In addition, this class provides several methods for converting - * an {@code int} to a {@code String} and a {@code String} to an - * {@code int}, as well as other constants and methods useful when - * dealing with an {@code int}. - * - *
Implementation note: The implementations of the "bit twiddling"
- * methods (such as {@link #highestOneBit(int) highestOneBit} and
- * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
- * based on material from Henry S. Warren, Jr.'s Hacker's
- * Delight, (Addison Wesley, 2002).
- *
- * @author Lee Boynton
- * @author Arthur van Hoff
- * @author Josh Bloch
- * @author Joseph D. Darcy
- * @since JDK1.0
- */
-public final class Integer extends Number implements Comparable If the radix is smaller than {@code Character.MIN_RADIX}
- * or larger than {@code Character.MAX_RADIX}, then the radix
- * {@code 10} is used instead.
- *
- * If the first argument is negative, the first element of the
- * result is the ASCII minus character {@code '-'}
- * ( The remaining characters of the result represent the magnitude
- * of the first argument. If the magnitude is zero, it is
- * represented by a single zero character {@code '0'}
- * ( The unsigned integer value is the argument plus 232
- * if the argument is negative; otherwise, it is equal to the
- * argument. This value is converted to a string of ASCII digits
- * in hexadecimal (base 16) with no extra leading
- * {@code 0}s. If the unsigned magnitude is zero, it is
- * represented by a single zero character {@code '0'}
- * ( The unsigned integer value is the argument plus 232
- * if the argument is negative; otherwise, it is equal to the
- * argument. This value is converted to a string of ASCII digits
- * in octal (base 8) with no extra leading {@code 0}s.
- *
- * If the unsigned magnitude is zero, it is represented by a
- * single zero character {@code '0'}
- * ( The unsigned integer value is the argument plus 232
- * if the argument is negative; otherwise it is equal to the
- * argument. This value is converted to a string of ASCII digits
- * in binary (base 2) with no extra leading {@code 0}s.
- * If the unsigned magnitude is zero, it is represented by a
- * single zero character {@code '0'}
- * ( An exception of type {@code NumberFormatException} is
- * thrown if any of the following situations occurs:
- * Examples:
- * In other words, this method returns an {@code Integer}
- * object equal to the value of:
- *
- * In other words, this method returns an {@code Integer}
- * object equal to the value of:
- *
- * The first argument is treated as the name of a system property.
- * System properties are accessible through the
- * {@link java.lang.System#getProperty(java.lang.String)} method. The
- * string value of this property is then interpreted as an integer
- * value and an {@code Integer} object representing this value is
- * returned. Details of possible numeric formats can be found with
- * the definition of {@code getProperty}.
- *
- * If there is no property with the specified name, if the specified name
- * is empty or {@code null}, or if the property does not have
- * the correct numeric format, then {@code null} is returned.
- *
- * In other words, this method returns an {@code Integer}
- * object equal to the value of:
- *
- * The first argument is treated as the name of a system property.
- * System properties are accessible through the {@link
- * java.lang.System#getProperty(java.lang.String)} method. The
- * string value of this property is then interpreted as an integer
- * value and an {@code Integer} object representing this value is
- * returned. Details of possible numeric formats can be found with
- * the definition of {@code getProperty}.
- *
- * The second argument is the default value. An {@code Integer} object
- * that represents the value of the second argument is returned if there
- * is no property of the specified name, if the property does not have
- * the correct numeric format, or if the specified name is empty or
- * {@code null}.
- *
- * In other words, this method returns an {@code Integer} object
- * equal to the value of:
- *
- * The second argument is the default value. The default value is
- * returned if there is no property of the specified name, if the
- * property does not have the correct numeric format, or if the
- * specified name is empty or {@code null}.
- *
- * @param nm property name.
- * @param val default value.
- * @return the {@code Integer} value of the property.
