Module java.base

Package java.lang

Class Long

java.lang.Object

java.lang.Number

java.lang.Long

All Implemented Interfaces:

Serializable, Comparable<Long>, Constable, ConstantDesc

public final class Long
extends Number
implements Comparable<Long>, Constable, ConstantDesc

The 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:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static final int	BYTES	The number of bytes used to represent a long value in two's complement binary form.
static final long	MAX_VALUE	A constant holding the maximum value a long can have, 263-1.
static final long	MIN_VALUE	A constant holding the minimum value a long can have, -263.
static final int	SIZE	The number of bits used to represent a long value in two's complement binary form.
static final Class<Long>	TYPE	The Class instance representing the primitive type long.

Constructor Summary

Constructors

Constructor	Description
Long(long value)	Deprecated, for removal: This API element is subject to removal in a future version. It is rarely appropriate to use this constructor.
Long(String s)	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 Type	Method	Description
static int	bitCount(long i)	Returns the number of one-bits in the two's complement binary representation of the specified long value.
byte	byteValue()	Returns the value of this Long as a byte after a narrowing primitive conversion.
static int	compare(long x, long y)	Compares two long values numerically.
int	compareTo(Long anotherLong)	Compares two Long objects numerically.
static int	compareUnsigned(long x, long y)	Compares two long values numerically treating the values as unsigned.
static long	compress(long i, long mask)	Returns the value obtained by compressing the bits of the specified long value, i, in accordance with the specified bit mask.
static Long	decode(String nm)	Decodes a String into a Long.
Optional<Long>	describeConstable()	Returns an Optional containing the nominal descriptor for this instance, which is the instance itself.
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.
double	doubleValue()	Returns the value of this Long as a double after a widening primitive conversion.
boolean	equals(Object obj)	Compares this object to the specified object.
static long	expand(long i, long mask)	Returns the value obtained by expanding the bits of the specified long value, i, in accordance with the specified bit mask.
float	floatValue()	Returns the value of this Long as a float after a widening primitive conversion.
static Long	getLong(String nm)	Determines the long value of the system property with the specified name.
static Long	getLong(String nm, long val)	Determines the long value of the system property with the specified name.
static Long	getLong(String nm, Long val)	Returns the long value of the system property with the specified name.
int	hashCode()	Returns a hash code for this Long.
static int	hashCode(long value)	Returns a hash code for a long value; compatible with Long.hashCode().
static long	highestOneBit(long i)	Returns a long value with at most a single one-bit, in the position of the highest-order ("leftmost") one-bit in the specified long value.
int	intValue()	Returns the value of this Long as an int after a narrowing primitive conversion.
long	longValue()	Returns the value of this Long as a long value.
static long	lowestOneBit(long i)	Returns a long value with at most a single one-bit, in the position of the lowest-order ("rightmost") one-bit in the specified long value.
static long	max(long a, long b)	Returns the greater of two long values as if by calling Math.max.
static long	min(long a, long b)	Returns the smaller of two long values as if by calling Math.min.
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 specified long value.
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 specified long value.
static long	parseLong(CharSequence s, int beginIndex, int endIndex, int radix)	Parses the CharSequence argument as a signed long in the specified radix, beginning at the specified beginIndex and extending to endIndex - 1.
static long	parseLong(String s)	Parses the string argument as a signed decimal long.
static long	parseLong(String s, int radix)	Parses the string argument as a signed long in the radix specified by the second argument.
static long	parseUnsignedLong(CharSequence s, int beginIndex, int endIndex, int radix)	Parses the CharSequence argument as an unsigned long in the specified radix, beginning at the specified beginIndex and extending to endIndex - 1.
static long	parseUnsignedLong(String s)	Parses the string argument as an unsigned decimal long.
static long	parseUnsignedLong(String s, int radix)	Parses the string argument as an unsigned long in the radix specified by the second argument.
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.
Long	resolveConstantDesc(MethodHandles.Lookup lookup)	Resolves this instance as a ConstantDesc, the result of which is the instance itself.
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 specified long value.
static long	reverseBytes(long i)	Returns the value obtained by reversing the order of the bytes in the two's complement representation of the specified long value.
static long	rotateLeft(long i, int distance)	Returns the value obtained by rotating the two's complement binary representation of the specified long value left by the specified number of bits.
static long	rotateRight(long i, int distance)	Returns the value obtained by rotating the two's complement binary representation of the specified long value right by the specified number of bits.
short	shortValue()	Returns the value of this Long as a short after a narrowing primitive conversion.
static int	signum(long i)	Returns the signum function of the specified long value.
static long	sum(long a, long b)	Adds two long values together as per the + operator.
static String	toBinaryString(long i)	Returns a string representation of the long argument as an unsigned integer in base 2.
static String	toHexString(long i)	Returns a string representation of the long argument as an unsigned integer in base 16.
static String	toOctalString(long i)	Returns a string representation of the long argument as an unsigned integer in base 8.
String	toString()	Returns a String object representing this Long's value.
static String	toString(long i)	Returns a String object representing the specified long.
static String	toString(long i, int radix)	Returns a string representation of the first argument in the radix specified by the second argument.
static String	toUnsignedString(long i)	Returns a string representation of the argument as an unsigned decimal value.
static String	toUnsignedString(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 Long	valueOf(long l)	Returns a Long instance representing the specified long value.
static Long	valueOf(String s)	Returns a Long object holding the value of the specified String.
static Long	valueOf(String s, int radix)	Returns a Long object holding the value extracted from the specified String when parsed with the radix given by the second argument.

