Class Integer

Method Details

• toString

  public static String toString(int i, int radix)

  Returns a string representation of the first argument in the radix specified by the second argument.

  If the radix is smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX, then the radix 10 is used instead.

  If the first argument is negative, the first element of the result is the ASCII minus character '-' ('\u002D'). If the first argument is not negative, no sign character appears in the result.

  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 '0' ('\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:

  0123456789abcdefghijklmnopqrstuvwxyz

  These are '\u0030' through '\u0039' and '\u0061' through '\u007A'. If 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 0123456789abcdef. If uppercase letters are desired, the String.toUpperCase() method may be called on the result:

  Integer.toString(n, 16).toUpperCase()

  Parameters:

  i - an integer to be converted to a string.

  radix - the radix to use in the string representation.

  Returns:

  a string representation of the argument in the specified radix.

  See Also:

  • Character.MAX_RADIX
  • Character.MIN_RADIX

• toUnsignedString

  public static String toUnsignedString(int i, int radix)

  Returns a string representation of the first argument as an unsigned integer value in the radix specified by the second argument.

  If the radix is smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX, then the radix 10 is used instead.

  Note that since the first argument is treated as an unsigned value, no leading sign character is printed.

  If the magnitude is zero, it is represented by a single zero character '0' ('\u0030'); otherwise, the first character of the representation of the magnitude will not be the zero character.

  The behavior of radixes and the characters used as digits are the same as toString.

  Parameters:

  i - an integer to be converted to an unsigned string.

  radix - the radix to use in the string representation.

  Returns:

  an unsigned string representation of the argument in the specified radix.

  Since:

  1.8

  See Also:

  • toString(int, int)

• toHexString

  public static String toHexString(int i)

  Returns a string representation of the integer argument as an unsigned integer in base 16.

  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 0s.

  The value of the argument can be recovered from the returned string s by calling Integer.parseUnsignedInt(s, 16).

  If the unsigned magnitude is zero, it is represented by a single zero character '0' ('\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:

  0123456789abcdef

  These are the characters '\u0030' through '\u0039' and '\u0061' through '\u0066'. If uppercase letters are desired, the String.toUpperCase() method may be called on the result:

  Integer.toHexString(n).toUpperCase()

  API Note:

  The HexFormat class provides formatting and parsing of byte arrays and primitives to return a string or adding to an Appendable. HexFormat formats and parses uppercase or lowercase hexadecimal characters, with leading zeros and for byte arrays includes for each byte a delimiter, prefix, and suffix.

  Parameters:

  i - an integer to be converted to a string.

  Returns:

  the string representation of the unsigned integer value represented by the argument in hexadecimal (base 16).

  Since:

  1.0.2

  See Also:

  • HexFormat
  • parseUnsignedInt(String, int)
  • toUnsignedString(int, int)

• toOctalString

  public static String toOctalString(int i)

  Returns a string representation of the integer argument as an unsigned integer in base 8.

  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 0s.

  The value of the argument can be recovered from the returned string s by calling Integer.parseUnsignedInt(s, 8).

  If the unsigned magnitude is zero, it is represented by a single zero character '0' ('\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:

  01234567

  These are the characters '\u0030' through '\u0037'.

  Parameters:

  i - an integer to be converted to a string.

  Returns:

  the string representation of the unsigned integer value represented by the argument in octal (base 8).

  Since:

  1.0.2

  See Also:

  • parseUnsignedInt(String, int)
  • toUnsignedString(int, int)

• toBinaryString

  public static String toBinaryString(int i)

  Returns a string representation of the integer argument as an unsigned integer in base 2.

  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 0s.

  The value of the argument can be recovered from the returned string s by calling Integer.parseUnsignedInt(s, 2).

  If the unsigned magnitude is zero, it is represented by a single zero character '0' ('\u0030'); otherwise, the first character of the representation of the unsigned magnitude will not be the zero character. The characters '0' ('\u0030') and '1' ('\u0031') are used as binary digits.

  Parameters:

  i - an integer to be converted to a string.

  Returns:

  the string representation of the unsigned integer value represented by the argument in binary (base 2).

  Since:

  1.0.2

  See Also:

  • parseUnsignedInt(String, int)
  • toUnsignedString(int, int)

• toString

  public static String toString(int i)

  Returns a 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 toString(int, int) method.

  Parameters:

  i - an integer to be converted.

