Module ch.randelshofer.fastdoubleparser

Package ch.randelshofer.fastdoubleparser

Class JavaDoubleParser

java.lang.Object

ch.randelshofer.fastdoubleparser.JavaDoubleParser

public final class JavaDoubleParser
extends java.lang.Object

Parses a double value; the supported syntax is compatible with Double.valueOf(String).

Syntax

Leading and trailing whitespace characters in the string are ignored. Whitespace is removed as if by the String.trim() method; that is, characters in the range [U+0000,U+0020].

The rest of string should constitute a Java FloatingPointLiteral as described by the lexical syntax rules shown below:

FloatingPointLiteral:

[Sign] NaN

[Sign] Infinity

[Sign] DecimalFloatingPointLiteral

[Sign] HexFloatingPointLiteral

HexFloatingPointLiteral:

HexSignificand BinaryExponent [FloatTypeSuffix]

HexSignificand:

HexNumeral

HexNumeral .

0x [HexDigits] . HexDigits

0X [HexDigits] . HexDigits

BinaryExponent:

BinaryExponentIndicator SignedInteger

BinaryExponentIndicator:

p

P

DecimalFloatingPointLiteral:

DecSignificand [DecExponent] [FloatTypeSuffix]

DecSignificand:

IntegerPart . [FractionPart]

. FractionPart

IntegerPart

IntegerPart:

Digits

FractionPart:

Digits

DecExponent:

ExponentIndicator [Sign] Digits

ExponentIndicator:

e

E

Sign:

++

-

Digits:

Digit {Digit}

Digit:

(one of)

0 1 2 3 4 5 6 7 8 9

HexNumeral:

0 x HexDigits

0 X HexDigits

HexDigits:

HexDigit {HexDigit}

HexDigit:

(one of)

0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F

FloatTypeSuffix:

(one of)

f F d D

Expected character lengths for values produced by Double.toString(double):

• DecSignificand (IntegerPart + FractionPart): 1 to 17 digits
• IntegerPart: 1 to 7 digits
• FractionPart: 1 to 16 digits
• SignedInteger in exponent: 1 to 3 digits
• FloatingPointLiteral: 1 to 24 characters, e.g. "-1.2345678901234568E-300"

Maximal input length supported by this parser:

• FloatingPointLiteral with or without white space around it: Integer.MAX_VALUE - 4 = 2,147,483,643 characters.

References:

The Java® Language Specification, Java SE 18 Edition, Chapter 3. Lexical Structure, 3.10.2. Floating-Point Literals

docs.oracle.com

Field Summary

Fields

Modifier and Type	Field	Description
private static JavaDoubleBitsFromByteArray	BYTE_ARRAY_PARSER
private static JavaDoubleBitsFromCharArray	CHAR_ARRAY_PARSER
private static JavaDoubleBitsFromCharSequence	CHAR_SEQUENCE_PARSER

Constructor Summary

Constructors

Modifier	Constructor	Description
private	JavaDoubleParser()	Don't let anyone instantiate this class.

Method Summary

Modifier and Type	Method	Description
static double	parseDouble(byte[] str)	Convenience method for calling parseDouble(byte[], int, int).
static double	parseDouble(byte[] str, int offset, int length)	Parses a FloatingPointLiteral from a byte-Array and converts it into a double value.
static double	parseDouble(char[] str)	Convenience method for calling parseDouble(char[], int, int).
static double	parseDouble(char[] str, int offset, int length)	Parses a FloatingPointLiteral from a byte-Array and converts it into a double value.
static double	parseDouble(java.lang.CharSequence str)	Convenience method for calling parseDouble(CharSequence, int, int).
static double	parseDouble(java.lang.CharSequence str, int offset, int length)	Parses a FloatingPointLiteral from a CharSequence and converts it into a double value.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BYTE_ARRAY_PARSER

private static final JavaDoubleBitsFromByteArray BYTE_ARRAY_PARSER

CHAR_ARRAY_PARSER

private static final JavaDoubleBitsFromCharArray CHAR_ARRAY_PARSER

CHAR_SEQUENCE_PARSER

private static final JavaDoubleBitsFromCharSequence CHAR_SEQUENCE_PARSER

Constructor Detail

JavaDoubleParser

private JavaDoubleParser()

Don't let anyone instantiate this class.

Method Detail

parseDouble

public static double parseDouble(java.lang.CharSequence str)
                          throws java.lang.NumberFormatException

Convenience method for calling parseDouble(CharSequence, int, int).

Parameters:

str - the string to be parsed

Returns:

the parsed value

Throws:

java.lang.NullPointerException - if the string is null

java.lang.NumberFormatException - if the string can not be parsed successfully

parseDouble

public static double parseDouble(java.lang.CharSequence str,
                                 int offset,
                                 int length)
                          throws java.lang.NumberFormatException

Parses a FloatingPointLiteral from a CharSequence and converts it into a double value.

Parameters:

str - the string to be parsed

offset - the start offset of the FloatingPointLiteral in str

length - the length of FloatingPointLiteral in str

Returns:

the parsed value

Throws:

java.lang.NullPointerException - if the string is null

java.lang.IllegalArgumentException - if offset or length are illegal

java.lang.NumberFormatException - if the string can not be parsed successfully

parseDouble

public static double parseDouble(byte[] str)
                          throws java.lang.NumberFormatException

Convenience method for calling parseDouble(byte[], int, int).

Parameters:

str - the string to be parsed, a byte array with characters in ISO-8859-1, ASCII or UTF-8 encoding

Returns:

the parsed value

Throws:

java.lang.NullPointerException - if the string is null

java.lang.IllegalArgumentException - if offset or length are illegal

java.lang.NumberFormatException - if the string can not be parsed successfully

parseDouble

public static double parseDouble(byte[] str,
                                 int offset,
                                 int length)
                          throws java.lang.NumberFormatException

Parses a FloatingPointLiteral from a byte-Array and converts it into a double value.

Parameters:

str - the string to be parsed, a byte array with characters in ISO-8859-1, ASCII or UTF-8 encoding

offset - The index of the first byte to parse

length - The number of bytes to parse

Returns:

the parsed value

Throws:

java.lang.NullPointerException - if the string is null

java.lang.IllegalArgumentException - if offset or length are illegal

java.lang.NumberFormatException - if the string can not be parsed successfully

parseDouble

public static double parseDouble(char[] str)
                          throws java.lang.NumberFormatException

Convenience method for calling parseDouble(char[], int, int).

Parameters:

str - the string to be parsed

Returns:

the parsed value

Throws:

java.lang.NullPointerException - if the string is null

java.lang.NumberFormatException - if the string can not be parsed successfully

parseDouble

public static double parseDouble(char[] str,
                                 int offset,
                                 int length)
                          throws java.lang.NumberFormatException

Parses a FloatingPointLiteral from a byte-Array and converts it into a double value.

See JavaDoubleParser for the syntax of FloatingPointLiteral.

Parameters:

str - the string to be parsed, a byte array with characters in ISO-8859-1, ASCII or UTF-8 encoding

offset - The index of the first character to parse

length - The number of characters to parse

Returns:

the parsed value

Throws:

java.lang.NullPointerException - if the string is null

java.lang.IllegalArgumentException - if offset or length are illegal

java.lang.NumberFormatException - if the string can not be parsed successfully