Class: java.lang.Long

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.

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).

Authors:
@author Lee Boynton
@author Arthur van Hoff
@author Josh Bloch
@author Joseph D. Darcy
Since:
@since JDK1.0

Inheritance

Superclass tree: Implements:

Methods

  • Longtop

    public Long(long value)
    Constructs a newly allocated Long object that represents the specified long argument.
    Parameters:
    @param value the value to be represented by the Long object.
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  • Longtop

    public Long(String s) throws NumberFormatException
    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:
    @param s the String to be converted to a Long .
    Exceptions:
    @throws NumberFormatException if the String does not contain a parsable long .
    See:
    @see Long.parseLong(java.lang.String, int)
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  • bitCounttop

    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.
    Return:
    @return the number of one-bits in the two's complement binary representation of the specified long value.
    Since:
    @since 1.5
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  • byteValuetop

    public byte byteValue()
    Returns the value of this Long as a byte.
    Return:
    @return the numeric value represented by this object after conversion to type byte.
    Override hierarchy:
    byteValue from Number
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  • compareTotop

    public int compareTo(Long anotherLong)
    Compares two Long objects numerically.
    Parameters:
    @param anotherLong the Long to be compared.
    Return:
    @return 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:
    @since 1.2
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  • decodetop

    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:
    Signopt DecimalNumeral
    Signopt 0x HexDigits
    Signopt 0X HexDigits
    Signopt # HexDigits
    Signopt 0 OctalDigits

    Sign:
    -
    DecimalNumeral, HexDigits, and OctalDigits are defined in §3.10.1 of the Java Language Specification.

    The sequence of characters following an (optional) negative 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:
    @param nm the String to decode.
    Return:
    @return a Long object holding the long value represented by nm
    Exceptions:
    @throws NumberFormatException if the String does not contain a parsable long .
    See:
    @see Long.parseLong(java.lang.String, int)
    Since:
    @since 1.2
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  • doubleValuetop

    public double doubleValue()
    Returns the value of this Long as a double.
    Return:
    @return the numeric value represented by this object after conversion to type double.
    Override hierarchy:
    doubleValue from Number
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  • equalstop

    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.
    Parameters:
    @param obj the object to compare with.
    Return:
    @return true if the objects are the same; false otherwise.
    Override hierarchy:
    equals from Object
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  • floatValuetop

    public float floatValue()
    Returns the value of this Long as a float.
    Return:
    @return the numeric value represented by this object after conversion to type float.
    Override hierarchy:
    floatValue from Number
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  • getCharstop

    static void getChars(long i, int index, char[] buf)
    Places characters representing the integer i into the character array buf. The characters are placed into the buffer backwards starting with the least significant digit at the specified index (exclusive), and working backwards from there. Will fail if i == Long.MIN_VALUE
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  • getLongtop

    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 and a Long object representing this value is returned. Details of possible numeric formats can be found with the definition of getProperty.

    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:
    @param nm property name.
    Return:
    @return the Long value of the property.
    See:
    @see System.getProperty(java.lang.String)
    @see System.getProperty(java.lang.String, java.lang.String)
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  • getLongtop

    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 and a Long object representing this value is returned. Details of possible numeric formats can be found with the definition of getProperty.

    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, new Long(val))
    but in practice it may be implemented in a manner such as: 
     Long result = getLong(nm, null);
 return (result == null) ? new Long(val) : result;
    to avoid the unnecessary allocation of a Long object when the default value is not needed.
    Parameters:
    @param nm property name.
    @param val default value.
    Return:
    @return the Long value of the property.
    See:
    @see System.getProperty(java.lang.String)
    @see System.getProperty(java.lang.String, java.lang.String)
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  • getLongtop

    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 Long.decode method, and a Long object representing this value is returned.
    • 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 Long.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 Long.valueOf(java.lang.String, int) with radix 8.
    • Otherwise the property value is parsed as a decimal integer exactly as by the method Long.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:
    @param nm property name.
    @param val default value.
    Return:
    @return the Long value of the property.
    See:
    @see System.getProperty(java.lang.String)
    @see System.getProperty(java.lang.String, java.lang.String)
    @see Long.decode(java.lang.String)
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  • hashCodetop

    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))
    Return:
    @return a hash code value for this object.
    Override hierarchy:
    hashCode from Object
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  • highestOneBittop

    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.
    Return:
    @return 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:
    @since 1.5
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  • intValuetop

    public int intValue()
    Returns the value of this Long as an int.
    Return:
    @return the numeric value represented by this object after conversion to type int.
    Override hierarchy:
    intValue from Number
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  • longValuetop

    public long longValue()
    Returns the value of this Long as a long value.
    Return:
    @return the numeric value represented by this object after conversion to type long.
    Override hierarchy:
    longValue from Number
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  • lowestOneBittop

