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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
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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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 @JavaScriptBody(args = "i", body = "return i.toString();")
328 public static String toString(int i) {
329 if (i == Integer.MIN_VALUE)
330 return "-2147483648";
331 int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
332 char[] buf = new char[size];
333 getChars(i, size, buf);
334 return new String(buf, 0, size);
338 * Places characters representing the integer i into the
339 * character array buf. The characters are placed into
340 * the buffer backwards starting with the least significant
341 * digit at the specified index (exclusive), and working
342 * backwards from there.
344 * Will fail if i == Integer.MIN_VALUE
346 static void getChars(int i, int index, char[] buf) {
356 // Generate two digits per iteration
359 // really: r = i - (q * 100);
360 r = i - ((q << 6) + (q << 5) + (q << 2));
362 buf [--charPos] = DigitOnes[r];
363 buf [--charPos] = DigitTens[r];
366 // Fall thru to fast mode for smaller numbers
367 // assert(i <= 65536, i);
369 q = (i * 52429) >>> (16+3);
370 r = i - ((q << 3) + (q << 1)); // r = i-(q*10) ...
371 buf [--charPos] = digits [r];
376 buf [--charPos] = sign;
380 final static int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
381 99999999, 999999999, Integer.MAX_VALUE };
383 // Requires positive x
384 static int stringSize(int x) {
386 if (x <= sizeTable[i])
391 * Parses the string argument as a signed integer in the radix
392 * specified by the second argument. The characters in the string
393 * must all be digits of the specified radix (as determined by
394 * whether {@link java.lang.Character#digit(char, int)} returns a
395 * nonnegative value), except that the first character may be an
396 * ASCII minus sign {@code '-'} (<code>'\u002D'</code>) to
397 * indicate a negative value or an ASCII plus sign {@code '+'}
398 * (<code>'\u002B'</code>) to indicate a positive value. The
399 * resulting integer value is returned.
401 * <p>An exception of type {@code NumberFormatException} is
402 * thrown if any of the following situations occurs:
404 * <li>The first argument is {@code null} or is a string of
407 * <li>The radix is either smaller than
408 * {@link java.lang.Character#MIN_RADIX} or
409 * larger than {@link java.lang.Character#MAX_RADIX}.
411 * <li>Any character of the string is not a digit of the specified
412 * radix, except that the first character may be a minus sign
413 * {@code '-'} (<code>'\u002D'</code>) or plus sign
414 * {@code '+'} (<code>'\u002B'</code>) provided that the
415 * string is longer than length 1.
417 * <li>The value represented by the string is not a value of type
423 * parseInt("0", 10) returns 0
424 * parseInt("473", 10) returns 473
425 * parseInt("+42", 10) returns 42
426 * parseInt("-0", 10) returns 0
427 * parseInt("-FF", 16) returns -255
428 * parseInt("1100110", 2) returns 102
429 * parseInt("2147483647", 10) returns 2147483647
430 * parseInt("-2147483648", 10) returns -2147483648
431 * parseInt("2147483648", 10) throws a NumberFormatException
432 * parseInt("99", 8) throws a NumberFormatException
433 * parseInt("Kona", 10) throws a NumberFormatException
434 * parseInt("Kona", 27) returns 411787
435 * </pre></blockquote>
437 * @param s the {@code String} containing the integer
438 * representation to be parsed
439 * @param radix the radix to be used while parsing {@code s}.
440 * @return the integer represented by the string argument in the
442 * @exception NumberFormatException if the {@code String}
443 * does not contain a parsable {@code int}.
445 @JavaScriptBody(args={"s", "radix"}, body="return parseInt(s,radix);")
446 public static int parseInt(String s, int radix)
447 throws NumberFormatException
450 * WARNING: This method may be invoked early during VM initialization
451 * before IntegerCache is initialized. Care must be taken to not use
452 * the valueOf method.
