" Integer.toString code on a non-JIT VM.
304 // The trick avoids .rem and .div calls but has a longer code
305 // path and is thus dominated by dispatch overhead. In the
306 // JIT case the dispatch overhead doesn't exist and the
307 // "trick" is considerably faster than the classic code.
309 // TODO-FIXME: convert (x * 52429) into the equiv shift-add
312 // RE: Division by Invariant Integers using Multiplication
313 // T Gralund, P Montgomery
318 * Returns a {@code String} object representing the
319 * specified integer. The argument is converted to signed decimal
320 * representation and returned as a string, exactly as if the
321 * argument and radix 10 were given as arguments to the {@link
322 * #toString(int, int)} method.
324 * @param i an integer to be converted.
325 * @return a string representation of the argument in base 10.
327 public static String toString(int i) {
328 if (i == Integer.MIN_VALUE)
329 return "-2147483648";
330 int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
331 char[] buf = new char[size];
332 getChars(i, size, buf);
333 return new String(0, size, buf);
337 * Places characters representing the integer i into the
338 * character array buf. The characters are placed into
339 * the buffer backwards starting with the least significant
340 * digit at the specified index (exclusive), and working
341 * backwards from there.
343 * Will fail if i == Integer.MIN_VALUE
345 static void getChars(int i, int index, char[] buf) {
355 // Generate two digits per iteration
358 // really: r = i - (q * 100);
359 r = i - ((q << 6) + (q << 5) + (q << 2));
361 buf [--charPos] = DigitOnes[r];
362 buf [--charPos] = DigitTens[r];
365 // Fall thru to fast mode for smaller numbers
366 // assert(i <= 65536, i);
368 q = (i * 52429) >>> (16+3);
369 r = i - ((q << 3) + (q << 1)); // r = i-(q*10) ...
370 buf [--charPos] = digits [r];
375 buf [--charPos] = sign;
379 final static int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
380 99999999, 999999999, Integer.MAX_VALUE };
382 // Requires positive x
383 static int stringSize(int x) {
385 if (x <= sizeTable[i])
390 * Parses the string argument as a signed integer in the radix
391 * specified by the second argument. The characters in the string
392 * must all be digits of the specified radix (as determined by
393 * whether {@link java.lang.Character#digit(char, int)} returns a
394 * nonnegative value), except that the first character may be an
395 * ASCII minus sign {@code '-'} (<code>'\u002D'</code>) to
396 * indicate a negative value or an ASCII plus sign {@code '+'}
397 * (<code>'\u002B'</code>) to indicate a positive value. The
398 * resulting integer value is returned.
400 * <p>An exception of type {@code NumberFormatException} is
401 * thrown if any of the following situations occurs:
403 * <li>The first argument is {@code null} or is a string of
406 * <li>The radix is either smaller than
407 * {@link java.lang.Character#MIN_RADIX} or
408 * larger than {@link java.lang.Character#MAX_RADIX}.
410 * <li>Any character of the string is not a digit of the specified
411 * radix, except that the first character may be a minus sign
412 * {@code '-'} (<code>'\u002D'</code>) or plus sign
413 * {@code '+'} (<code>'\u002B'</code>) provided that the
414 * string is longer than length 1.
416 * <li>The value represented by the string is not a value of type
422 * parseInt("0", 10) returns 0
423 * parseInt("473", 10) returns 473
424 * parseInt("+42", 10) returns 42
425 * parseInt("-0", 10) returns 0
426 * parseInt("-FF", 16) returns -255
427 * parseInt("1100110", 2) returns 102
428 * parseInt("2147483647", 10) returns 2147483647
429 * parseInt("-2147483648", 10) returns -2147483648
430 * parseInt("2147483648", 10) throws a NumberFormatException
431 * parseInt("99", 8) throws a NumberFormatException
432 * parseInt("Kona", 10) throws a NumberFormatException
433 * parseInt("Kona", 27) returns 411787
434 * </pre></blockquote>
436 * @param s the {@code String} containing the integer
437 * representation to be parsed
438 * @param radix the radix to be used while parsing {@code s}.
439 * @return the integer represented by the string argument in the
441 * @exception NumberFormatException if the {@code String}
442 * does not contain a parsable {@code int}.
444 @JavaScriptBody(args={"s", "radix"}, body="return parseInt(s,radix);")
445 public static int parseInt(String s, int radix)
446 throws NumberFormatException
449 * WARNING: This method may be invoked early during VM initialization
450 * before IntegerCache is initialized. Care must be taken to not use
451 * the valueOf method.