- * @see java.lang.System#getProperty(java.lang.String)
- * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
- * @see java.lang.Integer#decode
- */
- public static Integer getInteger(String nm, Integer val) {
- String v = null;
- try {
- v = AbstractStringBuilder.getProperty(nm);
- } catch (IllegalArgumentException e) {
- } catch (NullPointerException e) {
- }
- if (v != null) {
- try {
- return Integer.decode(v);
- } catch (NumberFormatException e) {
- }
- }
- return val;
- }
-
- /**
- * Decodes a {@code String} into an {@code Integer}.
- * Accepts decimal, hexadecimal, and octal numbers given
- * by the following grammar:
- *
- *
- * The sequence of characters following an optional
- * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
- * "{@code #}", or leading zero) is parsed as by the {@code
- * Integer.parseInt} method with the indicated radix (10, 16, or
- * 8). This sequence of characters must represent a positive
- * value or a {@link NumberFormatException} will be thrown. The
- * result is negated if first character of the specified {@code
- * String} is the minus sign. No whitespace characters are
- * permitted in the {@code String}.
- *
- * @param nm the {@code String} to decode.
- * @return an {@code Integer} object holding the {@code int}
- * value represented by {@code nm}
- * @exception NumberFormatException if the {@code String} does not
- * contain a parsable integer.
- * @see java.lang.Integer#parseInt(java.lang.String, int)
- */
- public static Integer decode(String nm) throws NumberFormatException {
- int radix = 10;
- int index = 0;
- boolean negative = false;
- Integer result;
-
- if (nm.length() == 0)
- throw new NumberFormatException("Zero length string");
- char firstChar = nm.charAt(0);
- // Handle sign, if present
- if (firstChar == '-') {
- negative = true;
- index++;
- } else if (firstChar == '+')
- index++;
-
- // Handle radix specifier, if present
- if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
- index += 2;
- radix = 16;
- }
- else if (nm.startsWith("#", index)) {
- index ++;
- radix = 16;
- }
- else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
- index ++;
- radix = 8;
- }
-
- if (nm.startsWith("-", index) || nm.startsWith("+", index))
- throw new NumberFormatException("Sign character in wrong position");
-
- try {
- result = Integer.valueOf(nm.substring(index), radix);
- result = negative ? Integer.valueOf(-result.intValue()) : result;
- } catch (NumberFormatException e) {
- // If number is Integer.MIN_VALUE, we'll end up here. The next line
- // handles this case, and causes any genuine format error to be
- // rethrown.
- String constant = negative ? ("-" + nm.substring(index))
- : nm.substring(index);
- result = Integer.valueOf(constant, radix);
- }
- return result;
- }
-
- /**
- * Compares two {@code Integer} objects numerically.
- *
- * @param anotherInteger the {@code Integer} to be compared.
- * @return the value {@code 0} if this {@code Integer} is
- * equal to the argument {@code Integer}; a value less than
- * {@code 0} if this {@code Integer} is numerically less
- * than the argument {@code Integer}; and a value greater
- * than {@code 0} if this {@code Integer} is numerically
- * greater than the argument {@code Integer} (signed
- * comparison).
- * @since 1.2
- */
- public int compareTo(Integer anotherInteger) {
- return compare(this.value, anotherInteger.value);
- }
-
- /**
- * Compares two {@code int} values numerically.
- * The value returned is identical to what would be returned by:
- * Note that this method is closely related to the logarithm base 2.
- * For all positive {@code int} values x:
- * Note that left rotation with a negative distance is equivalent to
- * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
- * distance)}. Note also that rotation by any multiple of 32 is a
- * no-op, so all but the last five bits of the rotation distance can be
- * ignored, even if the distance is negative: {@code rotateLeft(val,
- * distance) == rotateLeft(val, distance & 0x1F)}.
- *
- * @return the value obtained by rotating the two's complement binary
- * representation of the specified {@code int} value left by the
- * specified number of bits.