456 throw new NumberFormatException("null");
459 if (radix < Character.MIN_RADIX) {
460 throw new NumberFormatException("radix " + radix +
461 " less than Character.MIN_RADIX");
464 if (radix > Character.MAX_RADIX) {
465 throw new NumberFormatException("radix " + radix +
466 " greater than Character.MAX_RADIX");
470 boolean negative = false;
471 int i = 0, len = s.length();
472 int limit = -Integer.MAX_VALUE;
477 char firstChar = s.charAt(0);
478 if (firstChar < '0') { // Possible leading "+" or "-"
479 if (firstChar == '-') {
481 limit = Integer.MIN_VALUE;
482 } else if (firstChar != '+')
483 throw NumberFormatException.forInputString(s);
485 if (len == 1) // Cannot have lone "+" or "-"
486 throw NumberFormatException.forInputString(s);
489 multmin = limit / radix;
491 // Accumulating negatively avoids surprises near MAX_VALUE
492 digit = Character.digit(s.charAt(i++),radix);
494 throw NumberFormatException.forInputString(s);
496 if (result < multmin) {
497 throw NumberFormatException.forInputString(s);
500 if (result < limit + digit) {
501 throw NumberFormatException.forInputString(s);
506 throw NumberFormatException.forInputString(s);
508 return negative ? result : -result;
512 * Parses the string argument as a signed decimal integer. The
513 * characters in the string must all be decimal digits, except
514 * that the first character may be an ASCII minus sign {@code '-'}
515 * (<code>'\u002D'</code>) to indicate a negative value or an
516 * ASCII plus sign {@code '+'} (<code>'\u002B'</code>) to
517 * indicate a positive value. The resulting integer value is
518 * returned, exactly as if the argument and the radix 10 were
519 * given as arguments to the {@link #parseInt(java.lang.String,
522 * @param s a {@code String} containing the {@code int}
523 * representation to be parsed
524 * @return the integer value represented by the argument in decimal.
525 * @exception NumberFormatException if the string does not contain a
528 public static int parseInt(String s) throws NumberFormatException {
529 return parseInt(s,10);
533 * Returns an {@code Integer} object holding the value
534 * extracted from the specified {@code String} when parsed
535 * with the radix given by the second argument. The first argument
536 * is interpreted as representing a signed integer in the radix
537 * specified by the second argument, exactly as if the arguments
538 * were given to the {@link #parseInt(java.lang.String, int)}
539 * method. The result is an {@code Integer} object that
540 * represents the integer value specified by the string.
542 * <p>In other words, this method returns an {@code Integer}
543 * object equal to the value of:
546 * {@code new Integer(Integer.parseInt(s, radix))}
549 * @param s the string to be parsed.
550 * @param radix the radix to be used in interpreting {@code s}
551 * @return an {@code Integer} object holding the value
552 * represented by the string argument in the specified
554 * @exception NumberFormatException if the {@code String}
555 * does not contain a parsable {@code int}.
557 public static Integer valueOf(String s, int radix) throws NumberFormatException {
558 return Integer.valueOf(parseInt(s,radix));
562 * Returns an {@code Integer} object holding the
563 * value of the specified {@code String}. The argument is
564 * interpreted as representing a signed decimal integer, exactly
565 * as if the argument were given to the {@link
566 * #parseInt(java.lang.String)} method. The result is an
567 * {@code Integer} object that represents the integer value
568 * specified by the string.
570 * <p>In other words, this method returns an {@code Integer}
571 * object equal to the value of:
574 * {@code new Integer(Integer.parseInt(s))}
577 * @param s the string to be parsed.
578 * @return an {@code Integer} object holding the value
579 * represented by the string argument.
580 * @exception NumberFormatException if the string cannot be parsed
583 public static Integer valueOf(String s) throws NumberFormatException {
584 return Integer.valueOf(parseInt(s, 10));
588 * Cache to support the object identity semantics of autoboxing for values between
589 * -128 and 127 (inclusive) as required by JLS.
591 * The cache is initialized on first usage. The size of the cache
592 * may be controlled by the -XX:AutoBoxCacheMax=<size> option.
593 * During VM initialization, java.lang.Integer.IntegerCache.high property
594 * may be set and saved in the private system properties in the
598 private static class IntegerCache {
599 static final int low = -128;
600 static final int high;
601 static final Integer cache[];
604 // high value may be configured by property
606 String integerCacheHighPropValue =
607 AbstractStringBuilder.getProperty("java.lang.Integer.IntegerCache.high");
608 if (integerCacheHighPropValue != null) {
609 int i = parseInt(integerCacheHighPropValue);
610 i = Math.max(i, 127);
611 // Maximum array size is Integer.MAX_VALUE
612 h = Math.min(i, Integer.MAX_VALUE - (-low));
616 cache = new Integer[(high - low) + 1];
618 for(int k = 0; k < cache.length; k++)
619 cache[k] = new Integer(j++);
622 private IntegerCache() {}
626 * Returns an {@code Integer} instance representing the specified
627 * {@code int} value. If a new {@code Integer} instance is not
628 * required, this method should generally be used in preference to
629 * the constructor {@link #Integer(int)}, as this method is likely
630 * to yield significantly better space and time performance by
631 * caching frequently requested values.
