- All Implemented Interfaces:
Serializable,Comparable<Long>,Constable,ConstantDesc
Long class wraps a value of the primitive type
long in an object. An object of type Long contains a
single field whose type is long.
In addition, this class provides several methods for converting
a long to a String and a String to a
long, as well as other constants and methods useful when dealing
with a long.
This is a value-based class; programmers should treat instances that are equal as interchangeable and should not use instances for synchronization, or unpredictable behavior may occur. For example, in a future release, synchronization may fail.
Implementation note: The implementations of the "bit twiddling"
methods (such as highestOneBit and
numberOfTrailingZeros) are
based on material from Henry S. Warren, Jr.'s Hacker's
Delight, (Addison Wesley, 2002).
- Since:
- 1.0
- See Also:
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final intThe number of bytes used to represent alongvalue in two's complement binary form.static final longA constant holding the maximum value alongcan have, 263-1.static final longA constant holding the minimum value alongcan have, -263.static final intThe number of bits used to represent alongvalue in two's complement binary form.TheClassinstance representing the primitive typelong. -
Constructor Summary
ConstructorsConstructorDescriptionLong(long value) Deprecated, for removal: This API element is subject to removal in a future version.It is rarely appropriate to use this constructor.Deprecated, for removal: This API element is subject to removal in a future version.It is rarely appropriate to use this constructor. -
Method Summary
Modifier and TypeMethodDescriptionstatic intbitCount(long i) Returns the number of one-bits in the two's complement binary representation of the specifiedlongvalue.byteReturns the value of thisLongas abyteafter a narrowing primitive conversion.static intcompare(long x, long y) Compares twolongvalues numerically.intCompares twoLongobjects numerically.static intcompareUnsigned(long x, long y) Compares twolongvalues numerically treating the values as unsigned.static longcompress(long i, long mask) Returns the value obtained by compressing the bits of the specifiedlongvalue,i, in accordance with the specified bit mask.static LongDecodes aStringinto aLong.Returns anOptionalcontaining the nominal descriptor for this instance, which is the instance itself.static longdivideUnsigned(long dividend, long 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.doubleReturns the value of thisLongas adoubleafter a widening primitive conversion.booleanCompares this object to the specified object.static longexpand(long i, long mask) Returns the value obtained by expanding the bits of the specifiedlongvalue,i, in accordance with the specified bit mask.floatReturns the value of thisLongas afloatafter a widening primitive conversion.static LongDetermines thelongvalue of the system property with the specified name.static LongDetermines thelongvalue of the system property with the specified name.static LongReturns thelongvalue of the system property with the specified name.inthashCode()Returns a hash code for thisLong.static inthashCode(long value) Returns a hash code for alongvalue; compatible withLong.hashCode().static longhighestOneBit(long i) Returns alongvalue with at most a single one-bit, in the position of the highest-order ("leftmost") one-bit in the specifiedlongvalue.intintValue()Returns the value of thisLongas anintafter a narrowing primitive conversion.longReturns the value of thisLongas alongvalue.static longlowestOneBit(long i) Returns alongvalue with at most a single one-bit, in the position of the lowest-order ("rightmost") one-bit in the specifiedlongvalue.static longmax(long a, long b) Returns the greater of twolongvalues as if by callingMath.max.static longmin(long a, long b) Returns the smaller of twolongvalues as if by callingMath.min.static intnumberOfLeadingZeros(long i) Returns the number of zero bits preceding the highest-order ("leftmost") one-bit in the two's complement binary representation of the specifiedlongvalue.static intnumberOfTrailingZeros(long i) Returns the number of zero bits following the lowest-order ("rightmost") one-bit in the two's complement binary representation of the specifiedlongvalue.static longparseLong(CharSequence s, int beginIndex, int endIndex, int radix) Parses theCharSequenceargument as a signedlongin the specifiedradix, beginning at the specifiedbeginIndexand extending toendIndex - 1.static longParses the string argument as a signed decimallong.static longParses the string argument as a signedlongin the radix specified by the second argument.static longparseUnsignedLong(CharSequence