- * @since 1.5
- */
- public static int rotateLeft(int i, int distance) {
- return (i << distance) | (i >>> -distance);
- }
-
- /**
- * Returns the value obtained by rotating the two's complement binary
- * representation of the specified {@code int} value right by the
- * specified number of bits. (Bits shifted out of the right hand, or
- * low-order, side reenter on the left, or high-order.)
- *
- * Note that right rotation with a negative distance is equivalent to
- * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
- * distance)}. Note also that rotation by any multiple of 32 is a
- * no-op, so all but the last five bits of the rotation distance can be
- * ignored, even if the distance is negative: {@code rotateRight(val,
- * distance) == rotateRight(val, distance & 0x1F)}.
- *
- * @return the value obtained by rotating the two's complement binary
- * representation of the specified {@code int} value right by the
- * specified number of bits.
- * @since 1.5
- */
- public static int rotateRight(int i, int distance) {
- return (i >>> distance) | (i << -distance);
- }
-
- /**
- * Returns the value obtained by reversing the order of the bits in the
- * two's complement binary representation of the specified {@code int}
- * value.
- *
- * @return the value obtained by reversing order of the bits in the
- * specified {@code int} value.
- * @since 1.5
- */
- public static int reverse(int i) {
- // HD, Figure 7-1
- i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
- i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333;
- i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
- i = (i << 24) | ((i & 0xff00) << 8) |
- ((i >>> 8) & 0xff00) | (i >>> 24);
- return i;
- }
-
- /**
- * Returns the signum function of the specified {@code int} value. (The
- * return value is -1 if the specified value is negative; 0 if the
- * specified value is zero; and 1 if the specified value is positive.)
- *
- * @return the signum function of the specified {@code int} value.
- * @since 1.5
- */
- public static int signum(int i) {
- // HD, Section 2-7
- return (i >> 31) | (-i >>> 31);
- }
-
- /**
- * Returns the value obtained by reversing the order of the bytes in the
- * two's complement representation of the specified {@code int} value.
- *
- * @return the value obtained by reversing the bytes in the specified
- * {@code int} value.
- * @since 1.5
- */
- public static int reverseBytes(int i) {
- return ((i >>> 24) ) |
- ((i >> 8) & 0xFF00) |
- ((i << 8) & 0xFF0000) |
- ((i << 24));
- }
-
- /** use serialVersionUID from JDK 1.0.2 for interoperability */
- private static final long serialVersionUID = 1360826667806852920L;
-}
'\u002D'). If the first argument is not
- * negative, no sign character appears in the result.
- *
- * '\u0030'); otherwise, the first character of
- * the representation of the magnitude will not be the zero
- * character. The following ASCII characters are used as digits:
- *
- *
- * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
- *
- *
- * These are '\u0030' through
- * '\u0039' and '\u0061' through
- * '\u007A'. If {@code radix} is
- * N, then the first N of these characters
- * are used as radix-N digits in the order shown. Thus,
- * the digits for hexadecimal (radix 16) are
- * {@code 0123456789abcdef}. If uppercase letters are
- * desired, the {@link java.lang.String#toUpperCase()} method may
- * be called on the result:
- *
- *
- * {@code Integer.toString(n, 16).toUpperCase()}
- *
- *
- * @param i an integer to be converted to a string.
- * @param radix the radix to use in the string representation.
- * @return a string representation of the argument in the specified radix.
- * @see java.lang.Character#MAX_RADIX
- * @see java.lang.Character#MIN_RADIX
- */
- public static String toString(int i, int radix) {
-
- if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
- radix = 10;
-
- /* Use the faster version */
- if (radix == 10) {
- return toString(i);
- }
-
- char buf[] = new char[33];
- boolean negative = (i < 0);
- int charPos = 32;
-
- if (!negative) {
- i = -i;
- }
-
- while (i <= -radix) {
- buf[charPos--] = digits[-(i % radix)];
- i = i / radix;
- }
- buf[charPos] = digits[-i];
-
- if (negative) {
- buf[--charPos] = '-';
- }
-
- return new String(buf, charPos, (33 - charPos));
- }
-
- /**
- * Returns a string representation of the integer argument as an
- * unsigned integer in base 16.