    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.
    Return:
    @return 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:
    @since 1.5
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  • numberOfLeadingZerostop

    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)
    Return:
    @return 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:
    @since 1.5
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  • numberOfTrailingZerostop

    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.
    Return:
    @return 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:
    @since 1.5
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  • parseLongtop

    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. The resulting long value is returned, exactly as if the argument and the radix 10 were given as arguments to the Long.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:
    @param s a String containing the long representation to be parsed
    Return:
    @return the long represented by the argument in decimal.
    Exceptions:
    @throws NumberFormatException if the string does not contain a parsable long .
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  • parseLongtop

    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. 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 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') 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("-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:
    @param s the String containing the long representation to be parsed.
    @param radix the radix to be used while parsing s .
    Return:
    @return the long represented by the string argument in the specified radix.
    Exceptions:
    @throws NumberFormatException if the string does not contain a parsable long .
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  • reversetop

    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.
    Return:
    @return the value obtained by reversing order of the bits in the specified long value.
    Since:
    @since 1.5
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  • reverseBytestop

    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.
    Return:
    @return the value obtained by reversing the bytes in the specified long value.
    Since:
    @since 1.5
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  • rotateLefttop

    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).

    Return:
    @return the value obtained by rotating the two's complement binary representation of the specified long value left by the specified number of bits.
    Since:
    @since 1.5
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  • rotateRighttop

    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).

    Return:
    @return the value obtained by rotating the two's complement binary representation of the specified long value right by the specified number of bits.
    Since:
    @since 1.5
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  • shortValuetop

    public short shortValue()
    Returns the value of this Long as a short.
    Return:
    @return the numeric value represented by this object after conversion to type short.
    Override hierarchy:
    shortValue from Number
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  • signumtop

    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.)
    Return:
    @return the signum function of the specified long value.
    Since:
    @since 1.5
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  • stringSizetop

    static int stringSize(long x)
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  • toBinaryStringtop

    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. 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:
    @param i a long to be converted to a string.
    Return:
    @return the string representation of the unsigned long value represented by the argument in binary (base 2).
    Since:
    @since JDK 1.0.2
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  • toHexStringtop

    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. 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()
    Parameters:
    @param i a long to be converted to a string.
    Return:
    @return the string representation of the unsigned long value represented by the argument in hexadecimal (base 16).
    Since:
    @since JDK 1.0.2
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  • toOctalStringtop

    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.

    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:
    @param i a long to be converted to a string.
    Return:
    @return the string representation of the unsigned long value represented by the argument in octal (base 8).
    Since:
    @since JDK 1.0.2
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  • toStringtop

    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 Long.toString(long) method.
    Return:
    @return a string representation of the value of this object in base 10.
    Override hierarchy:
    toString from Object
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  • toStringtop

    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 Long.toString(long, int) method.
    Parameters:
    @param i a long to be converted.
    Return:
    @return a string representation of the argument in base 10.
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  • toStringtop

    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:
    @param i a long to be converted to a string.
    @param radix the radix to use in the string representation.
    Return:
    @return a string representation of the argument in the specified radix.
    See:
    @see Character.MAX_RADIX
    @see Character.MIN_RADIX
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  • toUnsignedStringtop

    static private String toUnsignedString(long i, int shift)
    Convert the integer to an unsigned number.
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  • valueOftop

    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(long), as this method is likely to yield significantly better space and time performance by caching frequently requested values.
    Parameters:
    @param l a long value.
    Return:
    @return a Long instance representing l .
    Since:
    @since 1.5
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  • valueOftop

    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 Long.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:

    new Long(Long.parseLong(s))
    Parameters:
    @param s the string to be parsed.
    Return:
    @return a Long object holding the value represented by the string argument.
    Exceptions:
    @throws NumberFormatException If the string cannot be parsed as a long .
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  • valueOftop

    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 Long.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:

    new Long(Long.parseLong(s, radix))
    Parameters:
    @param s the string to be parsed
    @param radix the radix to be used in interpreting s
    Return:
    @return a Long object holding the value represented by the string argument in the specified radix.
    Exceptions:
    @throws NumberFormatException If the String does not contain a parsable long .
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Fields

  • MAX_VALUE

    public static final long MAX_VALUE = 9223372036854775807
    A constant holding the maximum value a long can have, 263-1.

  • MIN_VALUE

    public static final long MIN_VALUE = -9223372036854775808
    A constant holding the minimum value a long can have, -263.

  • SIZE

    public static final int SIZE = 64
    The number of bits used to represent a long value in two's complement binary form.

  • TYPE

    public static final Class<Long> TYPE
    The Class instance representing the primitive type long.

  • serialVersionUID

    static final private long serialVersionUID = 4290774380558885855
    use serialVersionUID from JDK 1.0.2 for interoperability

  • value

    final private long value
    The value of the Long.