s, int beginIndex, int endIndex, int radix) Parses theCharSequenceargument as an unsignedlongin the specifiedradix, beginning at the specifiedbeginIndexand extending toendIndex - 1.static longParses the string argument as an unsigned decimallong.static longparseUnsignedLong(String s, int radix) Parses the string argument as an unsignedlongin the radix specified by the second argument.static longremainderUnsigned(long dividend, long 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.Resolves this instance as aConstantDesc, the result of which is the instance itself.static longreverse(long i) Returns the value obtained by reversing the order of the bits in the two's complement binary representation of the specifiedlongvalue.static longreverseBytes(long i) Returns the value obtained by reversing the order of the bytes in the two's complement representation of the specifiedlongvalue.static longrotateLeft(long i, int distance) Returns the value obtained by rotating the two's complement binary representation of the specifiedlongvalue left by the specified number of bits.static longrotateRight(long i, int distance) Returns the value obtained by rotating the two's complement binary representation of the specifiedlongvalue right by the specified number of bits.shortReturns the value of thisLongas ashortafter a narrowing primitive conversion.static intsignum(long i) Returns the signum function of the specifiedlongvalue.static longsum(long a, long b) Adds twolongvalues together as per the + operator.static StringtoBinaryString(long i) Returns a string representation of thelongargument as an unsigned integer in base 2.static StringtoHexString(long i) Returns a string representation of thelongargument as an unsigned integer in base 16.static StringtoOctalString(long i) Returns a string representation of thelongargument as an unsigned integer in base 8.toString()Returns aStringobject representing thisLong's value.static StringtoString(long i) Returns aStringobject representing the specifiedlong.static StringtoString(long i, int radix) Returns a string representation of the first argument in the radix specified by the second argument.static StringtoUnsignedString(long i) Returns a string representation of the argument as an unsigned decimal value.static StringtoUnsignedString(long i, int radix) Returns a string representation of the first argument as an unsigned integer value in the radix specified by the second argument.static LongvalueOf(long l) Returns aLonginstance representing the specifiedlongvalue.static LongReturns aLongobject holding the value of the specifiedString.static LongReturns aLongobject holding the value extracted from the specifiedStringwhen parsed with the radix given by the second argument.
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Field Details
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MIN_VALUE
A constant holding the minimum value alongcan have, -263.- See Also:
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MAX_VALUE
A constant holding the maximum value alongcan have, 263-1.- See Also:
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TYPE
TheClassinstance representing the primitive typelong.- Since:
- 1.1
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SIZE
The number of bits used to represent alongvalue in two's complement binary form.- Since:
- 1.5
- See Also:
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BYTES
public static final int BYTESThe number of bytes used to represent alongvalue in two's complement binary form.- Since:
- 1.8
- See Also:
-
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Constructor Details
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Long
Deprecated, for removal: This API element is subject to removal in a future version.It is rarely appropriate to use this constructor. The static factoryvalueOf(long)is generally a better choice, as it is likely to yield significantly better space and time performance.Constructs a newly allocatedLongobject that represents the specifiedlongargument.- Parameters:
value- the value to be represented by theLongobject.
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Long
Deprecated, for removal: This API element is subject to removal in a future version.It is rarely appropriate to use this constructor. UseparseLong(String)to convert a string to alongprimitive, or usevalueOf(String)to convert a string to aLongobject.Constructs a newly allocatedLongobject that represents thelongvalue indicated by theStringparameter. The string is converted to alongvalue in exactly the manner used by theparseLongmethod for radix 10.- Parameters:
s- theStringto be converted to aLong.- Throws:
NumberFormatException- if theStringdoes not contain a parsablelong.