- *
- * '\u0030'); otherwise, the first character of
- * the representation of the unsigned magnitude will not be the
- * zero character. The following characters are used as
- * hexadecimal digits:
- *
- *
- * {@code 0123456789abcdef}
- *
- *
- * These are the characters '\u0030' through
- * '\u0039' and '\u0061' through
- * '\u0066'. If uppercase letters are
- * desired, the {@link java.lang.String#toUpperCase()} method may
- * be called on the result:
- *
- *
- * {@code Integer.toHexString(n).toUpperCase()}
- *
- *
- * @param i an integer to be converted to a string.
- * @return the string representation of the unsigned integer value
- * represented by the argument in hexadecimal (base 16).
- * @since JDK1.0.2
- */
- public static String toHexString(int i) {
- return toUnsignedString(i, 4);
- }
-
- /**
- * Returns a string representation of the integer argument as an
- * unsigned integer in base 8.
- *
- * '\u0030'); otherwise, the first character of
- * the representation of the unsigned magnitude will not be the
- * zero character. The following characters are used as octal
- * digits:
- *
- *
- * {@code 01234567}
- *
- *
- * These are the characters '\u0030' through
- * '\u0037'.
- *
- * @param i an integer to be converted to a string.
- * @return the string representation of the unsigned integer value
- * represented by the argument in octal (base 8).
- * @since JDK1.0.2
- */
- public static String toOctalString(int i) {
- return toUnsignedString(i, 3);
- }
-
- /**
- * Returns a string representation of the integer argument as an
- * unsigned integer in base 2.
- *
- * '\u0030'); otherwise, the first character of
- * the representation of the unsigned magnitude will not be the
- * zero character. The characters {@code '0'}
- * ('\u0030') and {@code '1'}
- * ('\u0031') are used as binary digits.
- *
- * @param i an integer to be converted to a string.
- * @return the string representation of the unsigned integer value
- * represented by the argument in binary (base 2).
- * @since JDK1.0.2
- */
- public static String toBinaryString(int i) {
- return toUnsignedString(i, 1);
- }
-
- /**
- * Convert the integer to an unsigned number.
- */
- private static String toUnsignedString(int i, int shift) {
- char[] buf = new char[32];
- int charPos = 32;
- int radix = 1 << shift;
- int mask = radix - 1;
- do {
- buf[--charPos] = digits[i & mask];
- i >>>= shift;
- } while (i != 0);
-
- return new String(buf, charPos, (32 - charPos));
- }
-
-
- final static char [] DigitTens = {
- '0', '0', '0', '0', '0', '0', '0', '0', '0', '0',
- '1', '1', '1', '1', '1', '1', '1', '1', '1', '1',
- '2', '2', '2', '2', '2', '2', '2', '2', '2', '2',
- '3', '3', '3', '3', '3', '3', '3', '3', '3', '3',
- '4', '4', '4', '4', '4', '4', '4', '4', '4', '4',
- '5', '5', '5', '5', '5', '5', '5', '5', '5', '5',
- '6', '6', '6', '6', '6', '6', '6', '6', '6', '6',
- '7', '7', '7', '7', '7', '7', '7', '7', '7', '7',
- '8', '8', '8', '8', '8', '8', '8', '8', '8', '8',
- '9', '9', '9', '9', '9', '9', '9', '9', '9', '9',
- } ;
-
- final static char [] DigitOnes = {
- '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
- '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
- '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
- '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
- '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
- '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
- '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
- '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
- '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
- '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
- } ;
-
- // I use the "invariant division by multiplication" trick to
- // accelerate Integer.toString. In particular we want to
- // avoid division by 10.