633 * This method will always cache values in the range -128 to 127,
634 * inclusive, and may cache other values outside of this range.
636 * @param i an {@code int} value.
637 * @return an {@code Integer} instance representing {@code i}.
640 public static Integer valueOf(int i) {
641 //assert IntegerCache.high >= 127;
642 if (i >= IntegerCache.low && i <= IntegerCache.high)
643 return IntegerCache.cache[i + (-IntegerCache.low)];
644 return new Integer(i);
648 * The value of the {@code Integer}.
652 private final int value;
655 * Constructs a newly allocated {@code Integer} object that
656 * represents the specified {@code int} value.
658 * @param value the value to be represented by the
659 * {@code Integer} object.
661 public Integer(int value) {
666 * Constructs a newly allocated {@code Integer} object that
667 * represents the {@code int} value indicated by the
668 * {@code String} parameter. The string is converted to an
669 * {@code int} value in exactly the manner used by the
670 * {@code parseInt} method for radix 10.
672 * @param s the {@code String} to be converted to an
674 * @exception NumberFormatException if the {@code String} does not
675 * contain a parsable integer.
676 * @see java.lang.Integer#parseInt(java.lang.String, int)
678 public Integer(String s) throws NumberFormatException {
679 this.value = parseInt(s, 10);
683 * Returns the value of this {@code Integer} as a
686 public byte byteValue() {
691 * Returns the value of this {@code Integer} as a
694 public short shortValue() {
699 * Returns the value of this {@code Integer} as an
702 public int intValue() {
707 * Returns the value of this {@code Integer} as a
710 public long longValue() {
715 * Returns the value of this {@code Integer} as a
718 public float floatValue() {
723 * Returns the value of this {@code Integer} as a
726 public double doubleValue() {
727 return (double)value;
731 * Returns a {@code String} object representing this
732 * {@code Integer}'s value. The value is converted to signed
733 * decimal representation and returned as a string, exactly as if
734 * the integer value were given as an argument to the {@link
735 * java.lang.Integer#toString(int)} method.
737 * @return a string representation of the value of this object in
740 public String toString() {
741 return toString(value);
745 * Returns a hash code for this {@code Integer}.
747 * @return a hash code value for this object, equal to the
748 * primitive {@code int} value represented by this
749 * {@code Integer} object.
751 public int hashCode() {
756 * Compares this object to the specified object. The result is
757 * {@code true} if and only if the argument is not
758 * {@code null} and is an {@code Integer} object that
759 * contains the same {@code int} value as this object.
761 * @param obj the object to compare with.
762 * @return {@code true} if the objects are the same;
763 * {@code false} otherwise.
765 public boolean equals(Object obj) {
766 if (obj instanceof Integer) {
767 return value == ((Integer)obj).intValue();
773 * Determines the integer value of the system property with the
776 * <p>The first argument is treated as the name of a system property.
777 * System properties are accessible through the
778 * {@link java.lang.System#getProperty(java.lang.String)} method. The
779 * string value of this property is then interpreted as an integer
780 * value and an {@code Integer} object representing this value is
781 * returned. Details of possible numeric formats can be found with
782 * the definition of {@code getProperty}.
784 * <p>If there is no property with the specified name, if the specified name
785 * is empty or {@code null}, or if the property does not have
786 * the correct numeric format, then {@code null} is returned.
788 * <p>In other words, this method returns an {@code Integer}
789 * object equal to the value of:
792 * {@code getInteger(nm, null)}
795 * @param nm property name.
796 * @return the {@code Integer} value of the property.
797 * @see java.lang.System#getProperty(java.lang.String)
798 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
800 public static Integer getInteger(String nm) {
801 return getInteger(nm, null);
805 * Determines the integer value of the system property with the
808 * <p>The first argument is treated as the name of a system property.