  Returns:

  a string representation of the argument in base 10.

• toUnsignedString

  public static String toUnsignedString(int i)

  Returns a string representation of the argument as an unsigned decimal value. The argument is converted to unsigned decimal representation and returned as a string exactly as if the argument and radix 10 were given as arguments to the toUnsignedString(int, int) method.

  Parameters:

  i - an integer to be converted to an unsigned string.

  Returns:

  an unsigned string representation of the argument.

  Since:

  1.8

  See Also:

  • toUnsignedString(int, int)

• parseInt

  public static int parseInt(String s, int radix) throws NumberFormatException

  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 Character.digit(char, int) returns a nonnegative value), except that the first character may be an ASCII minus sign '-' ('\u002D') to indicate a negative value or an ASCII plus sign '+' ('\u002B') to indicate a positive value. The resulting integer value is returned.

  An exception of type NumberFormatException is thrown if any of the following situations occurs:

  • The first argument is null or is a string of length zero.
  • The radix is either smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX.
  • Any character of the string is not a digit of the specified radix, except that the first character may be a minus sign '-' ('\u002D') or plus sign '+' ('\u002B') provided that the string is longer than length 1.
  • The value represented by the string is not a value of type int.

  Examples:

   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
   

  Parameters:

  s - the String containing the integer representation to be parsed

  radix - the radix to be used while parsing s.

  Returns:

  the integer represented by the string argument in the specified radix.

  Throws:

  NumberFormatException - if the String does not contain a parsable int.

• parseInt

  public static int parseInt(CharSequence s, int beginIndex, int endIndex, int radix) throws NumberFormatException

  Parses the CharSequence argument as a signed int in the specified radix, beginning at the specified beginIndex and extending to endIndex - 1.

  The method does not take steps to guard against the CharSequence being mutated while parsing.

  Parameters:

  s - the CharSequence containing the int representation to be parsed

  beginIndex - the beginning index, inclusive.

  endIndex - the ending index, exclusive.

  radix - the radix to be used while parsing s.

  Returns:

  the signed int represented by the subsequence in the specified radix.

  Throws:

  NullPointerException - if s is null.

  IndexOutOfBoundsException - if beginIndex is negative, or if beginIndex is greater than endIndex or if endIndex is greater than s.length().

  NumberFormatException - if the CharSequence does not contain a parsable int in the specified radix, or if radix is either smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX.

  Since:

  9

• parseInt

  public static int parseInt(String s) throws NumberFormatException

  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 '-' ('\u002D') to indicate a negative value or an ASCII plus sign '+' ('\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 parseInt(java.lang.String, int) method.

  Parameters:

  s - a String containing the int representation to be parsed

  Returns:

  the integer value represented by the argument in decimal.

  Throws:

  NumberFormatException - if the string does not contain a parsable integer.

• parseUnsignedInt

  public static int parseUnsignedInt(String s, int radix) throws NumberFormatException

  Parses the string argument as an unsigned integer in the radix specified by the second argument. An unsigned integer maps the values usually associated with negative numbers to positive numbers larger than MAX_VALUE. The characters in the string must all be digits of the specified radix (as determined by whether Character.digit(char, int) returns a nonnegative value), except that the first character may be an ASCII plus sign '+' ('\u002B'). The resulting integer value is returned.

  An exception of type NumberFormatException is thrown if any of the following situations occurs:

  • The first argument is null or is a string of length zero.
  • The radix is either smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX.
  • Any character of the string is not a digit of the specified radix, except that the first character may be a plus sign '+' ('\u002B') provided that the string is longer than length 1.
  • The value represented by the string is larger than the largest unsigned int, 2³²-1.

  Parameters:

  s - the String containing the unsigned integer representation to be parsed

  radix - the radix to be used while parsing s.

  Returns:

  the integer represented by the string argument in the specified radix.

  Throws:

  NumberFormatException - if the String does not contain a parsable int.

  Since:

  1.8

• parseUnsignedInt

  public static int parseUnsignedInt(CharSequence s, int beginIndex, int endIndex, int radix) throws NumberFormatException

  Parses the CharSequence argument as an unsigned int in the specified radix, beginning at the specified beginIndex and extending to endIndex - 1.

  The method does not take steps to guard against the CharSequence being mutated while parsing.