455 throw new NumberFormatException("null");
458 if (radix < Character.MIN_RADIX) {
459 throw new NumberFormatException("radix " + radix +
460 " less than Character.MIN_RADIX");
463 if (radix > Character.MAX_RADIX) {
464 throw new NumberFormatException("radix " + radix +
465 " greater than Character.MAX_RADIX");
469 boolean negative = false;
470 int i = 0, len = s.length();
471 int limit = -Integer.MAX_VALUE;
476 char firstChar = s.charAt(0);
477 if (firstChar < '0') { // Possible leading "+" or "-"
478 if (firstChar == '-') {
480 limit = Integer.MIN_VALUE;
481 } else if (firstChar != '+')
482 throw NumberFormatException.forInputString(s);
484 if (len == 1) // Cannot have lone "+" or "-"
485 throw NumberFormatException.forInputString(s);
488 multmin = limit / radix;
490 // Accumulating negatively avoids surprises near MAX_VALUE
491 digit = Character.digit(s.charAt(i++),radix);
493 throw NumberFormatException.forInputString(s);
495 if (result < multmin) {
496 throw NumberFormatException.forInputString(s);
499 if (result < limit + digit) {
500 throw NumberFormatException.forInputString(s);
505 throw NumberFormatException.forInputString(s);
507 return negative ? result : -result;
511 * Parses the string argument as a signed decimal integer. The
512 * characters in the string must all be decimal digits, except
513 * that the first character may be an ASCII minus sign {@code '-'}
514 * (<code>'\u002D'</code>) to indicate a negative value or an
515 * ASCII plus sign {@code '+'} (<code>'\u002B'</code>) to
516 * indicate a positive value. The resulting integer value is
517 * returned, exactly as if the argument and the radix 10 were
518 * given as arguments to the {@link #parseInt(java.lang.String,
521 * @param s a {@code String} containing the {@code int}
522 * representation to be parsed
523 * @return the integer value represented by the argument in decimal.
524 * @exception NumberFormatException if the string does not contain a
527 public static int parseInt(String s) throws NumberFormatException {
528 return parseInt(s,10);
532 * Returns an {@code Integer} object holding the value
533 * extracted from the specified {@code String} when parsed
534 * with the radix given by the second argument. The first argument
535 * is interpreted as representing a signed integer in the radix
536 * specified by the second argument, exactly as if the arguments
537 * were given to the {@link #parseInt(java.lang.String, int)}
538 * method. The result is an {@code Integer} object that
539 * represents the integer value specified by the string.
541 * <p>In other words, this method returns an {@code Integer}
542 * object equal to the value of:
545 * {@code new Integer(Integer.parseInt(s, radix))}
548 * @param s the string to be parsed.
549 * @param radix the radix to be used in interpreting {@code s}
550 * @return an {@code Integer} object holding the value
551 * represented by the string argument in the specified
553 * @exception NumberFormatException if the {@code String}
554 * does not contain a parsable {@code int}.
556 public static Integer valueOf(String s, int radix) throws NumberFormatException {
557 return Integer.valueOf(parseInt(s,radix));
561 * Returns an {@code Integer} object holding the
562 * value of the specified {@code String}. The argument is
563 * interpreted as representing a signed decimal integer, exactly
564 * as if the argument were given to the {@link
565 * #parseInt(java.lang.String)} method. The result is an
566 * {@code Integer} object that represents the integer value
567 * specified by the string.
569 * <p>In other words, this method returns an {@code Integer}
570 * object equal to the value of:
573 * {@code new Integer(Integer.parseInt(s))}
576 * @param s the string to be parsed.
577 * @return an {@code Integer} object holding the value
578 * represented by the string argument.
579 * @exception NumberFormatException if the string cannot be parsed
582 public static Integer valueOf(String s) throws NumberFormatException {
583 return Integer.valueOf(parseInt(s, 10));
587 * Cache to support the object identity semantics of autoboxing for values between
588 * -128 and 127 (inclusive) as required by JLS.
590 * The cache is initialized on first usage. The size of the cache
591 * may be controlled by the -XX:AutoBoxCacheMax=<size> option.