Methods declared in class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Details

MIN_VALUE

@Native
public static final long MIN_VALUE

A constant holding the minimum value a long can have, -2⁶³.

See Also:

• Constant Field Values

MAX_VALUE

@Native
public static final long MAX_VALUE

A constant holding the maximum value a long can have, 2⁶³-1.

See Also:

• Constant Field Values

TYPE

public static final Class<Long> TYPE

The Class instance representing the primitive type long.

Since:

1.1

SIZE

@Native
public static final int SIZE

The number of bits used to represent a long value in two's complement binary form.

Since:

1.5

See Also:

• Constant Field Values

BYTES

public static final int BYTES

The number of bytes used to represent a long value in two's complement binary form.

Since:

1.8

See Also:

• Constant Field Values

Constructor Details

Long

@Deprecated(since="9",
            forRemoval=true)
public Long(long value)

Deprecated, for removal: This API element is subject to removal in a future version.

It is rarely appropriate to use this constructor. The static factory valueOf(long) is generally a better choice, as it is likely to yield significantly better space and time performance.

Constructs a newly allocated Long object that represents the specified long argument.

Parameters:

value - the value to be represented by the Long object.

Long

@Deprecated(since="9",
            forRemoval=true)
public Long(String s)
     throws NumberFormatException

Deprecated, for removal: This API element is subject to removal in a future version.

It is rarely appropriate to use this constructor. Use parseLong(String) to convert a string to a long primitive, or use valueOf(String) to convert a string to a Long object.

Constructs a newly allocated Long object that represents the long value indicated by the String parameter. The string is converted to a long value in exactly the manner used by the parseLong method for radix 10.

Parameters:

s - the String to be converted to a Long.

Throws:

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

Method Details

toString

public static String toString(long 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 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:

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:

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

Parameters:

i - a long 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(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.

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(long, int)

toHexString

public static String toHexString(long i)

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

The unsigned long value 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 leading 0s.

The value of the argument can be recovered from the returned string s by calling Long.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:

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:

Long.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 - a long to be converted to a string.

Returns:

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

Since:

1.0.2

See Also:

• HexFormat
• parseUnsignedLong(String, int)
• toUnsignedString(long, int)

toOctalString

public static String toOctalString(long i)

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

The unsigned long value 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 leading 0s.

The value of the argument can be recovered from the returned string s by calling Long.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:

01234567

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

Parameters:

i - a long to be converted to a string.