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Method Details
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toString
Returns a string representation of the first argument in the radix specified by the second argument.If the radix is smaller than
Character.MIN_RADIXor larger thanCharacter.MAX_RADIX, then the radix10is used instead.If the first argument is negative, the first element of the result is the ASCII minus sign
'-'('\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:
These are0123456789abcdefghijklmnopqrstuvwxyz'\u0030'through'\u0039'and'\u0061'through'\u007a'. Ifradixis 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) are0123456789abcdef. If uppercase letters are desired, theString.toUpperCase()method may be called on the result:Long.toString(n, 16).toUpperCase()- Parameters:
i- alongto 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:
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toUnsignedString
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_RADIXor larger thanCharacter.MAX_RADIX, then the radix10is 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:
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toHexString
Returns a string representation of thelongargument as an unsigned integer in base 16.The unsigned
longvalue is the argument plus 264 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 leading0s.The value of the argument can be recovered from the returned string
sby callingLong.parseUnsignedLong(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:
These are the characters0123456789abcdef'\u0030'through'\u0039'and'\u0061'through'\u0066'. If uppercase letters are desired, theString.toUpperCase()method may be called on the result:Long.toHexString(n).toUpperCase()- API Note:
- The
HexFormatclass provides formatting and parsing of byte arrays and primitives to return a string or adding to anAppendable.HexFormatformats 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- alongto be converted to a string.- Returns:
- the string representation of the unsigned
longvalue represented by the argument in hexadecimal (base 16). - Since:
- 1.0.2
- See Also:
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toOctalString
Returns a string representation of thelongargument as an unsigned integer in base 8.The unsigned
longvalue is the argument plus 264 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 leading0s.The value of the argument can be recovered from the returned string
sby callingLong.parseUnsignedLong(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:
These are the characters01234567'\u0030'through'\u0037'.- Parameters:
i- alongto be converted to a string.- Returns:
- the string representation of the unsigned
longvalue represented by the argument in octal (base 8). - Since:
- 1.0.2
- See Also:
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toBinaryString
Returns a string representation of thelongargument as an unsigned integer in base 2.The unsigned
longvalue is the argument plus 264 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 leading0s.The value of the argument can be recovered from the returned string
sby callingLong.parseUnsignedLong(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- alongto be converted to a string.- Returns:
- the string representation of the unsigned
longvalue represented by the argument in binary (base 2). - Since:
- 1.0.2
- See Also:
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toString
Returns aStringobject representing the specifiedlong. The argument is converted to signed decimal representation and returned as a string, exactly as if the argument and the radix 10 were given as arguments to thetoString(long, int)method.- Parameters:
i- alongto be converted.- Returns:
- a string representation of the argument in base 10.
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toUnsignedString
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 thetoUnsignedString(long, 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:
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parseLong
Parses the string argument as a signedlongin the radix specified by the second argument. The characters in the string must all be digits of the specified radix (as determined by whetherCharacter.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 resultinglongvalue is returned.Note that neither the character
L('\u004C') norl('\u006C') is permitted to appear at the end of the string as a type indicator, as would be permitted in Java programming language source code - except that eitherLorlmay appear as a digit for a radix greater than or equal to 22.An exception of type
NumberFormatExceptionis thrown if any of the following situations occurs:- The first argument is
nullor is a string of length zero. - The
radixis either smaller thanCharacter.MIN_RADIXor larger thanCharacter.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
long.
Examples:
parseLong("0", 10) returns 0L parseLong("473", 10) returns 473L parseLong("+42", 10) returns 42L parseLong("-0", 10) returns 0L parseLong("-FF", 16) returns -255L parseLong("1100110", 2) returns 102L parseLong("99", 8) throws a NumberFormatException parseLong("Hazelnut", 10) throws a NumberFormatException parseLong("Hazelnut", 36) returns 1356099454469L- Parameters:
s- theStringcontaining thelongrepresentation to be parsed.radix- the radix to be used while parsings.- Returns:
- the
longrepresented by the string argument in the specified radix. - Throws:
NumberFormatException- if the string does not contain a parsablelong.
- The first argument is
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parseLong
public static long parseLong(CharSequence s, int beginIndex, int endIndex, int radix) throws NumberFormatException Parses theCharSequenceargument as a signedlongin the specifiedradix, beginning at the specifiedbeginIndexand extending toendIndex - 1.The method does not take steps to guard against the
CharSequencebeing mutated while parsing.- Parameters:
s- theCharSequencecontaining thelongrepresentation to be parsedbeginIndex- the beginning index, inclusive.endIndex- the ending index, exclusive.radix- the radix to be used while parsings.- Returns:
- the signed
longrepresented by the subsequence in the specified radix. - Throws:
NullPointerException- ifsis null.IndexOutOfBoundsException- ifbeginIndexis negative, or ifbeginIndexis greater thanendIndexor ifendIndexis greater thans.length().NumberFormatException- if theCharSequencedoes not contain a parsablelongin the specifiedradix, or ifradixis either smaller thanCharacter.MIN_RADIXor larger thanCharacter.MAX_RADIX.- Since:
- 9
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parseLong
Parses the string argument as a signed decimallong. 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 resultinglongvalue is returned, exactly as if the argument and the radix10were given as arguments to theparseLong(java.lang.String, int)method.Note that neither the character
L('\u004C') norl('\u006C') is permitted to appear at the end of the string as a type indicator, as would be permitted in Java programming language source code.- Parameters:
s- aStringcontaining thelongrepresentation to be parsed- Returns:
- the
longrepresented by the argument in decimal. - Throws:
NumberFormatException- if the string does not contain a parsablelong.