809 * System properties are accessible through the {@link
810 * java.lang.System#getProperty(java.lang.String)} method. The
811 * string value of this property is then interpreted as an integer
812 * value and an {@code Integer} object representing this value is
813 * returned. Details of possible numeric formats can be found with
814 * the definition of {@code getProperty}.
816 * <p>The second argument is the default value. An {@code Integer} object
817 * that represents the value of the second argument is returned if there
818 * is no property of the specified name, if the property does not have
819 * the correct numeric format, or if the specified name is empty or
822 * <p>In other words, this method returns an {@code Integer} object
823 * equal to the value of:
826 * {@code getInteger(nm, new Integer(val))}
829 * but in practice it may be implemented in a manner such as:
832 * Integer result = getInteger(nm, null);
833 * return (result == null) ? new Integer(val) : result;
834 * </pre></blockquote>
836 * to avoid the unnecessary allocation of an {@code Integer}
837 * object when the default value is not needed.
839 * @param nm property name.
840 * @param val default value.
841 * @return the {@code Integer} value of the property.
842 * @see java.lang.System#getProperty(java.lang.String)
843 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
845 public static Integer getInteger(String nm, int val) {
846 Integer result = getInteger(nm, null);
847 return (result == null) ? Integer.valueOf(val) : result;
851 * Returns the integer value of the system property with the
852 * specified name. The first argument is treated as the name of a
853 * system property. System properties are accessible through the
854 * {@link java.lang.System#getProperty(java.lang.String)} method.
855 * The string value of this property is then interpreted as an
856 * integer value, as per the {@code Integer.decode} method,
857 * and an {@code Integer} object representing this value is
860 * <ul><li>If the property value begins with the two ASCII characters
861 * {@code 0x} or the ASCII character {@code #}, not
862 * followed by a minus sign, then the rest of it is parsed as a
863 * hexadecimal integer exactly as by the method
864 * {@link #valueOf(java.lang.String, int)} with radix 16.
865 * <li>If the property value begins with the ASCII character
866 * {@code 0} followed by another character, it is parsed as an
867 * octal integer exactly as by the method
868 * {@link #valueOf(java.lang.String, int)} with radix 8.
869 * <li>Otherwise, the property value is parsed as a decimal integer
870 * exactly as by the method {@link #valueOf(java.lang.String, int)}
874 * <p>The second argument is the default value. The default value is
875 * returned if there is no property of the specified name, if the
876 * property does not have the correct numeric format, or if the
877 * specified name is empty or {@code null}.
879 * @param nm property name.
880 * @param val default value.
881 * @return the {@code Integer} value of the property.
882 * @see java.lang.System#getProperty(java.lang.String)
883 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
884 * @see java.lang.Integer#decode
886 public static Integer getInteger(String nm, Integer val) {
889 v = AbstractStringBuilder.getProperty(nm);
890 } catch (IllegalArgumentException e) {
891 } catch (NullPointerException e) {
895 return Integer.decode(v);
896 } catch (NumberFormatException e) {
903 * Decodes a {@code String} into an {@code Integer}.
904 * Accepts decimal, hexadecimal, and octal numbers given
905 * by the following grammar:
909 * <dt><i>DecodableString:</i>
910 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
911 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
912 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
913 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
914 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
922 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
923 * are as defined in section 3.10.1 of
924 * <cite>The Java™ Language Specification</cite>,
925 * except that underscores are not accepted between digits.
927 * <p>The sequence of characters following an optional
928 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
929 * "{@code #}", or leading zero) is parsed as by the {@code
930 * Integer.parseInt} method with the indicated radix (10, 16, or
931 * 8). This sequence of characters must represent a positive
932 * value or a {@link NumberFormatException} will be thrown. The
933 * result is negated if first character of the specified {@code
934 * String} is the minus sign. No whitespace characters are
935 * permitted in the {@code String}.
937 * @param nm the {@code String} to decode.
938 * @return an {@code Integer} object holding the {@code int}
939 * value represented by {@code nm}
940 * @exception NumberFormatException if the {@code String} does not
941 * contain a parsable integer.