Returns:

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

Since:

1.0.2

See Also:

• parseUnsignedLong(String, int)
• toUnsignedString(long, int)

toBinaryString

public static String toBinaryString(long i)

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

The unsigned long value 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 leading 0s.

The value of the argument can be recovered from the returned string s by calling Long.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 - a long to be converted to a string.

Returns:

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

Since:

1.0.2

See Also:

• parseUnsignedLong(String, int)
• toUnsignedString(long, int)

toString

public static String toString(long i)

Returns a String object representing the specified long. 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 the toString(long, int) method.

Parameters:

i - a long to be converted.

Returns:

a string representation of the argument in base 10.

toUnsignedString

public static String toUnsignedString(long 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(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:

• toUnsignedString(long, int)

parseLong

public static long parseLong(String s,
 int radix)
                      throws NumberFormatException

Parses the string argument as a signed long 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 long value is returned.

Note that neither the character L ('\u004C') nor l ('\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 either L or l may appear as a digit for a radix greater than or equal to 22.

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 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 - the String containing the long representation to be parsed.

radix - the radix to be used while parsing s.

Returns:

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

Throws:

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

parseLong

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

Parses the CharSequence argument as a signed long 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 long 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 long 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 long in the specified radix, or if radix is either smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX.

Since:

9

parseLong

public static long parseLong(String s)
                      throws NumberFormatException

Parses the string argument as a signed decimal long. 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 long value is returned, exactly as if the argument and the radix 10 were given as arguments to the parseLong(java.lang.String, int) method.

Note that neither the character L ('\u004C') nor l ('\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 - a String containing the long representation to be parsed

Returns:

the long represented by the argument in decimal.

Throws:

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

parseUnsignedLong

public static long parseUnsignedLong(String s,
 int radix)
                              throws NumberFormatException

Parses the string argument as an unsigned long 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 long, 2⁶⁴-1.

Parameters:

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

radix - the radix to be used while parsing s.

Returns:

the unsigned long represented by the string argument in the specified radix.

Throws:

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

Since:

1.8

parseUnsignedLong

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

Parses the CharSequence argument as an unsigned long 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 long 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 long 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 long in the specified radix, or if radix is either smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX.

Since:

9

parseUnsignedLong

public static long parseUnsignedLong(String s)
                              throws NumberFormatException

Parses the string argument as an unsigned decimal long. 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 parseUnsignedLong(java.lang.String, int) method.

Parameters:

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

Returns:

the unsigned long value represented by the decimal string argument

Throws:

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

Since:

1.8

valueOf

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

Returns a Long 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 long in the radix specified by the second argument, exactly as if the arguments were given to the parseLong(java.lang.String, int) method. The result is a Long object that represents the long value specified by the string.

In other words, this method returns a Long object equal to the value of:

Long.valueOf(Long.parseLong(s, radix))

Parameters:

s - the string to be parsed

radix - the radix to be used in interpreting s

Returns:

a Long object holding the value represented by the string argument in the specified radix.

Throws:

NumberFormatException - If the String does not contain a parsable long.

valueOf

public static Long valueOf(String s)
                    throws NumberFormatException

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

In other words, this method returns a Long object equal to the value of:

Long.valueOf(Long.parseLong(s))

Parameters:

s - the string to be parsed.

Returns:

a Long object holding the value represented by the string argument.

Throws:

NumberFormatException - If the string cannot be parsed as a long.

valueOf

public static Long valueOf(long l)

Returns a Long instance representing the specified long value. If a new Long instance is not required, this method should generally be used in preference to the constructor Long(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 Long instance representing l.

Since:

1.5

decode

public static Long decode(String nm)
                   throws NumberFormatException

Decodes a String into a Long. 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 Long.parseLong 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:

a Long object holding the long value represented by nm

Throws:

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

Since:

1.2

See Also:

• parseLong(String, int)

byteValue

public byte byteValue()

Returns the value of this Long 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 Long 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 Long as an int after a narrowing primitive conversion.

Specified by:

intValue in class Number

Returns:

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

See Java Language Specification:

5.1.3 Narrowing Primitive Conversion

longValue

public long longValue()

Returns the value of this Long as a long value.

