Java как использовать 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).

Field Summary

Constructor Summary

Constructs a newly allocated Long object that represents the long value indicated by the String parameter.

Method Summary

Returns the number of one-bits in the two’s complement binary representation of the specified long value.

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

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 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 the number of zero bits preceding the highest-order («leftmost») one-bit in the two’s complement binary representation of the specified long value.

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

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

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

Returns the value obtained by rotating the two’s complement binary representation of the specified long value left by the specified number of bits.

Returns the value obtained by rotating the two’s complement binary representation of the specified long value right by the specified number of bits.

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

Returns a Long object holding the value extracted from the specified String when parsed with the radix given by the second argument.

Methods inherited from class java.lang.Object

Field Detail

MIN_VALUE

@Native public static final long MIN_VALUE

MAX_VALUE

@Native public static final long MAX_VALUE

TYPE

SIZE

@Native public static final int SIZE

BYTES

public static final int BYTES

Constructor Detail

Long

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.

Method Detail

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_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:

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:

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 .

toHexString

Returns a string representation of the long argument as an unsigned integer in base 16. The unsigned long value is the argument plus 2 64 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. 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:

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:

toOctalString

Returns a string representation of the long argument as an unsigned integer in base 8. The unsigned long value is the argument plus 2 64 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. 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:

toBinaryString

Returns a string representation of the long argument as an unsigned integer in base 2. The unsigned long value is the argument plus 2 64 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. 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.

toString

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.

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 the toUnsignedString(long, int) method.

parseLong

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

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 .

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

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.

parseUnsignedLong

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

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 , 2 64 -1.

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 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.

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:

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:

valueOf

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. Note that unlike the corresponding method in the Integer class, this method is not required to cache values within a particular range.

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 .

byteValue

shortValue

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