  Parameters:

  s - the CharSequence containing the unsigned int representation to be parsed

  beginIndex - the beginning index, inclusive.

  endIndex - the ending index, exclusive.

  radix - the radix to be used while parsing s.

  Returns:

  the unsigned int represented by the subsequence in the specified radix.

  Throws:

  NullPointerException - if s is null.

  IndexOutOfBoundsException - if beginIndex is negative, or if beginIndex is greater than endIndex or if endIndex is greater than s.length().

  NumberFormatException - if the CharSequence does not contain a parsable unsigned int in the specified radix, or if radix is either smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX.

  Since:

  9

• parseUnsignedInt

  public static int parseUnsignedInt(String s) throws NumberFormatException

  Parses the string argument as an unsigned decimal integer. The characters in the string must all be decimal digits, except that the first character may be an ASCII plus sign '+' ('\u002B'). The resulting integer value is returned, exactly as if the argument and the radix 10 were given as arguments to the parseUnsignedInt(java.lang.String, int) method.

  Parameters:

  s - a String containing the unsigned int representation to be parsed

  Returns:

  the unsigned integer value represented by the argument in decimal.

  Throws:

  NumberFormatException - if the string does not contain a parsable unsigned integer.

  Since:

  1.8

• valueOf

  public static Integer valueOf(String s, int radix) throws NumberFormatException

  Returns an Integer object holding the value extracted from the specified 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 parseInt(java.lang.String, int) method. The result is an Integer object that represents the integer value specified by the string.

  In other words, this method returns an Integer object equal to the value of:

  Integer.valueOf(Integer.parseInt(s, radix))

  Parameters:

  s - the string to be parsed.

  radix - the radix to be used in interpreting s

  Returns:

  an Integer object holding the value represented by the string argument in the specified radix.

  Throws:

  NumberFormatException - if the String does not contain a parsable int.

• valueOf

  public static Integer valueOf(String s) throws NumberFormatException

  Returns an Integer object holding the value of the specified String. The argument is interpreted as representing a signed decimal integer, exactly as if the argument were given to the parseInt(java.lang.String) method. The result is an Integer object that represents the integer value specified by the string.

  In other words, this method returns an Integer object equal to the value of:

  Integer.valueOf(Integer.parseInt(s))

  Parameters:

  s - the string to be parsed.

  Returns:

  an Integer object holding the value represented by the string argument.

  Throws:

  NumberFormatException - if the string cannot be parsed as an integer.

• valueOf

  public static Integer valueOf(int i)

  Returns an Integer instance representing the specified int value. If a new Integer instance is not required, this method should generally be used in preference to the constructor Integer(int), as this method is likely to yield significantly better space and time performance by caching frequently requested values. This method will always cache values in the range -128 to 127, inclusive, and may cache other values outside of this range.

  Parameters:

  i - an int value.

  Returns:

  an Integer instance representing i.

  Since:

  1.5

• byteValue

  public byte byteValue()

  Returns the value of this Integer as a byte after a narrowing primitive conversion.

  Overrides:

  byteValue in class Number

  Returns:

  the numeric value represented by this object after conversion to type byte.

  See Java Language Specification:

  5.1.3 Narrowing Primitive Conversion
  

• shortValue

  public short shortValue()

  Returns the value of this Integer as a short after a narrowing primitive conversion.

  Overrides:

  shortValue in class Number

  Returns:

  the numeric value represented by this object after conversion to type short.

  See Java Language Specification:

  5.1.3 Narrowing Primitive Conversion
  

• intValue

  public int intValue()

  Returns the value of this Integer as an int.

  Specified by:

  intValue in class Number

  Returns:

  the numeric value represented by this object after conversion to type int.

• longValue

  public long longValue()

  Returns the value of this Integer as a long after a widening primitive conversion.

  Specified by:

  longValue in class Number

  Returns:

  the numeric value represented by this object after conversion to type long.

  See Java Language Specification:

  5.1.2 Widening Primitive Conversion
  

  See Also:

  • toUnsignedLong(int)

• floatValue

  public float floatValue()

  Returns the value of this Integer as a float after a widening primitive conversion.

  Specified by:

  floatValue in class Number

  Returns:

  the numeric value represented by this object after conversion to type float.

  See Java Language Specification:

  5.1.2 Widening Primitive Conversion
  

• doubleValue

  public double doubleValue()

  Returns the value of this Integer as a double after a widening primitive conversion.