592 * During VM initialization, java.lang.Integer.IntegerCache.high property
593 * may be set and saved in the private system properties in the
597 private static class IntegerCache {
598 static final int low = -128;
599 static final int high;
600 static final Integer cache[];
603 // high value may be configured by property
605 String integerCacheHighPropValue =
606 AbstractStringBuilder.getProperty("java.lang.Integer.IntegerCache.high");
607 if (integerCacheHighPropValue != null) {
608 int i = parseInt(integerCacheHighPropValue);
609 i = Math.max(i, 127);
610 // Maximum array size is Integer.MAX_VALUE
611 h = Math.min(i, Integer.MAX_VALUE - (-low));
615 cache = new Integer[(high - low) + 1];
617 for(int k = 0; k < cache.length; k++)
618 cache[k] = new Integer(j++);
621 private IntegerCache() {}
625 * Returns an {@code Integer} instance representing the specified
626 * {@code int} value. If a new {@code Integer} instance is not
627 * required, this method should generally be used in preference to
628 * the constructor {@link #Integer(int)}, as this method is likely
629 * to yield significantly better space and time performance by
630 * caching frequently requested values.
632 * This method will always cache values in the range -128 to 127,
633 * inclusive, and may cache other values outside of this range.
635 * @param i an {@code int} value.
636 * @return an {@code Integer} instance representing {@code i}.
639 public static Integer valueOf(int i) {
640 //assert IntegerCache.high >= 127;
641 if (i >= IntegerCache.low && i <= IntegerCache.high)
642 return IntegerCache.cache[i + (-IntegerCache.low)];
643 return new Integer(i);
647 * The value of the {@code Integer}.
651 private final int value;
654 * Constructs a newly allocated {@code Integer} object that
655 * represents the specified {@code int} value.
657 * @param value the value to be represented by the
658 * {@code Integer} object.
660 public Integer(int value) {
665 * Constructs a newly allocated {@code Integer} object that
666 * represents the {@code int} value indicated by the
667 * {@code String} parameter. The string is converted to an
668 * {@code int} value in exactly the manner used by the
669 * {@code parseInt} method for radix 10.
671 * @param s the {@code String} to be converted to an
673 * @exception NumberFormatException if the {@code String} does not
674 * contain a parsable integer.
675 * @see java.lang.Integer#parseInt(java.lang.String, int)
677 public Integer(String s) throws NumberFormatException {
678 this.value = parseInt(s, 10);
682 * Returns the value of this {@code Integer} as a
685 public byte byteValue() {
690 * Returns the value of this {@code Integer} as a
693 public short shortValue() {
698 * Returns the value of this {@code Integer} as an
701 public int intValue() {
706 * Returns the value of this {@code Integer} as a
709 public long longValue() {
714 * Returns the value of this {@code Integer} as a
717 public float floatValue() {
722 * Returns the value of this {@code Integer} as a
725 public double doubleValue() {
726 return (double)value;
730 * Returns a {@code String} object representing this
731 * {@code Integer}'s value. The value is converted to signed
732 * decimal representation and returned as a string, exactly as if
733 * the integer value were given as an argument to the {@link
734 * java.lang.Integer#toString(int)} method.
736 * @return a string representation of the value of this object in
739 public String toString() {
740 return toString(value);
744 * Returns a hash code for this {@code Integer}.
746 * @return a hash code value for this object, equal to the
747 * primitive {@code int} value represented by this
748 * {@code Integer} object.
750 public int hashCode() {
755 * Compares this object to the specified object. The result is
756 * {@code true} if and only if the argument is not
757 * {@code null} and is an {@code Integer} object that
758 * contains the same {@code int} value as this object.
760 * @param obj the object to compare with.
761 * @return {@code true} if the objects are the same;
762 * {@code false} otherwise.
764 public boolean equals(Object obj) {
765 if (obj instanceof Integer) {
766 return value == ((Integer)obj).intValue();
772 * Determines the integer value of the system property with the
775 * <p>The first argument is treated as the name of a system property.
776 * System properties are accessible through the
777 * {@link java.lang.System#getProperty(java.lang.String)} method. The
778 * string value of this property is then interpreted as an integer
779 * value and an {@code Integer} object representing this value is
780 * returned. Details of possible numeric formats can be found with
781 * the definition of {@code getProperty}.
783 * <p>If there is no property with the specified name, if the specified name
784 * is empty or {@code null}, or if the property does not have
785 * the correct numeric format, then {@code null} is returned.
787 * <p>In other words, this method returns an {@code Integer}
788 * object equal to the value of:
791 * {@code getInteger(nm, null)}
794 * @param nm property name.