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parseUnsignedLong
Parses the string argument as an unsignedlongin the radix specified by the second argument. An unsigned integer maps the values usually associated with negative numbers to positive numbers larger thanMAX_VALUE. The characters in the string must all be digits of the specified radix (as determined by whetherCharacter.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
NumberFormatExceptionis thrown if any of the following situations occurs:- The first argument is
nullor is a string of length zero. - The radix is either smaller than
Character.MIN_RADIXor larger thanCharacter.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
long, 264-1.
- Parameters:
s- theStringcontaining the unsigned integer representation to be parsedradix- the radix to be used while parsings.- Returns:
- the unsigned
longrepresented by the string argument in the specified radix. - Throws:
NumberFormatException- if theStringdoes not contain a parsablelong.- Since:
- 1.8
- The first argument is
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parseUnsignedLong
public static long parseUnsignedLong(CharSequence s, int beginIndex, int endIndex, int radix) throws NumberFormatException Parses theCharSequenceargument as an unsignedlongin the specifiedradix, beginning at the specifiedbeginIndexand extending toendIndex - 1.The method does not take steps to guard against the
CharSequencebeing mutated while parsing.- Parameters:
s- theCharSequencecontaining the unsignedlongrepresentation to be parsedbeginIndex- the beginning index, inclusive.endIndex- the ending index, exclusive.radix- the radix to be used while parsings.- Returns:
- the unsigned
longrepresented by the subsequence in the specified radix. - Throws:
NullPointerException- ifsis null.IndexOutOfBoundsException- ifbeginIndexis negative, or ifbeginIndexis greater thanendIndexor ifendIndexis greater thans.length().NumberFormatException- if theCharSequencedoes not contain a parsable unsignedlongin the specifiedradix, or ifradixis either smaller thanCharacter.MIN_RADIXor larger thanCharacter.MAX_RADIX.- Since:
- 9
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parseUnsignedLong
Parses the string argument as an unsigned decimallong. 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 theparseUnsignedLong(java.lang.String, int)method.- Parameters:
s- aStringcontaining the unsignedlongrepresentation to be parsed- Returns:
- the unsigned
longvalue represented by the decimal string argument - Throws:
NumberFormatException- if the string does not contain a parsable unsigned integer.- Since:
- 1.8
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valueOf
Returns aLongobject holding the value extracted from the specifiedStringwhen parsed with the radix given by the second argument. The first argument is interpreted as representing a signedlongin the radix specified by the second argument, exactly as if the arguments were given to theparseLong(java.lang.String, int)method. The result is aLongobject that represents thelongvalue specified by the string.In other words, this method returns a
Longobject equal to the value of:Long.valueOf(Long.parseLong(s, radix))- Parameters:
s- the string to be parsedradix- the radix to be used in interpretings- Returns:
- a
Longobject holding the value represented by the string argument in the specified radix. - Throws:
NumberFormatException- If theStringdoes not contain a parsablelong.
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valueOf
Returns aLongobject holding the value of the specifiedString. The argument is interpreted as representing a signed decimallong, exactly as if the argument were given to theparseLong(java.lang.String)method. The result is aLongobject that represents the integer value specified by the string.In other words, this method returns a
Longobject equal to the value of:Long.valueOf(Long.parseLong(s))- Parameters:
s- the string to be parsed.- Returns:
- a
Longobject holding the value represented by the string argument. - Throws:
NumberFormatException- If the string cannot be parsed as along.