  Specified by:

  doubleValue in class Number

  Returns:

  the numeric value represented by this object after conversion to type double.

  See Java Language Specification:

  5.1.2 Widening Primitive Conversion
  

• toString

  public String toString()

  Returns a String object representing this Integer's value. The value is converted to signed decimal representation and returned as a string, exactly as if the integer value were given as an argument to the toString(int) method.

  Overrides:

  toString in class Object

  Returns:

  a string representation of the value of this object in base 10.

• hashCode

  public int hashCode()

  Returns a hash code for this Integer.

  Overrides:

  hashCode in class Object

  Returns:

  a hash code value for this object, equal to the primitive int value represented by this Integer object.

  See Also:

  • Object.equals(java.lang.Object)
  • System.identityHashCode(java.lang.Object)

• hashCode

  public static int hashCode(int value)

  Returns a hash code for an int value; compatible with Integer.hashCode().

  Parameters:

  value - the value to hash

  Returns:

  a hash code value for an int value.

  Since:

  1.8

• equals

  public boolean equals(Object obj)

  Compares this object to the specified object. The result is true if and only if the argument is not null and is an Integer object that contains the same int value as this object.

  Overrides:

  equals in class Object

  Parameters:

  obj - the object to compare with.

  Returns:

  true if the objects are the same; false otherwise.

  See Also:

  • Object.hashCode()
  • HashMap

• getInteger

  public static Integer getInteger(String nm)

  Determines 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 System.getProperty(java.lang.String) method. The string value of this property is then interpreted as an integer value using the grammar supported by decode and an Integer object representing this value is returned.

  If there is no property with the specified name, if the specified name is empty or null, or if the property does not have the correct numeric format, then null is returned.

  In other words, this method returns an Integer object equal to the value of:

  getInteger(nm, null)

  Parameters:

  nm - property name.

  Returns:

  the Integer value of the property.

  Throws:

  SecurityException - for the same reasons as System.getProperty

  See Also:

  • System.getProperty(java.lang.String)
  • System.getProperty(java.lang.String, java.lang.String)

• getInteger

  public static Integer getInteger(String nm, int val)

  Determines 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 System.getProperty(java.lang.String) method. The string value of this property is then interpreted as an integer value using the grammar supported by decode and an Integer object representing this value is returned.

  The second argument is the default value. An 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 null.

  In other words, this method returns an Integer object equal to the value of:

  getInteger(nm, Integer.valueOf(val))

  but in practice it may be implemented in a manner such as:

   Integer result = getInteger(nm, null);
   return (result == null) ? Integer.valueOf(val) : result;
   

  to avoid the unnecessary allocation of an Integer object when the default value is not needed.

  Parameters:

  nm - property name.

  val - default value.

  Returns:

  the Integer value of the property.

  Throws:

  SecurityException - for the same reasons as System.getProperty

  See Also:

  • System.getProperty(java.lang.String)
  • System.getProperty(java.lang.String, java.lang.String)

• getInteger

  public static Integer getInteger(String nm, Integer val)

  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 System.getProperty(java.lang.String) method. The string value of this property is then interpreted as an integer value, as per the decode method, and an Integer object representing this value is returned; in summary:

  • If the property value begins with the two ASCII characters 0x or the ASCII character #, not followed by a minus sign, then the rest of it is parsed as a hexadecimal integer exactly as by the method valueOf(java.lang.String, int) with radix 16.
  • If the property value begins with the ASCII character 0 followed by another character, it is parsed as an octal integer exactly as by the method valueOf(java.lang.String, int) with radix 8.
  • Otherwise, the property value is parsed as a decimal integer exactly as by the method valueOf(java.lang.String, int) with radix 10.

  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 null.

  Parameters:

  nm - property name.

  val - default value.

  Returns:

  the Integer value of the property.

  Throws:

  SecurityException - for the same reasons as System.getProperty

  See Also:

  • System.getProperty(java.lang.String)
  • System.getProperty(java.lang.String, java.lang.String)

• decode

  public static Integer decode(String nm) throws NumberFormatException

  Decodes a String into an Integer. Accepts decimal, hexadecimal, and octal numbers given by the following grammar:

  DecodableString:

  Sign_opt DecimalNumeral

  Sign_opt 0x HexDigits

  Sign_opt 0X HexDigits

  Sign_opt # HexDigits

  Sign_opt 0 OctalDigits

  Sign:

  -

  +

  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.