- //
- // The "trick" has roughly the same performance characteristics
- // as the "classic" Integer.toString code on a non-JIT VM.
- // The trick avoids .rem and .div calls but has a longer code
- // path and is thus dominated by dispatch overhead. In the
- // JIT case the dispatch overhead doesn't exist and the
- // "trick" is considerably faster than the classic code.
- //
- // TODO-FIXME: convert (x * 52429) into the equiv shift-add
- // sequence.
- //
- // RE: Division by Invariant Integers using Multiplication
- // T Gralund, P Montgomery
- // ACM PLDI 1994
- //
-
- /**
- * Returns a {@code String} object representing the
- * specified integer. The argument is converted to signed decimal
- * representation and returned as a string, exactly as if the
- * argument and radix 10 were given as arguments to the {@link
- * #toString(int, int)} method.
- *
- * @param i an integer to be converted.
- * @return a string representation of the argument in base 10.
- */
- @JavaScriptBody(args = "i", body = "return i.toString();")
- public static String toString(int i) {
- if (i == Integer.MIN_VALUE)
- return "-2147483648";
- int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
- char[] buf = new char[size];
- getChars(i, size, buf);
- return new String(buf, 0, size);
- }
-
- /**
- * Places characters representing the integer i into the
- * character array buf. The characters are placed into
- * the buffer backwards starting with the least significant
- * digit at the specified index (exclusive), and working
- * backwards from there.
- *
- * Will fail if i == Integer.MIN_VALUE
- */
- static void getChars(int i, int index, char[] buf) {
- int q, r;
- int charPos = index;
- char sign = 0;
-
- if (i < 0) {
- sign = '-';
- i = -i;
- }
-
- // Generate two digits per iteration
- while (i >= 65536) {
- q = i / 100;
- // really: r = i - (q * 100);
- r = i - ((q << 6) + (q << 5) + (q << 2));
- i = q;
- buf [--charPos] = DigitOnes[r];
- buf [--charPos] = DigitTens[r];
- }
-
- // Fall thru to fast mode for smaller numbers
- // assert(i <= 65536, i);
- for (;;) {
- q = (i * 52429) >>> (16+3);
- r = i - ((q << 3) + (q << 1)); // r = i-(q*10) ...
- buf [--charPos] = digits [r];
- i = q;
- if (i == 0) break;
- }
- if (sign != 0) {
- buf [--charPos] = sign;
- }
- }
-
- final static int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
- 99999999, 999999999, Integer.MAX_VALUE };
-
- // Requires positive x
- static int stringSize(int x) {
- for (int i=0; ; i++)
- if (x <= sizeTable[i])
- return i+1;
- }
-
- /**
- * Parses the string argument as a signed integer in the radix
- * specified by the second argument. The characters in the string
- * must all be digits of the specified radix (as determined by
- * whether {@link java.lang.Character#digit(char, int)} returns a
- * nonnegative value), except that the first character may be an
- * ASCII minus sign {@code '-'} ('\u002D') to
- * indicate a negative value or an ASCII plus sign {@code '+'}
- * ('\u002B') to indicate a positive value. The
- * resulting integer value is returned.
- *
- *
- *
- *
- * '\u002D') or plus sign
- * {@code '+'} ('\u002B') provided that the
- * string is longer than length 1.
- *
- *
- *
- * @param s the {@code String} containing the integer
- * representation to be parsed
- * @param radix the radix to be used while parsing {@code s}.
- * @return the integer represented by the string argument in the
- * specified radix.
- * @exception NumberFormatException if the {@code String}
- * does not contain a parsable {@code int}.
- */
- @JavaScriptBody(args={"s", "radix"}, body="return parseInt(s,radix);")
- public static int parseInt(String s, int radix)
- throws NumberFormatException
- {
- /*
- * WARNING: This method may be invoked early during VM initialization
- * before IntegerCache is initialized. Care must be taken to not use
- * the valueOf method.