942 * @see java.lang.Integer#parseInt(java.lang.String, int)
944 public static Integer decode(String nm) throws NumberFormatException {
947 boolean negative = false;
950 if (nm.length() == 0)
951 throw new NumberFormatException("Zero length string");
952 char firstChar = nm.charAt(0);
953 // Handle sign, if present
954 if (firstChar == '-') {
957 } else if (firstChar == '+')
960 // Handle radix specifier, if present
961 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
965 else if (nm.startsWith("#", index)) {
969 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
974 if (nm.startsWith("-", index) || nm.startsWith("+", index))
975 throw new NumberFormatException("Sign character in wrong position");
978 result = Integer.valueOf(nm.substring(index), radix);
979 result = negative ? Integer.valueOf(-result.intValue()) : result;
980 } catch (NumberFormatException e) {
981 // If number is Integer.MIN_VALUE, we'll end up here. The next line
982 // handles this case, and causes any genuine format error to be
984 String constant = negative ? ("-" + nm.substring(index))
985 : nm.substring(index);
986 result = Integer.valueOf(constant, radix);
992 * Compares two {@code Integer} objects numerically.
994 * @param anotherInteger the {@code Integer} to be compared.
995 * @return the value {@code 0} if this {@code Integer} is
996 * equal to the argument {@code Integer}; a value less than
997 * {@code 0} if this {@code Integer} is numerically less
998 * than the argument {@code Integer}; and a value greater
999 * than {@code 0} if this {@code Integer} is numerically
1000 * greater than the argument {@code Integer} (signed
1004 public int compareTo(Integer anotherInteger) {
1005 return compare(this.value, anotherInteger.value);
1009 * Compares two {@code int} values numerically.
1010 * The value returned is identical to what would be returned by:
1012 * Integer.valueOf(x).compareTo(Integer.valueOf(y))
1015 * @param x the first {@code int} to compare
1016 * @param y the second {@code int} to compare
1017 * @return the value {@code 0} if {@code x == y};
1018 * a value less than {@code 0} if {@code x < y}; and
1019 * a value greater than {@code 0} if {@code x > y}
1022 public static int compare(int x, int y) {
1023 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1030 * The number of bits used to represent an {@code int} value in two's
1031 * complement binary form.
1035 public static final int SIZE = 32;
1038 * Returns an {@code int} value with at most a single one-bit, in the
1039 * position of the highest-order ("leftmost") one-bit in the specified
1040 * {@code int} value. Returns zero if the specified value has no
1041 * one-bits in its two's complement binary representation, that is, if it
1044 * @return an {@code int} value with a single one-bit, in the position
1045 * of the highest-order one-bit in the specified value, or zero if
1046 * the specified value is itself equal to zero.
1049 public static int highestOneBit(int i) {
1056 return i - (i >>> 1);
1060 * Returns an {@code int} value with at most a single one-bit, in the
1061 * position of the lowest-order ("rightmost") one-bit in the specified
1062 * {@code int} value. Returns zero if the specified value has no
1063 * one-bits in its two's complement binary representation, that is, if it
1066 * @return an {@code int} value with a single one-bit, in the position
1067 * of the lowest-order one-bit in the specified value, or zero if
1068 * the specified value is itself equal to zero.
1071 public static int lowestOneBit(int i) {
1077 * Returns the number of zero bits preceding the highest-order
1078 * ("leftmost") one-bit in the two's complement binary representation
1079 * of the specified {@code int} value. Returns 32 if the
1080 * specified value has no one-bits in its two's complement representation,
1081 * in other words if it is equal to zero.
1083 * <p>Note that this method is closely related to the logarithm base 2.