  The sequence of characters following an optional sign and/or radix specifier ("0x", "0X", "#", or leading zero) is parsed as by the Integer.parseInt method with the indicated radix (10, 16, or 8). This sequence of characters must represent a positive value or a NumberFormatException will be thrown. The result is negated if first character of the specified String is the minus sign. No whitespace characters are permitted in the String.

  Parameters:

  nm - the String to decode.

  Returns:

  an Integer object holding the int value represented by nm

  Throws:

  NumberFormatException - if the String does not contain a parsable integer.

  See Also:

  • parseInt(java.lang.String, int)

• compareTo

  public int compareTo(Integer anotherInteger)

  Compares two Integer objects numerically.

  Specified by:

  compareTo in interface Comparable<Integer>

  Parameters:

  anotherInteger - the Integer to be compared.

  Returns:

  the value 0 if this Integer is equal to the argument Integer; a value less than 0 if this Integer is numerically less than the argument Integer; and a value greater than 0 if this Integer is numerically greater than the argument Integer (signed comparison).

  Since:

  1.2

• compare

  public static int compare(int x, int y)

  Compares two int values numerically. The value returned is identical to what would be returned by:

      Integer.valueOf(x).compareTo(Integer.valueOf(y))
   

  Parameters:

  x - the first int to compare

  y - the second int to compare

  Returns:

  the value 0 if x == y; a value less than 0 if x < y; and a value greater than 0 if x > y

  Since:

  1.7

• compareUnsigned

  public static int compareUnsigned(int x, int y)

  Compares two int values numerically treating the values as unsigned.

  Parameters:

  x - the first int to compare

  y - the second int to compare

  Returns:

  the value 0 if x == y; a value less than 0 if x < y as unsigned values; and a value greater than 0 if x > y as unsigned values

  Since:

  1.8

• toUnsignedLong

  public static long toUnsignedLong(int x)

  Converts the argument to a long by an unsigned conversion. In an unsigned conversion to a long, the high-order 32 bits of the long are zero and the low-order 32 bits are equal to the bits of the integer argument. Consequently, zero and positive int values are mapped to a numerically equal long value and negative int values are mapped to a long value equal to the input plus 2³².

  Parameters:

  x - the value to convert to an unsigned long

  Returns:

  the argument converted to long by an unsigned conversion

  Since:

  1.8

• divideUnsigned

  public static int divideUnsigned(int dividend, int divisor)

  Returns the unsigned quotient of dividing the first argument by the second where each argument and the result is interpreted as an unsigned value.

  Note that in two's complement arithmetic, the three other basic arithmetic operations of add, subtract, and multiply are bit-wise identical if the two operands are regarded as both being signed or both being unsigned. Therefore separate addUnsigned, etc. methods are not provided.

  Parameters:

  dividend - the value to be divided

  divisor - the value doing the dividing

  Returns:

  the unsigned quotient of the first argument divided by the second argument

  Since:

  1.8

  See Also:

  • remainderUnsigned(int, int)

• remainderUnsigned

  public static int remainderUnsigned(int dividend, int divisor)

  Returns the unsigned remainder from dividing the first argument by the second where each argument and the result is interpreted as an unsigned value.

  Parameters:

  dividend - the value to be divided

  divisor - the value doing the dividing

  Returns:

  the unsigned remainder of the first argument divided by the second argument

  Since:

  1.8

  See Also:

  • divideUnsigned(int, int)

• highestOneBit

  public static int highestOneBit(int i)

  Returns an int value with at most a single one-bit, in the position of the highest-order ("leftmost") one-bit in the specified 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.

  Parameters:

  i - the value whose highest one bit is to be computed

  Returns:

  an 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

• lowestOneBit

  public static int lowestOneBit(int i)

  Returns an int value with at most a single one-bit, in the position of the lowest-order ("rightmost") one-bit in the specified 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.

  Parameters:

  i - the value whose lowest one bit is to be computed

  Returns:

  an 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

• numberOfLeadingZeros

  public static int numberOfLeadingZeros(int i)

  Returns the number of zero bits preceding the highest-order ("leftmost") one-bit in the two's complement binary representation of the specified 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.