795 * @return the {@code Integer} value of the property.
796 * @see java.lang.System#getProperty(java.lang.String)
797 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
799 public static Integer getInteger(String nm) {
800 return getInteger(nm, null);
804 * Determines the integer value of the system property with the
807 * <p>The first argument is treated as the name of a system property.
808 * System properties are accessible through the {@link
809 * java.lang.System#getProperty(java.lang.String)} method. The
810 * string value of this property is then interpreted as an integer
811 * value and an {@code Integer} object representing this value is
812 * returned. Details of possible numeric formats can be found with
813 * the definition of {@code getProperty}.
815 * <p>The second argument is the default value. An {@code Integer} object
816 * that represents the value of the second argument is returned if there
817 * is no property of the specified name, if the property does not have
818 * the correct numeric format, or if the specified name is empty or
821 * <p>In other words, this method returns an {@code Integer} object
822 * equal to the value of:
825 * {@code getInteger(nm, new Integer(val))}
828 * but in practice it may be implemented in a manner such as:
831 * Integer result = getInteger(nm, null);
832 * return (result == null) ? new Integer(val) : result;
833 * </pre></blockquote>
835 * to avoid the unnecessary allocation of an {@code Integer}
836 * object when the default value is not needed.
838 * @param nm property name.
839 * @param val default value.
840 * @return the {@code Integer} value of the property.
841 * @see java.lang.System#getProperty(java.lang.String)
842 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
844 public static Integer getInteger(String nm, int val) {
845 Integer result = getInteger(nm, null);
846 return (result == null) ? Integer.valueOf(val) : result;
850 * Returns the integer value of the system property with the
851 * specified name. The first argument is treated as the name of a
852 * system property. System properties are accessible through the
853 * {@link java.lang.System#getProperty(java.lang.String)} method.
854 * The string value of this property is then interpreted as an
855 * integer value, as per the {@code Integer.decode} method,
856 * and an {@code Integer} object representing this value is
859 * <ul><li>If the property value begins with the two ASCII characters
860 * {@code 0x} or the ASCII character {@code #}, not
861 * followed by a minus sign, then the rest of it is parsed as a
862 * hexadecimal integer exactly as by the method
863 * {@link #valueOf(java.lang.String, int)} with radix 16.
864 * <li>If the property value begins with the ASCII character
865 * {@code 0} followed by another character, it is parsed as an
866 * octal integer exactly as by the method
867 * {@link #valueOf(java.lang.String, int)} with radix 8.
868 * <li>Otherwise, the property value is parsed as a decimal integer
869 * exactly as by the method {@link #valueOf(java.lang.String, int)}
873 * <p>The second argument is the default value. The default value is
874 * returned if there is no property of the specified name, if the
875 * property does not have the correct numeric format, or if the
876 * specified name is empty or {@code null}.
878 * @param nm property name.
879 * @param val default value.
880 * @return the {@code Integer} value of the property.
881 * @see java.lang.System#getProperty(java.lang.String)
882 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
883 * @see java.lang.Integer#decode
885 public static Integer getInteger(String nm, Integer val) {
888 v = AbstractStringBuilder.getProperty(nm);
889 } catch (IllegalArgumentException e) {
890 } catch (NullPointerException e) {
894 return Integer.decode(v);
895 } catch (NumberFormatException e) {
902 * Decodes a {@code String} into an {@code Integer}.
903 * Accepts decimal, hexadecimal, and octal numbers given
904 * by the following grammar:
908 * <dt><i>DecodableString:</i>
909 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
910 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
911 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
912 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
913 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
921 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
922 * are as defined in section 3.10.1 of
923 * <cite>The Java™ Language Specification</cite>,
924 * except that underscores are not accepted between digits.
926 * <p>The sequence of characters following an optional
927 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
928 * "{@code #}", or leading zero) is parsed as by the {@code
929 * Integer.parseInt} method with the indicated radix (10, 16, or
930 * 8). This sequence of characters must represent a positive
931 * value or a {@link NumberFormatException} will be thrown. The
932 * result is negated if first character of the specified {@code
933 * String} is the minus sign. No whitespace characters are
934 * permitted in the {@code String}.
936 * @param nm the {@code String} to decode.
937 * @return an {@code Integer} object holding the {@code int}
938 * value represented by {@code nm}
939 * @exception NumberFormatException if the {@code String} does not
940 * contain a parsable integer.