- */
-
- if (s == null) {
- throw new NumberFormatException("null");
- }
-
- if (radix < Character.MIN_RADIX) {
- throw new NumberFormatException("radix " + radix +
- " less than Character.MIN_RADIX");
- }
-
- if (radix > Character.MAX_RADIX) {
- throw new NumberFormatException("radix " + radix +
- " greater than Character.MAX_RADIX");
- }
-
- int result = 0;
- boolean negative = false;
- int i = 0, len = s.length();
- int limit = -Integer.MAX_VALUE;
- int multmin;
- int digit;
-
- if (len > 0) {
- char firstChar = s.charAt(0);
- if (firstChar < '0') { // Possible leading "+" or "-"
- if (firstChar == '-') {
- negative = true;
- limit = Integer.MIN_VALUE;
- } else if (firstChar != '+')
- throw NumberFormatException.forInputString(s);
-
- if (len == 1) // Cannot have lone "+" or "-"
- throw NumberFormatException.forInputString(s);
- i++;
- }
- multmin = limit / radix;
- while (i < len) {
- // Accumulating negatively avoids surprises near MAX_VALUE
- digit = Character.digit(s.charAt(i++),radix);
- if (digit < 0) {
- throw NumberFormatException.forInputString(s);
- }
- if (result < multmin) {
- throw NumberFormatException.forInputString(s);
- }
- result *= radix;
- if (result < limit + digit) {
- throw NumberFormatException.forInputString(s);
- }
- result -= digit;
- }
- } else {
- throw NumberFormatException.forInputString(s);
- }
- return negative ? result : -result;
- }
-
- /**
- * Parses the string argument as a signed decimal integer. The
- * characters in the string must all be decimal digits, except
- * that the first character may be an ASCII minus sign {@code '-'}
- * (
- * parseInt("0", 10) returns 0
- * parseInt("473", 10) returns 473
- * parseInt("+42", 10) returns 42
- * parseInt("-0", 10) returns 0
- * parseInt("-FF", 16) returns -255
- * parseInt("1100110", 2) returns 102
- * parseInt("2147483647", 10) returns 2147483647
- * parseInt("-2147483648", 10) returns -2147483648
- * parseInt("2147483648", 10) throws a NumberFormatException
- * parseInt("99", 8) throws a NumberFormatException
- * parseInt("Kona", 10) throws a NumberFormatException
- * parseInt("Kona", 27) returns 411787
- * '\u002D') to indicate a negative value or an
- * ASCII plus sign {@code '+'} ('\u002B') to
- * indicate a positive value. The resulting integer value is
- * returned, exactly as if the argument and the radix 10 were
- * given as arguments to the {@link #parseInt(java.lang.String,
- * int)} method.
- *
- * @param s a {@code String} containing the {@code int}
- * representation to be parsed
- * @return the integer value represented by the argument in decimal.
- * @exception NumberFormatException if the string does not contain a
- * parsable integer.
- */
- public static int parseInt(String s) throws NumberFormatException {
- return parseInt(s,10);
- }
-
- /**
- * Returns an {@code Integer} object holding the value
- * extracted from the specified {@code String} when parsed
- * with the radix given by the second argument. The first argument
- * is interpreted as representing a signed integer in the radix
- * specified by the second argument, exactly as if the arguments
- * were given to the {@link #parseInt(java.lang.String, int)}
- * method. The result is an {@code Integer} object that
- * represents the integer value specified by the string.
- *
- *
- * {@code new Integer(Integer.parseInt(s, radix))}
- *
- *
- * @param s the string to be parsed.
- * @param radix the radix to be used in interpreting {@code s}
- * @return an {@code Integer} object holding the value
- * represented by the string argument in the specified
- * radix.
