Java Doc for Long.java in  » 6.0-JDK-Core » lang » java » lang » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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 Long.highestOneBit(long) highestOneBit and Long.numberOfTrailingZeros(long) numberOfTrailingZeros ) are based on material from Henry S. Warren, Jr.'s Hacker's Delight, (Addison Wesley, 2002).
author:
   Lee Boynton
author:
   Arthur van Hoff
author:
   Josh Bloch
author:
   Joseph D. Darcy
version:
   1.91, 07/12/07
since:
   JDK1.0

DecodableString:

Sign_opt DecimalNumeral

Sign_opt 0x HexDigits

Sign_opt 0X HexDigits

Sign_opt # HexDigits

Sign_opt 0 OctalDigits

Sign:

-

+

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 first argument is treated as the name of a system property. System properties are accessible through the java.lang.System.getProperty(java.lang.String) method.

The first argument is treated as the name of a system property. System properties are accessible through the java.lang.System.getProperty(java.lang.String) method.

The unsigned long value is the argument plus 2⁶⁴ if the argument is negative; otherwise, it is equal to the argument.

The unsigned long value is the argument plus 2⁶⁴ if the argument is negative; otherwise, it is equal to the argument.

The unsigned long value is the argument plus 2⁶⁴ if the argument is negative; otherwise, it is equal to the 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').

DecodableString:

Sign_opt DecimalNumeral

Sign_opt 0x HexDigits

Sign_opt 0X HexDigits

Sign_opt # HexDigits

Sign_opt 0 OctalDigits

Sign:

-

+

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. a Long object holding the long value represented by nm
throws:
  NumberFormatException - if the String does notcontain a parsable long .
See Also:   java.lang.Long.parseLong(Stringint)
since:
   1.2

The first argument is treated as the name of a system property. System properties are accessible through the java.lang.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)

The first argument is treated as the name of a system property. System properties are accessible through the java.lang.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))

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

• 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:
  nm - property name.
Parameters:
  val - default value. the Long value of the property.
See Also:   java.lang.System.getProperty(java.lang.String)
See Also:   java.lang.System.getProperty(java.lang.Stringjava.lang.String)
See Also:   java.lang.Long.decode

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

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)

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 java.lang.Character.MIN_RADIX or larger than java.lang.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
 

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 the long represented by the argument in decimal.
throws:
  NumberFormatException - if the string does not contain aparsable long .

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) . the value obtained by rotating the two's complement binaryrepresentation of the specified long value left by thespecified number of bits.
since:
   1.5

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) . the value obtained by rotating the two's complement binaryrepresentation of the specified long value right by thespecified number of bits.
since:
   1.5

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 0 s. 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. the string representation of the unsigned long value represented by the argument in binary (base 2).
since:
   JDK 1.0.2

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 hexadecimal (base 16) with no extra leading 0 s. 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

Long.toHexString(n).toUpperCase()

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 0 s.

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

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

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

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

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

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

new Long(Long.parseLong(s))