Float
public
final
class
Float
extends Number
implements
Comparable<Float>
java.lang.Object  
↳  java.lang.Number  
↳  java.lang.Float 
The Float
class wraps a value of primitive type
float
in an object. An object of type
Float
contains a single field whose type is
float
.
In addition, this class provides several methods for converting a
float
to a String
and a
String
to a float
, as well as other
constants and methods useful when dealing with a
float
.
Summary
Constants  

int 
BYTES
The number of bytes used to represent a 
int 
MAX_EXPONENT
Maximum exponent a finite 
float 
MAX_VALUE
A constant holding the largest positive finite value of type

int 
MIN_EXPONENT
Minimum exponent a normalized 
float 
MIN_NORMAL
A constant holding the smallest positive normal value of type

float 
MIN_VALUE
A constant holding the smallest positive nonzero value of type

float 
NEGATIVE_INFINITY
A constant holding the negative infinity of type

float 
NaN
A constant holding a NotaNumber (NaN) value of type

float 
POSITIVE_INFINITY
A constant holding the positive infinity of type

int 
SIZE
The number of bits used to represent a 
Fields  

public
static
final
Class<Float> 
TYPE
The 
Public constructors  

Float(float value)
Constructs a newly allocated 

Float(double value)
Constructs a newly allocated 

Float(String s)
Constructs a newly allocated 
Public methods  

byte

byteValue()
Returns the value of this 
static
int

compare(float f1, float f2)
Compares the two specified 
int

compareTo(Float anotherFloat)
Compares two 
double

doubleValue()
Returns the value of this 
boolean

equals(Object obj)
Compares this object against the specified object. 
static
int

floatToIntBits(float value)
Returns a representation of the specified floatingpoint value according to the IEEE 754 floatingpoint "single format" bit layout. 
static
int

floatToRawIntBits(float value)
Returns a representation of the specified floatingpoint value according to the IEEE 754 floatingpoint "single format" bit layout, preserving NotaNumber (NaN) values. 
float

floatValue()
Returns the 
int

hashCode()
Returns a hash code for this 
static
int

hashCode(float value)
Returns a hash code for a 
static
float

intBitsToFloat(int bits)
Returns the 
int

intValue()
Returns the value of this 
static
boolean

isFinite(float f)
Returns 
boolean

isInfinite()
Returns 
static
boolean

isInfinite(float v)
Returns 
static
boolean

isNaN(float v)
Returns 
boolean

isNaN()
Returns 
long

longValue()
Returns value of this 
static
float

max(float a, float b)
Returns the greater of two 
static
float

min(float a, float b)
Returns the smaller of two 
static
float

parseFloat(String s)
Returns a new 
short

shortValue()
Returns the value of this 
static
float

sum(float a, float b)
Adds two 
static
String

toHexString(float f)
Returns a hexadecimal string representation of the

String

toString()
Returns a string representation of this 
static
String

toString(float f)
Returns a string representation of the 
static
Float

valueOf(String s)
Returns a 
static
Float

valueOf(float f)
Returns a 
Inherited methods  

Constants
BYTES
int BYTES
The number of bytes used to represent a float
value.
Constant Value: 4 (0x00000004)
MAX_EXPONENT
int MAX_EXPONENT
Maximum exponent a finite float
variable may have. It
is equal to the value returned by Math.getExponent(Float.MAX_VALUE)
.
Constant Value: 127 (0x0000007f)
MAX_VALUE
float MAX_VALUE
A constant holding the largest positive finite value of type
float
, (22^{23})·2^{127}.
It is equal to the hexadecimal floatingpoint literal
0x1.fffffeP+127f
and also equal to
Float.intBitsToFloat(0x7f7fffff)
.
Constant Value: 3.4028235E38
MIN_EXPONENT
int MIN_EXPONENT
Minimum exponent a normalized float
variable may have.
It is equal to the value returned by Math.getExponent(Float.MIN_NORMAL)
.
Constant Value: 126 (0xffffff82)
MIN_NORMAL
float MIN_NORMAL
A constant holding the smallest positive normal value of type
float
, 2^{126}. It is equal to the
hexadecimal floatingpoint literal 0x1.0p126f
and also
equal to Float.intBitsToFloat(0x00800000)
.
Constant Value: 1.17549435E38
MIN_VALUE
float MIN_VALUE
A constant holding the smallest positive nonzero value of type
float
, 2^{149}. It is equal to the
hexadecimal floatingpoint literal 0x0.000002P126f
and also equal to Float.intBitsToFloat(0x1)
.
Constant Value: 1.4E45
NEGATIVE_INFINITY
float NEGATIVE_INFINITY
A constant holding the negative infinity of type
float
. It is equal to the value returned by
Float.intBitsToFloat(0xff800000)
.
Constant Value: Infinity
NaN
float NaN
A constant holding a NotaNumber (NaN) value of type
float
. It is equivalent to the value returned by
Float.intBitsToFloat(0x7fc00000)
.
Constant Value: NaN
POSITIVE_INFINITY
float POSITIVE_INFINITY
A constant holding the positive infinity of type
float
. It is equal to the value returned by
Float.intBitsToFloat(0x7f800000)
.
Constant Value: Infinity
SIZE
int SIZE
The number of bits used to represent a float
value.
Constant Value: 32 (0x00000020)
Fields
TYPE
Class<Float> TYPE
The Class
instance representing the primitive type
float
.
Public constructors
Float
Float (float value)
Constructs a newly allocated Float
object that
represents the primitive float
argument.
Parameters  