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valueOf
Returns aLonginstance representing the specifiedlongvalue. If a newLonginstance is not required, this method should generally be used in preference to the constructorLong(long), 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:
l- a long value.- Returns:
- a
Longinstance representingl. - Since:
- 1.5
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decode
Decodes aStringinto aLong. Accepts decimal, hexadecimal, and octal numbers given by the following grammar:
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.- DecodableString:
- Signopt DecimalNumeral
- Signopt
0xHexDigits- Signopt
0XHexDigits- Signopt
#HexDigits- Signopt
0OctalDigits - Signopt
- Sign:
-+
The sequence of characters following an optional sign and/or radix specifier ("
0x", "0X", "#", or leading zero) is parsed as by theLong.parseLongmethod with the indicated radix (10, 16, or 8). This sequence of characters must represent a positive value or aNumberFormatExceptionwill be thrown. The result is negated if first character of the specifiedStringis the minus sign. No whitespace characters are permitted in theString.- Parameters:
nm- theStringto decode.- Returns:
- a
Longobject holding thelongvalue represented bynm - Throws:
NumberFormatException- if theStringdoes not contain a parsablelong.- Since:
- 1.2
- See Also:
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byteValue
public byte byteValue()Returns the value of thisLongas abyteafter a narrowing primitive conversion.- Overrides:
byteValuein classNumber- Returns:
- the numeric value represented by this object after conversion
to type
byte. - See Java Language Specification:
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5.1.3 Narrowing Primitive Conversion
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shortValue
public short shortValue()Returns the value of thisLongas ashortafter a narrowing primitive conversion.- Overrides:
shortValuein classNumber- Returns:
- the numeric value represented by this object after conversion
to type
short. - See Java Language Specification:
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5.1.3 Narrowing Primitive Conversion
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intValue
public int intValue()Returns the value of thisLongas anintafter a narrowing primitive conversion.- Specified by:
intValuein classNumber- Returns:
- the numeric value represented by this object after conversion
to type
int. - See Java Language Specification:
-
5.1.3 Narrowing Primitive Conversion
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longValue
public long longValue()Returns the value of thisLongas alongvalue. -
floatValue
public float floatValue()Returns the value of thisLongas afloatafter a widening primitive conversion.- Specified by:
floatValuein classNumber- Returns:
- the numeric value represented by this object after conversion
to type
float. - See Java Language Specification:
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5.1.2 Widening Primitive Conversion
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doubleValue
public double doubleValue()Returns the value of thisLongas adoubleafter a widening primitive conversion.- Specified by:
doubleValuein classNumber- Returns:
- the numeric value represented by this object after conversion
to type
double. - See Java Language Specification:
-
5.1.2 Widening Primitive Conversion
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toString
Returns aStringobject representing thisLong's value. The value is converted to signed decimal representation and returned as a string, exactly as if thelongvalue were given as an argument to thetoString(long)method. -
hashCode
public int hashCode()Returns a hash code for thisLong. The result is the exclusive OR of the two halves of the primitivelongvalue held by thisLongobject. That is, the hashcode is the value of the expression:(int)(this.longValue()^(this.longValue()>>>32)) -
hashCode
public static int hashCode(long value) Returns a hash code for alongvalue; compatible withLong.hashCode().- Parameters:
value- the value to hash- Returns:
- a hash code value for a
longvalue. - Since:
- 1.8
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equals
Compares this object to the specified object. The result istrueif and only if the argument is notnulland is aLongobject that contains the samelongvalue as this object. -
getLong
Determines thelongvalue 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 alongvalue using the grammar supported bydecodeand aLongobject 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, thennullis returned.In other words, this method returns a
Longobject equal to the value of:getLong(nm, null)- Parameters:
nm- property name.- Returns:
- the
Longvalue of the property. - Throws:
SecurityException- for the same reasons asSystem.getProperty- See Also:
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getLong
Determines thelongvalue 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 alongvalue using the grammar supported bydecodeand aLongobject representing this value is returned.The second argument is the default value. A
Longobject 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 a
Longobject equal to the value of:
but in practice it may be implemented in a manner such as:getLong(nm, Long.valueOf(val))
to avoid the unnecessary allocation of aLong result = getLong(nm, null); return (result == null) ? Long.valueOf(val) : result;
Longobject when the default value is not needed.- Parameters:
nm- property name.val- default value.- Returns:
- the
Longvalue of the property. - Throws:
SecurityException- for the same reasons asSystem.getProperty- See Also:
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getLong
Returns thelongvalue 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 theSystem.getProperty(java.lang.String)method. The string value of this property is then interpreted as alongvalue, as per thedecodemethod, and aLongobject representing this value is returned; in summary:- If the property value begins with the two ASCII characters
0xor the ASCII character#, not followed by a minus sign, then the rest of it is parsed as a hexadecimal integer exactly as for the methodvalueOf(java.lang.String, int)with radix 16. - If the property value begins with the ASCII character
0followed by another character, it is parsed as an octal integer exactly as by the methodvalueOf(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.
