Returns a
Float
object holding the
float
value represented by the argument string
s
.
If s
is null
, then a
NullPointerException
is thrown.
Leading and trailing whitespace characters in s
are ignored. Whitespace is removed as if by the String.trim()
method; that is, both ASCII space and control
characters are removed. The rest of s
should
constitute a FloatValue as described by the lexical
syntax rules:
- FloatValue:
- Signopt
NaN
- Signopt
Infinity
- Signopt FloatingPointLiteral
- Signopt HexFloatingPointLiteral
- SignedInteger
- HexFloatingPointLiteral:
- HexSignificand BinaryExponent FloatTypeSuffixopt
- HexSignificand:
- HexNumeral
- HexNumeral
.
0x
HexDigitsopt
.
HexDigits
0X
HexDigitsopt
.
HexDigits
- BinaryExponent:
- BinaryExponentIndicator SignedInteger
- BinaryExponentIndicator:
p
P
where
Sign,
FloatingPointLiteral,
HexNumeral,
HexDigits,
SignedInteger and
FloatTypeSuffix are as defined in the lexical structure
sections of the of the
Java Language
Specification. If
s
does not have the form of
a
FloatValue, then a
NumberFormatException
is thrown. Otherwise,
s
is regarded as
representing an exact decimal value in the usual
"computerized scientific notation" or as an exact
hexadecimal value; this exact numerical value is then
conceptually converted to an "infinitely precise"
binary value that is then rounded to type
float
by the usual round-to-nearest rule of IEEE 754 floating-point
arithmetic, which includes preserving the sign of a zero
value. Finally, a
Float
object representing this
float
value is returned.
To interpret localized string representations of a
floating-point value, use subclasses of NumberFormat
.
Note that trailing format specifiers, specifiers that
determine the type of a floating-point literal
(1.0f
is a float
value;
1.0d
is a double
value), do
not influence the results of this method. In other
words, the numerical value of the input string is converted
directly to the target floating-point type. In general, the
two-step sequence of conversions, string to double
followed by double
to float
, is
not equivalent to converting a string directly to
float
. For example, if first converted to an
intermediate double
and then to
float
, the string
"1.00000017881393421514957253748434595763683319091796875001d"
results in the float
value
1.0000002f
; if the string is converted directly to
float
, 1.0000001f
results.
To avoid calling this method on an invalid string and having
a NumberFormatException
be thrown, the documentation
for Double.valueOf
lists a regular
expression which can be used to screen the input.
Returns:
a Float
object holding the value
represented by the String
argument.
Parameters:
- s - the string to be parsed.
Throws:
- NumberFormatException - if the string does not contain a
parsable number.