941 * @see java.lang.Integer#parseInt(java.lang.String, int)
943 public static Integer decode(String nm) throws NumberFormatException {
946 boolean negative = false;
949 if (nm.length() == 0)
950 throw new NumberFormatException("Zero length string");
951 char firstChar = nm.charAt(0);
952 // Handle sign, if present
953 if (firstChar == '-') {
956 } else if (firstChar == '+')
959 // Handle radix specifier, if present
960 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
964 else if (nm.startsWith("#", index)) {
968 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
973 if (nm.startsWith("-", index) || nm.startsWith("+", index))
974 throw new NumberFormatException("Sign character in wrong position");
977 result = Integer.valueOf(nm.substring(index), radix);
978 result = negative ? Integer.valueOf(-result.intValue()) : result;
979 } catch (NumberFormatException e) {
980 // If number is Integer.MIN_VALUE, we'll end up here. The next line
981 // handles this case, and causes any genuine format error to be
983 String constant = negative ? ("-" + nm.substring(index))
984 : nm.substring(index);
985 result = Integer.valueOf(constant, radix);
991 * Compares two {@code Integer} objects numerically.
993 * @param anotherInteger the {@code Integer} to be compared.
994 * @return the value {@code 0} if this {@code Integer} is
995 * equal to the argument {@code Integer}; a value less than
996 * {@code 0} if this {@code Integer} is numerically less
997 * than the argument {@code Integer}; and a value greater
998 * than {@code 0} if this {@code Integer} is numerically
999 * greater than the argument {@code Integer} (signed
1003 public int compareTo(Integer anotherInteger) {
1004 return compare(this.value, anotherInteger.value);
1008 * Compares two {@code int} values numerically.
1009 * The value returned is identical to what would be returned by:
1011 * Integer.valueOf(x).compareTo(Integer.valueOf(y))
1014 * @param x the first {@code int} to compare
1015 * @param y the second {@code int} to compare
1016 * @return the value {@code 0} if {@code x == y};
1017 * a value less than {@code 0} if {@code x < y}; and
1018 * a value greater than {@code 0} if {@code x > y}
1021 public static int compare(int x, int y) {
1022 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1029 * The number of bits used to represent an {@code int} value in two's
1030 * complement binary form.
1034 public static final int SIZE = 32;
1037 * Returns an {@code int} value with at most a single one-bit, in the
1038 * position of the highest-order ("leftmost") one-bit in the specified
1039 * {@code int} value. Returns zero if the specified value has no
1040 * one-bits in its two's complement binary representation, that is, if it
1043 * @return an {@code int} value with a single one-bit, in the position
1044 * of the highest-order one-bit in the specified value, or zero if
1045 * the specified value is itself equal to zero.
1048 public static int highestOneBit(int i) {
1055 return i - (i >>> 1);
1059 * Returns an {@code int} value with at most a single one-bit, in the
1060 * position of the lowest-order ("rightmost") one-bit in the specified
1061 * {@code int} value. Returns zero if the specified value has no
1062 * one-bits in its two's complement binary representation, that is, if it
1065 * @return an {@code int} value with a single one-bit, in the position
1066 * of the lowest-order one-bit in the specified value, or zero if
1067 * the specified value is itself equal to zero.
1070 public static int lowestOneBit(int i) {
1076 * Returns the number of zero bits preceding the highest-order
1077 * ("leftmost") one-bit in the two's complement binary representation
1078 * of the specified {@code int} value. Returns 32 if the
1079 * specified value has no one-bits in its two's complement representation,
1080 * in other words if it is equal to zero.
1082 * <p>Note that this method is closely related to the logarithm base 2.