Note that, in every case, neither
L('\u004C') norl('\u006C') is permitted to appear at the end of the property value as a type indicator, as would be permitted in Java programming language source code.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
Longvalue of the property. - Throws:
SecurityException- for the same reasons asSystem.getProperty- See Also:
- If the property value begins with the two ASCII characters
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compareTo
Compares twoLongobjects numerically.- Specified by:
compareToin interfaceComparable<Long>- Parameters:
anotherLong- theLongto be compared.- Returns:
- the value
0if thisLongis equal to the argumentLong; a value less than0if thisLongis numerically less than the argumentLong; and a value greater than0if thisLongis numerically greater than the argumentLong(signed comparison). - Since:
- 1.2
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compare
public static int compare(long x, long y) Compares twolongvalues numerically. The value returned is identical to what would be returned by:Long.valueOf(x).compareTo(Long.valueOf(y))- Parameters:
x- the firstlongto comparey- the secondlongto compare- Returns:
- the value
0ifx == y; a value less than0ifx < y; and a value greater than0ifx > y - Since:
- 1.7
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compareUnsigned
public static int compareUnsigned(long x, long y) Compares twolongvalues numerically treating the values as unsigned.- Parameters:
x- the firstlongto comparey- the secondlongto compare- Returns:
- the value
0ifx == y; a value less than0ifx < yas unsigned values; and a value greater than0ifx > yas unsigned values - Since:
- 1.8
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divideUnsigned
public static long divideUnsigned(long dividend, long 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 divideddivisor- the value doing the dividing- Returns:
- the unsigned quotient of the first argument divided by the second argument
- Since:
- 1.8
- See Also:
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remainderUnsigned
public static long remainderUnsigned(long dividend, long 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 divideddivisor- the value doing the dividing- Returns:
- the unsigned remainder of the first argument divided by the second argument
- Since:
- 1.8
- See Also:
-
highestOneBit
public static long highestOneBit(long i) Returns alongvalue with at most a single one-bit, in the position of the highest-order ("leftmost") one-bit in the specifiedlongvalue. 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:
- a
longvalue 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 long lowestOneBit(long i) Returns alongvalue with at most a single one-bit, in the position of the lowest-order ("rightmost") one-bit in the specifiedlongvalue. 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:
- a
longvalue 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(long i) Returns the number of zero bits preceding the highest-order ("leftmost") one-bit in the two's complement binary representation of the specifiedlongvalue. Returns 64 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
longvalues x:- floor(log2(x)) =
63 - numberOfLeadingZeros(x) - ceil(log2(x)) =
64 - 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
longvalue, or 64 if the value is equal to zero. - Since:
- 1.5
- floor(log2(x)) =
-
numberOfTrailingZeros
public static int numberOfTrailingZeros(long i) Returns the number of zero bits following the lowest-order ("rightmost") one-bit in the two's complement binary representation of the specifiedlongvalue. Returns 64 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
longvalue, or 64 if the value is equal to zero. - Since:
- 1.5
-
bitCount
public static int bitCount(long i) Returns the number of one-bits in the two's complement binary representation of the specifiedlongvalue. 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
longvalue. - Since:
- 1.5
-
rotateLeft
public static long rotateLeft(long i, int distance) Returns the value obtained by rotating the two's complement binary representation of the specifiedlongvalue 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 64 is a no-op, so all but the last six bits of the rotation distance can be ignored, even if the distance is negative:rotateLeft(val, distance) == rotateLeft(val, distance & 0x3F).- Parameters:
i- the value whose bits are to be rotated leftdistance- the number of bit positions to rotate left- Returns:
- the value obtained by rotating the two's complement binary
representation of the specified
longvalue left by the specified number of bits. - Since:
- 1.5
-
rotateRight
public static long rotateRight(long i, int distance) Returns the value obtained by rotating the two's complement binary representation of the specifiedlongvalue 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 64 is a no-op, so all but the last six bits of the rotation distance can be ignored, even if the distance is negative:rotateRight(val, distance) == rotateRight(val, distance & 0x3F).- Parameters:
i- the value whose bits are to be rotated rightdistance- the number of bit positions to rotate right- Returns:
- the value obtained by rotating the two's complement binary