1084 * For all positive {@code int} values x:
1086 * <li>floor(log<sub>2</sub>(x)) = {@code 31 - numberOfLeadingZeros(x)}
1087 * <li>ceil(log<sub>2</sub>(x)) = {@code 32 - numberOfLeadingZeros(x - 1)}
1090 * @return the number of zero bits preceding the highest-order
1091 * ("leftmost") one-bit in the two's complement binary representation
1092 * of the specified {@code int} value, or 32 if the value
1096 public static int numberOfLeadingZeros(int i) {
1101 if (i >>> 16 == 0) { n += 16; i <<= 16; }
1102 if (i >>> 24 == 0) { n += 8; i <<= 8; }
1103 if (i >>> 28 == 0) { n += 4; i <<= 4; }
1104 if (i >>> 30 == 0) { n += 2; i <<= 2; }
1110 * Returns the number of zero bits following the lowest-order ("rightmost")
1111 * one-bit in the two's complement binary representation of the specified
1112 * {@code int} value. Returns 32 if the specified value has no
1113 * one-bits in its two's complement representation, in other words if it is
1116 * @return the number of zero bits following the lowest-order ("rightmost")
1117 * one-bit in the two's complement binary representation of the
1118 * specified {@code int} value, or 32 if the value is equal
1122 public static int numberOfTrailingZeros(int i) {
1125 if (i == 0) return 32;
1127 y = i <<16; if (y != 0) { n = n -16; i = y; }
1128 y = i << 8; if (y != 0) { n = n - 8; i = y; }
1129 y = i << 4; if (y != 0) { n = n - 4; i = y; }
1130 y = i << 2; if (y != 0) { n = n - 2; i = y; }
1131 return n - ((i << 1) >>> 31);
1135 * Returns the number of one-bits in the two's complement binary
1136 * representation of the specified {@code int} value. This function is
1137 * sometimes referred to as the <i>population count</i>.
1139 * @return the number of one-bits in the two's complement binary
1140 * representation of the specified {@code int} value.
1143 public static int bitCount(int i) {
1145 i = i - ((i >>> 1) & 0x55555555);
1146 i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
1147 i = (i + (i >>> 4)) & 0x0f0f0f0f;
1154 * Returns the value obtained by rotating the two's complement binary
1155 * representation of the specified {@code int} value left by the
1156 * specified number of bits. (Bits shifted out of the left hand, or
1157 * high-order, side reenter on the right, or low-order.)
1159 * <p>Note that left rotation with a negative distance is equivalent to
1160 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1161 * distance)}. Note also that rotation by any multiple of 32 is a
1162 * no-op, so all but the last five bits of the rotation distance can be
1163 * ignored, even if the distance is negative: {@code rotateLeft(val,
1164 * distance) == rotateLeft(val, distance & 0x1F)}.
1166 * @return the value obtained by rotating the two's complement binary
1167 * representation of the specified {@code int} value left by the
1168 * specified number of bits.
1171 public static int rotateLeft(int i, int distance) {
1172 return (i << distance) | (i >>> -distance);
1176 * Returns the value obtained by rotating the two's complement binary
1177 * representation of the specified {@code int} value right by the
1178 * specified number of bits. (Bits shifted out of the right hand, or
1179 * low-order, side reenter on the left, or high-order.)
1181 * <p>Note that right rotation with a negative distance is equivalent to
1182 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1183 * distance)}. Note also that rotation by any multiple of 32 is a
1184 * no-op, so all but the last five bits of the rotation distance can be
1185 * ignored, even if the distance is negative: {@code rotateRight(val,
1186 * distance) == rotateRight(val, distance & 0x1F)}.
1188 * @return the value obtained by rotating the two's complement binary
1189 * representation of the specified {@code int} value right by the
1190 * specified number of bits.
1193 public static int rotateRight(int i, int distance) {
1194 return (i >>> distance) | (i << -distance);
1198 * Returns the value obtained by reversing the order of the bits in the
1199 * two's complement binary representation of the specified {@code int}
1202 * @return the value obtained by reversing order of the bits in the
1203 * specified {@code int} value.
1206 public static int reverse(int i) {
1208 i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
1209 i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333;
1210 i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
1211 i = (i << 24) | ((i & 0xff00) << 8) |
1212 ((i >>> 8) & 0xff00) | (i >>> 24);
1217 * Returns the signum function of the specified {@code int} value. (The
1218 * return value is -1 if the specified value is negative; 0 if the
1219 * specified value is zero; and 1 if the specified value is positive.)
1221 * @return the signum function of the specified {@code int} value.
1224 public static int signum(int i) {
1226 return (i >> 31) | (-i >>> 31);
1230 * Returns the value obtained by reversing the order of the bytes in the
1231 * two's complement representation of the specified {@code int} value.
1233 * @return the value obtained by reversing the bytes in the specified
1234 * {@code int} value.
1237 public static int reverseBytes(int i) {
1238 return ((i >>> 24) ) |
1239 ((i >> 8) & 0xFF00) |
1240 ((i << 8) & 0xFF0000) |
1244 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1245 private static final long serialVersionUID = 1360826667806852920L;