- * @exception NumberFormatException if the {@code String}
- * does not contain a parsable {@code int}.
- */
- public static Integer valueOf(String s, int radix) throws NumberFormatException {
- return Integer.valueOf(parseInt(s,radix));
- }
-
- /**
- * Returns an {@code Integer} object holding the
- * value of the specified {@code String}. The argument is
- * interpreted as representing a signed decimal integer, exactly
- * as if the argument were given to the {@link
- * #parseInt(java.lang.String)} method. The result is an
- * {@code Integer} object that represents the integer value
- * specified by the string.
- *
- *
- * {@code new Integer(Integer.parseInt(s))}
- *
- *
- * @param s the string to be parsed.
- * @return an {@code Integer} object holding the value
- * represented by the string argument.
- * @exception NumberFormatException if the string cannot be parsed
- * as an integer.
- */
- public static Integer valueOf(String s) throws NumberFormatException {
- return Integer.valueOf(parseInt(s, 10));
- }
-
- /**
- * Cache to support the object identity semantics of autoboxing for values between
- * -128 and 127 (inclusive) as required by JLS.
- *
- * The cache is initialized on first usage. The size of the cache
- * may be controlled by the -XX:AutoBoxCacheMax=
- * {@code getInteger(nm, null)}
- *
- *
- * @param nm property name.
- * @return the {@code Integer} value of the property.
- * @see java.lang.System#getProperty(java.lang.String)
- * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
- */
- public static Integer getInteger(String nm) {
- return getInteger(nm, null);
- }
-
- /**
- * Determines the integer value of the system property with the
- * specified name.
- *
- *
- * {@code getInteger(nm, new Integer(val))}
- *
- *
- * but in practice it may be implemented in a manner such as:
- *
- *
- *
- * to avoid the unnecessary allocation of an {@code Integer}
- * object when the default value is not needed.
- *
- * @param nm property name.
- * @param val default value.
- * @return the {@code Integer} value of the property.
- * @see java.lang.System#getProperty(java.lang.String)
- * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
- */
- public static Integer getInteger(String nm, int val) {
- Integer result = getInteger(nm, null);
- return (result == null) ? Integer.valueOf(val) : result;
- }
-
- /**
- * Returns the integer value of the system property with the
- * specified name. The first argument is treated as the name of a
- * system property. System properties are accessible through the
- * {@link java.lang.System#getProperty(java.lang.String)} method.
- * The string value of this property is then interpreted as an
- * integer value, as per the {@code Integer.decode} method,
- * and an {@code Integer} object representing this value is
- * returned.
- *
- *
- * Integer result = getInteger(nm, null);
- * return (result == null) ? new Integer(val) : result;
- *
- *
- *
- *
- *
- * DecimalNumeral, HexDigits, and OctalDigits
- * are as defined in section 3.10.1 of
- * The Java™ Language Specification,
- * except that underscores are not accepted between digits.
- *
- *
- *
- *
- * Integer.valueOf(x).compareTo(Integer.valueOf(y))
- *
- *
- * @param x the first {@code int} to compare
- * @param y the second {@code int} to compare
- * @return the value {@code 0} if {@code x == y};
- * a value less than {@code 0} if {@code x < y}; and
- * a value greater than {@code 0} if {@code x > y}
- * @since 1.7
- */
- public static int compare(int x, int y) {
- return (x < y) ? -1 : ((x == y) ? 0 : 1);
- }
-
-
- // Bit twiddling
-
- /**
- * The number of bits used to represent an {@code int} value in two's
- * complement binary form.
- *
- * @since 1.5
- */
- public static final int SIZE = 32;
-
- /**
- * Returns an {@code int} value with at most a single one-bit, in the
- * position of the highest-order ("leftmost") one-bit in the specified
- * {@code int} value. Returns zero if the specified value has no
- * one-bits in its two's complement binary representation, that is, if it
- * is equal to zero.