representation of the specified
longvalue right by the specified number of bits. - Since:
- 1.5
-
reverse
public static long reverse(long i) Returns the value obtained by reversing the order of the bits in the two's complement binary representation of the specifiedlongvalue.- Parameters:
i- the value to be reversed- Returns:
- the value obtained by reversing order of the bits in the
specified
longvalue. - Since:
- 1.5
-
compress
public static long compress(long i, long mask) Returns the value obtained by compressing the bits of the specifiedlongvalue,i, in accordance with the specified bit mask.For each one-bit value
mbof the mask, from least significant to most significant, the bit value ofiat the same bit location asmbis 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:
Starting from the least significant hexadecimal digit at position 0 from the right, the mask
// Compressing drink to food compress(0xCAFEBABEL, 0xFF00FFF0L) == 0xCABABL0xFF00FFF0selects hexadecimal digits at positions 1, 2, 3, 6 and 7 of0xCAFEBABE. The selected digits occur in the resulting compressed value contiguously from digit position 0 in the same order.The following identities all return
trueand are helpful to understand the behaviour ofcompress:// Returns 1 if the bit at position n is one compress(x, 1L << n) == (x >> n & 1) // Logical shift right compress(x, -1L << 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 : (1L << 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:
long compressLeft(long i, long mask) { // This implementation follows the description in Hacker's Delight which // is informative. A more optimal implementation is: // Long.compress(i, mask) << -Long.bitCount(mask) return Long.reverse( Long.compress(Long.reverse(i), Long.reverse(mask))); } long sag(long i, long mask) { return compressLeft(i, mask) | Long.compress(i, ~mask); } // Separate the sheep from the goats sag(0x00000000_CAFEBABEL, 0xFFFFFFFF_FF00FFF0L) == 0x00000000_CABABFEEL - Parameters:
i- the value whose bits are to be compressedmask- the bit mask- Returns:
- the compressed value
- Since:
- 19
- See Also:
-
expand
public static long expand(long i, long mask) Returns the value obtained by expanding the bits of the specifiedlongvalue,i, in accordance with the specified bit mask.For each one-bit value
mbof the mask, from least significant to most significant, the next contiguous bit value ofistarting at the least significant bit is assigned to the expanded value at the same bit location asmb. 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:
Starting from the least significant hexadecimal digit at position 0 from the right, the mask
expand(0x0000CABABL, 0xFF00FFF0L) == 0xCA00BAB0L0xFF00FFF0selects the first five hexadecimal digits of0x0000CABAB. The selected digits occur in the resulting expanded value in order at positions 1, 2, 3, 6, and 7.The following identities all return
trueand are helpful to understand the behaviour ofexpand:// Logically shift right the bit at position 0 expand(x, 1L << n) == (x & 1) << n // Logically shift right expand(x, -1L << n) == x << n // Expanding all bits returns the mask expand(-1L, 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 & mThe select operation for determining the position of the one-bit with index
nin alongvalue can be implemented as follows:long select(long i, long n) { // the one-bit in i (the mask) with index n long nthBit = Long.expand(1L << n, i); // the bit position of the one-bit with index n return Long.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 expandedmask- the bit mask- Returns:
- the expanded value
- Since:
- 19
- See Also:
-
signum
public static int signum(long i) Returns the signum function of the specifiedlongvalue. (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
longvalue. - Since:
- 1.5
-
reverseBytes
public static long reverseBytes(long i) Returns the value obtained by reversing the order of the bytes in the two's complement representation of the specifiedlongvalue.- Parameters:
i- the value whose bytes are to be reversed- Returns:
- the value obtained by reversing the bytes in the specified
longvalue. - Since:
- 1.5
-
sum
public static long sum(long a, long b) Adds twolongvalues together as per the + operator.- Parameters:
a- the first operandb- the second operand- Returns:
- the sum of
aandb - Since:
- 1.8
- See Also:
-
max
public static long max(long a, long b) Returns the greater of twolongvalues as if by callingMath.max.- Parameters:
a- the first operandb- the second operand- Returns:
- the greater of
aandb - Since:
- 1.8
- See Also:
-
min
public static long min(long a, long b) Returns the smaller of twolongvalues as if by callingMath.min.- Parameters:
a- the first operandb- the second operand- Returns:
- the smaller of
aandb - Since:
- 1.8
- See Also:
-
describeConstable
Returns anOptionalcontaining the nominal descriptor for this instance, which is the instance itself.- Specified by:
describeConstablein interfaceConstable- Returns:
- an
Optionaldescribing the Long instance - Since:
- 12
-
resolveConstantDesc
Resolves this instance as aConstantDesc, the result of which is the instance itself.- Specified by:
resolveConstantDescin interfaceConstantDesc- Parameters:
lookup- ignored- Returns:
- the Long instance
- Since:
- 12
-