  Note that this method is closely related to the logarithm base 2. For all positive int values x:

  • floor(log₂(x)) = 31 - numberOfLeadingZeros(x)
  • ceil(log₂(x)) = 32 - numberOfLeadingZeros(x - 1)

  Parameters:

  i - the value whose number of leading zeros is to be computed

  Returns:

  the number of zero bits preceding the highest-order ("leftmost") one-bit in the two's complement binary representation of the specified int value, or 32 if the value is equal to zero.

  Since:

  1.5

• numberOfTrailingZeros

  public static int numberOfTrailingZeros(int i)

  Returns the number of zero bits following the lowest-order ("rightmost") one-bit in the two's complement binary representation of the specified 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.

  Parameters:

  i - the value whose number of trailing zeros is to be computed

  Returns:

  the number of zero bits following the lowest-order ("rightmost") one-bit in the two's complement binary representation of the specified int value, or 32 if the value is equal to zero.

  Since:

  1.5

• bitCount

  public static int bitCount(int i)

  Returns the number of one-bits in the two's complement binary representation of the specified int value. This function is sometimes referred to as the population count.

  Parameters:

  i - the value whose bits are to be counted

  Returns:

  the number of one-bits in the two's complement binary representation of the specified int value.

  Since:

  1.5

• rotateLeft

  public static int rotateLeft(int i, int distance)

  Returns the value obtained by rotating the two's complement binary representation of the specified 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.)

  Note that left rotation with a negative distance is equivalent to right rotation: 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: rotateLeft(val, distance) == rotateLeft(val, distance & 0x1F).

  Parameters:

  i - the value whose bits are to be rotated left

  distance - the number of bit positions to rotate left

  Returns:

  the value obtained by rotating the two's complement binary representation of the specified int value left by the specified number of bits.

  Since:

  1.5

• rotateRight

  public static int rotateRight(int i, int distance)

  Returns the value obtained by rotating the two's complement binary representation of the specified 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: 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: rotateRight(val, distance) == rotateRight(val, distance & 0x1F).

  Parameters:

  i - the value whose bits are to be rotated right

  distance - the number of bit positions to rotate right

  Returns:

  the value obtained by rotating the two's complement binary representation of the specified int value right by the specified number of bits.

  Since:

  1.5

• reverse

  public static int reverse(int i)

  Returns the value obtained by reversing the order of the bits in the two's complement binary representation of the specified int value.

  Parameters:

  i - the value to be reversed

  Returns:

  the value obtained by reversing order of the bits in the specified int value.

  Since:

  1.5

• compress

  public static int compress(int i, int mask)

  Returns the value obtained by compressing the bits of the specified int value, i, in accordance with the specified bit mask.

  For each one-bit value mb of the mask, from least significant to most significant, the bit value of i at the same bit location as mb is assigned to the compressed value contiguously starting from the least significant bit location. All the upper remaining bits of the compressed value are set to zero.

  API Note:

  Consider the simple case of compressing the digits of a hexadecimal value:

  Copy

  // Compressing drink to food
  compress(0xCAFEBABE, 0xFF00FFF0) == 0xCABAB
  

  Starting from the least significant hexadecimal digit at position 0 from the right, the mask 0xFF00FFF0 selects hexadecimal digits at positions 1, 2, 3, 6 and 7 of 0xCAFEBABE. The selected digits occur in the resulting compressed value contiguously from digit position 0 in the same order.

  The following identities all return true and are helpful to understand the behaviour of compress:

  Copy

  // Returns 1 if the bit at position n is one
  compress(x, 1 << n) == (x >> n & 1)
  
  // Logical shift right
  compress(x, -1 << n) == x >>> n
  
  // Any bits not covered by the mask are ignored
  compress(x, m) == compress(x & m, m)
  
  // Compressing a value by itself
  compress(m, m) == (m == -1 || m == 0) ? m : (1 << bitCount(m)) - 1
  
  // Expanding then compressing with the same mask
  compress(expand(x, m), m) == x & compress(m, m)
  

  The Sheep And Goats (SAG) operation (see Hacker's Delight, section 7.7) can be implemented as follows:

  Copy

  int compressLeft(int i, int mask) {
      // This implementation follows the description in Hacker's Delight which
      // is informative. A more optimal implementation is:
      //   Integer.compress(i, mask) << -Integer.bitCount(mask)
      return Integer.reverse(
          Integer.compress(Integer.reverse(i), Integer.reverse(mask)));
  }
  
  int sag(int i, int mask) {
      return compressLeft(i, mask) | Integer.compress(i, ~mask);
  }
  
  // Separate the sheep from the goats
  sag(0xCAFEBABE, 0xFF00FFF0) == 0xCABABFEE
  

  Parameters:

  i - the value whose bits are to be compressed

  mask - the bit mask

  Returns:

  the compressed value

  Since:

  19

  See Also:

  • expand(int, int)

• expand

  public static int expand(int i, int mask)

  Returns the value obtained by expanding the bits of the specified int value, i, in accordance with the specified bit mask.