Specified by:

longValue in class Number

Returns:

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

floatValue

public float floatValue()

Returns the value of this Long 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 Long 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 Long's value. The value is converted to signed decimal representation and returned as a string, exactly as if the long value were given as an argument to the toString(long) 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 Long. The result is the exclusive OR of the two halves of the primitive long value held by this Long object. That is, the hashcode is the value of the expression:

(int)(this.longValue()^(this.longValue()>>>32))

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

See Also:

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

hashCode

public static int hashCode(long value)

Returns a hash code for a long value; compatible with Long.hashCode().

Parameters:

value - the value to hash

Returns:

a hash code value for a long 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 a Long object that contains the same long 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

getLong

public static Long getLong(String nm)

Determines the long 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 a long value using the grammar supported by decode and a Long 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 a Long object equal to the value of:

getLong(nm, null)

Parameters:

nm - property name.

Returns:

the Long 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)

getLong

public static Long getLong(String nm,
 long val)

Determines the long 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 a long value using the grammar supported by decode and a Long object representing this value is returned.

The second argument is the default value. A Long 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 a Long object equal to the value of:

getLong(nm, Long.valueOf(val))

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

 Long result = getLong(nm, null);
 return (result == null) ? Long.valueOf(val) : result;
 

to avoid the unnecessary allocation of a Long object when the default value is not needed.

Parameters:

nm - property name.

val - default value.

Returns:

the Long 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)

getLong

public static Long getLong(String nm,
 Long val)

Returns the long 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 a long value, as per the decode method, and a Long 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 for 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.

Note that, in every case, neither L ('\u004C') nor l ('\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 Long 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)

compareTo

public int compareTo(Long anotherLong)

Compares two Long objects numerically.

Specified by:

compareTo in interface Comparable<Long>

Parameters:

anotherLong - the Long to be compared.

Returns:

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

Since:

1.2

compare

public static int compare(long x,
 long y)

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

    Long.valueOf(x).compareTo(Long.valueOf(y))
 

Parameters:

x - the first long to compare

y - the second long 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(long x,
 long y)

Compares two long values numerically treating the values as unsigned.

Parameters:

x - the first long to compare

y - the second long 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

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 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(long, long)

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 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(long, long)

highestOneBit

public static long highestOneBit(long i)

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

a long 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 long lowestOneBit(long i)

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

a long 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(long i)

Returns the number of zero bits preceding the highest-order ("leftmost") one-bit in the two's complement binary representation of the specified long value. 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 long values 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 long value, or 64 if the value is equal to zero.

Since:

1.5

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 specified long value. 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 long value, 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 specified long 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 long value.

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 specified long 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 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 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 long value 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 specified long 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 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 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 long value 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 specified long value.

Parameters:

i - the value to be reversed

Returns:

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

Since:

1.5

compress

public static long compress(long i,
 long mask)

Returns the value obtained by compressing the bits of the specified long 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:

// Compressing drink to food
compress(0xCAFEBABEL, 0xFF00FFF0L) == 0xCABABL

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:

// 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 compressed

mask - the bit mask

Returns:

the compressed value

Since:

19

See Also:

• expand(long, long)

expand

public static long expand(long i,
 long mask)

Returns the value obtained by expanding the bits of the specified long 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:

expand(0x0000CABABL, 0xFF00FFF0L) == 0xCA00BAB0L

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:

// 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 & m

The select operation for determining the position of the one-bit with index n in a long value 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 expanded

mask - the bit mask

Returns:

the expanded value

Since:

19

See Also:

• compress(long, long)

signum

public static int signum(long i)

Returns the signum function of the specified long 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 long value.

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 specified long value.

Parameters:

i - the value whose bytes are to be reversed

Returns:

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

Since:

1.5

sum

public static long sum(long a,
 long b)

Adds two long values 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 long max(long a,
 long b)

Returns the greater of two long 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 long min(long a,
 long b)

Returns the smaller of two long 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<Long> 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 Long instance

Since:

12

resolveConstantDesc

public Long 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 Long instance

Since:

12