1083 * For all positive {@code int} values x:
1085 * <li>floor(log<sub>2</sub>(x)) = {@code 31 - numberOfLeadingZeros(x)}
1086 * <li>ceil(log<sub>2</sub>(x)) = {@code 32 - numberOfLeadingZeros(x - 1)}
1089 * @return the number of zero bits preceding the highest-order
1090 * ("leftmost") one-bit in the two's complement binary representation
1091 * of the specified {@code int} value, or 32 if the value
1095 public static int numberOfLeadingZeros(int i) {
1100 if (i >>> 16 == 0) { n += 16; i <<= 16; }
1101 if (i >>> 24 == 0) { n += 8; i <<= 8; }
1102 if (i >>> 28 == 0) { n += 4; i <<= 4; }
1103 if (i >>> 30 == 0) { n += 2; i <<= 2; }
1109 * Returns the number of zero bits following the lowest-order ("rightmost")
1110 * one-bit in the two's complement binary representation of the specified
1111 * {@code int} value. Returns 32 if the specified value has no
1112 * one-bits in its two's complement representation, in other words if it is
1115 * @return the number of zero bits following the lowest-order ("rightmost")
1116 * one-bit in the two's complement binary representation of the
1117 * specified {@code int} value, or 32 if the value is equal
1121 public static int numberOfTrailingZeros(int i) {
1124 if (i == 0) return 32;
1126 y = i <<16; if (y != 0) { n = n -16; i = y; }
1127 y = i << 8; if (y != 0) { n = n - 8; i = y; }
1128 y = i << 4; if (y != 0) { n = n - 4; i = y; }
1129 y = i << 2; if (y != 0) { n = n - 2; i = y; }
1130 return n - ((i << 1) >>> 31);
1134 * Returns the number of one-bits in the two's complement binary
1135 * representation of the specified {@code int} value. This function is
1136 * sometimes referred to as the <i>population count</i>.
1138 * @return the number of one-bits in the two's complement binary
1139 * representation of the specified {@code int} value.
1142 public static int bitCount(int i) {
1144 i = i - ((i >>> 1) & 0x55555555);
1145 i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
1146 i = (i + (i >>> 4)) & 0x0f0f0f0f;
1153 * Returns the value obtained by rotating the two's complement binary
1154 * representation of the specified {@code int} value left by the
1155 * specified number of bits. (Bits shifted out of the left hand, or
1156 * high-order, side reenter on the right, or low-order.)
1158 * <p>Note that left rotation with a negative distance is equivalent to
1159 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1160 * distance)}. Note also that rotation by any multiple of 32 is a
1161 * no-op, so all but the last five bits of the rotation distance can be
1162 * ignored, even if the distance is negative: {@code rotateLeft(val,
1163 * distance) == rotateLeft(val, distance & 0x1F)}.
1165 * @return the value obtained by rotating the two's complement binary
1166 * representation of the specified {@code int} value left by the
1167 * specified number of bits.
1170 public static int rotateLeft(int i, int distance) {
1171 return (i << distance) | (i >>> -distance);
1175 * Returns the value obtained by rotating the two's complement binary
1176 * representation of the specified {@code int} value right by the
1177 * specified number of bits. (Bits shifted out of the right hand, or
1178 * low-order, side reenter on the left, or high-order.)
1180 * <p>Note that right rotation with a negative distance is equivalent to
1181 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1182 * distance)}. Note also that rotation by any multiple of 32 is a
1183 * no-op, so all but the last five bits of the rotation distance can be
1184 * ignored, even if the distance is negative: {@code rotateRight(val,
1185 * distance) == rotateRight(val, distance & 0x1F)}.
1187 * @return the value obtained by rotating the two's complement binary
1188 * representation of the specified {@code int} value right by the
1189 * specified number of bits.
1192 public static int rotateRight(int i, int distance) {
1193 return (i >>> distance) | (i << -distance);
1197 * Returns the value obtained by reversing the order of the bits in the
1198 * two's complement binary representation of the specified {@code int}
1201 * @return the value obtained by reversing order of the bits in the
1202 * specified {@code int} value.
1205 public static int reverse(int i) {
1207 i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
1208 i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333;
1209 i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
1210 i = (i << 24) | ((i & 0xff00) << 8) |
1211 ((i >>> 8) & 0xff00) | (i >>> 24);
1216 * Returns the signum function of the specified {@code int} value. (The
1217 * return value is -1 if the specified value is negative; 0 if the
1218 * specified value is zero; and 1 if the specified value is positive.)
1220 * @return the signum function of the specified {@code int} value.
1223 public static int signum(int i) {
1225 return (i >> 31) | (-i >>> 31);
1229 * Returns the value obtained by reversing the order of the bytes in the
1230 * two's complement representation of the specified {@code int} value.
1232 * @return the value obtained by reversing the bytes in the specified
1233 * {@code int} value.
1236 public static int reverseBytes(int i) {
1237 return ((i >>> 24) ) |
1238 ((i >> 8) & 0xFF00) |
1239 ((i << 8) & 0xFF0000) |
1243 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1244 private static final long serialVersionUID = 1360826667806852920L;