- *
- * @return an {@code int} value with a single one-bit, in the position
- * of the highest-order one-bit in the specified value, or zero if
- * the specified value is itself equal to zero.
- * @since 1.5
- */
- public static int highestOneBit(int i) {
- // HD, Figure 3-1
- i |= (i >> 1);
- i |= (i >> 2);
- i |= (i >> 4);
- i |= (i >> 8);
- i |= (i >> 16);
- return i - (i >>> 1);
- }
-
- /**
- * Returns an {@code int} value with at most a single one-bit, in the
- * position of the lowest-order ("rightmost") one-bit in the specified
- * {@code int} value. Returns zero if the specified value has no
- * one-bits in its two's complement binary representation, that is, if it
- * is equal to zero.
- *
- * @return an {@code int} value with a single one-bit, in the position
- * of the lowest-order one-bit in the specified value, or zero if
- * the specified value is itself equal to zero.
- * @since 1.5
- */
- public static int lowestOneBit(int i) {
- // HD, Section 2-1
- return i & -i;
- }
-
- /**
- * Returns the number of zero bits preceding the highest-order
- * ("leftmost") one-bit in the two's complement binary representation
- * of the specified {@code int} value. Returns 32 if the
- * specified value has no one-bits in its two's complement representation,
- * in other words if it is equal to zero.
- *
- *
- *
- *
- * @return the number of zero bits preceding the highest-order
- * ("leftmost") one-bit in the two's complement binary representation
- * of the specified {@code int} value, or 32 if the value
- * is equal to zero.
- * @since 1.5
- */
- public static int numberOfLeadingZeros(int i) {
- // HD, Figure 5-6
- if (i == 0)
- return 32;
- int n = 1;
- if (i >>> 16 == 0) { n += 16; i <<= 16; }
- if (i >>> 24 == 0) { n += 8; i <<= 8; }
- if (i >>> 28 == 0) { n += 4; i <<= 4; }
- if (i >>> 30 == 0) { n += 2; i <<= 2; }
- n -= i >>> 31;
- return n;
- }
-
- /**
- * Returns the number of zero bits following the lowest-order ("rightmost")
- * one-bit in the two's complement binary representation of the specified
- * {@code int} value. Returns 32 if the specified value has no
- * one-bits in its two's complement representation, in other words if it is
- * equal to zero.
- *
- * @return the number of zero bits following the lowest-order ("rightmost")
- * one-bit in the two's complement binary representation of the
- * specified {@code int} value, or 32 if the value is equal
- * to zero.
- * @since 1.5
- */
- public static int numberOfTrailingZeros(int i) {
- // HD, Figure 5-14
- int y;
- if (i == 0) return 32;
- int n = 31;
- y = i <<16; if (y != 0) { n = n -16; i = y; }
- y = i << 8; if (y != 0) { n = n - 8; i = y; }
- y = i << 4; if (y != 0) { n = n - 4; i = y; }
- y = i << 2; if (y != 0) { n = n - 2; i = y; }
- return n - ((i << 1) >>> 31);
- }
-
- /**
- * Returns the number of one-bits in the two's complement binary
- * representation of the specified {@code int} value. This function is
- * sometimes referred to as the population count.
- *
- * @return the number of one-bits in the two's complement binary
- * representation of the specified {@code int} value.
- * @since 1.5
- */
- public static int bitCount(int i) {
- // HD, Figure 5-2
- i = i - ((i >>> 1) & 0x55555555);
- i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
- i = (i + (i >>> 4)) & 0x0f0f0f0f;
- i = i + (i >>> 8);
- i = i + (i >>> 16);
- return i & 0x3f;
- }
-
- /**
- * Returns the value obtained by rotating the two's complement binary
- * representation of the specified {@code int} value left by the
- * specified number of bits. (Bits shifted out of the left hand, or
- * high-order, side reenter on the right, or low-order.)
- *
- *