  For each one-bit value mb of the mask, from least significant to most significant, the next contiguous bit value of i starting at the least significant bit is assigned to the expanded value at the same bit location as mb. All other remaining bits of the expanded value are set to zero.

  API Note:

  Consider the simple case of expanding the digits of a hexadecimal value:

  Copy

  expand(0x0000CABAB, 0xFF00FFF0) == 0xCA00BAB0
  

  Starting from the least significant hexadecimal digit at position 0 from the right, the mask 0xFF00FFF0 selects the first five hexadecimal digits of 0x0000CABAB. The selected digits occur in the resulting expanded value in order at positions 1, 2, 3, 6, and 7.

  The following identities all return true and are helpful to understand the behaviour of expand:

  Copy

  // Logically shift right the bit at position 0
  expand(x, 1 << n) == (x & 1) << n
  
  // Logically shift right
  expand(x, -1 << n) == x << n
  
  // Expanding all bits returns the mask
  expand(-1, m) == m
  
  // Any bits not covered by the mask are ignored
  expand(x, m) == expand(x, m) & m
  
  // Compressing then expanding with the same mask
  expand(compress(x, m), m) == x & m
  

  The select operation for determining the position of the one-bit with index n in a int value can be implemented as follows:

  Copy

  int select(int i, int n) {
      // the one-bit in i (the mask) with index n
      int nthBit = Integer.expand(1 << n, i);
      // the bit position of the one-bit with index n
      return Integer.numberOfTrailingZeros(nthBit);
  }
  
  // The one-bit with index 0 is at bit position 1
  select(0b10101010_10101010, 0) == 1
  // The one-bit with index 3 is at bit position 7
  select(0b10101010_10101010, 3) == 7
  

  Parameters:

  i - the value whose bits are to be expanded

  mask - the bit mask

  Returns:

  the expanded value

  Since:

  19

  See Also:

  • compress(int, int)

• signum

  public static int signum(int i)

  Returns the signum function of the specified 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.)

  Parameters:

  i - the value whose signum is to be computed

  Returns:

  the signum function of the specified int value.

  Since:

  1.5

• reverseBytes

  public static int reverseBytes(int i)

  Returns the value obtained by reversing the order of the bytes in the two's complement representation of the specified int value.

  Parameters:

  i - the value whose bytes are to be reversed

  Returns:

  the value obtained by reversing the bytes in the specified int value.

  Since:

  1.5

• sum

  public static int sum(int a, int b)

  Adds two integers together as per the + operator.

  Parameters:

  a - the first operand

  b - the second operand

  Returns:

  the sum of a and b

  Since:

  1.8

  See Also:

  • BinaryOperator

• max

  public static int max(int a, int b)

  Returns the greater of two int values as if by calling Math.max.

  Parameters:

  a - the first operand

  b - the second operand

  Returns:

  the greater of a and b

  Since:

  1.8

  See Also:

  • BinaryOperator

• min

  public static int min(int a, int b)

  Returns the smaller of two int values as if by calling Math.min.

  Parameters:

  a - the first operand

  b - the second operand

  Returns:

  the smaller of a and b

  Since:

  1.8

  See Also:

  • BinaryOperator

• describeConstable

  public Optional<Integer> describeConstable()

  Returns an Optional containing the nominal descriptor for this instance, which is the instance itself.

  Specified by:

  describeConstable in interface Constable

  Returns:

  an Optional describing the Integer instance

  Since:

  12

• resolveConstantDesc

  public Integer resolveConstantDesc(MethodHandles.Lookup lookup)

  Resolves this instance as a ConstantDesc, the result of which is the instance itself.

  Specified by:

  resolveConstantDesc in interface ConstantDesc

  Parameters:

  lookup - ignored

  Returns:

  the Integer instance

  Since:

  12