value 
float : the value to be represented by the Float .

Float
Float (double value)
Constructs a newly allocated Float
object that
represents the argument converted to type float
.
Parameters  

value 
double : the value to be represented by the Float .

Float
Float (String s)
Constructs a newly allocated Float
object that
represents the floatingpoint value of type float
represented by the string. The string is converted to a
float
value as if by the valueOf
method.
Parameters  

s 
String : a string to be converted to a Float . 
Throws  

NumberFormatException 
if the string does not contain a parsable number. 
See also:
Public methods
byteValue
byte byteValue ()
Returns the value of this Float
as a byte
after
a narrowing primitive conversion.
Returns  

byte 
the float value represented by this object
converted to type byte 
compare
int compare (float f1, float f2)
Compares the two specified float
values. The sign
of the integer value returned is the same as that of the
integer that would be returned by the call:
new Float(f1).compareTo(new Float(f2))
Parameters  

f1 
float : the first float to compare. 
f2 
float : the second float to compare. 
Returns  

int 
the value 0 if f1 is
numerically equal to f2 ; a value less than
0 if f1 is numerically less than
f2 ; and a value greater than 0
if f1 is numerically greater than
f2 . 
compareTo
int compareTo (Float anotherFloat)
Compares two Float
objects numerically. There are
two ways in which comparisons performed by this method differ
from those performed by the Java language numerical comparison
operators (<, <=, ==, >=, >
) when
applied to primitive float
values:

Float.NaN
is considered by this method to be equal to itself and greater than all otherfloat
values (includingFloat.POSITIVE_INFINITY
). 
0.0f
is considered by this method to be greater than0.0f
.
Float
objects imposed by this method is consistent with equals.
Parameters  

anotherFloat 
Float : the Float to be compared. 
Returns  

int 
the value 0 if anotherFloat is
numerically equal to this Float ; a value
less than 0 if this Float
is numerically less than anotherFloat ;
and a value greater than 0 if this
Float is numerically greater than
anotherFloat . 
See also:
doubleValue
double doubleValue ()
Returns the value of this Float
as a double
after a widening primitive conversion.
Returns  

double 
the float value represented by this
object converted to type double 
equals
boolean equals (Object obj)
Compares this object against the specified object. The result
is true
if and only if the argument is not
null
and is a Float
object that
represents a float
with the same value as the
float
represented by this object. For this
purpose, two float
values are considered to be the
same if and only if the method floatToIntBits(float)
returns the identical int
value when applied to
each.
Note that in most cases, for two instances of class
Float
, f1
and f2
, the value
of f1.equals(f2)
is true
if and only if
f1.floatValue() == f2.floatValue()
also has the value true
. However, there are two exceptions:
 If
f1
andf2
both representFloat.NaN
, then theequals
method returnstrue
, even thoughFloat.NaN==Float.NaN
has the valuefalse
.  If
f1
represents+0.0f
whilef2
represents0.0f
, or vice versa, theequal
test has the valuefalse
, even though0.0f==0.0f
has the valuetrue
.
Parameters  

obj 
Object : the object to be compared 
Returns  

boolean 
true if the objects are the same;
false otherwise. 
See also:
floatToIntBits
int floatToIntBits (float value)
Returns a representation of the specified floatingpoint value according to the IEEE 754 floatingpoint "single format" bit layout.
Bit 31 (the bit that is selected by the mask
0x80000000
) represents the sign of the floatingpoint
number.
Bits 3023 (the bits that are selected by the mask
0x7f800000
) represent the exponent.
Bits 220 (the bits that are selected by the mask
0x007fffff
) represent the significand (sometimes called
the mantissa) of the floatingpoint number.
If the argument is positive infinity, the result is
0x7f800000
.
If the argument is negative infinity, the result is
0xff800000
.
If the argument is NaN, the result is 0x7fc00000
.
In all cases, the result is an integer that, when given to the
intBitsToFloat(int)
method, will produce a floatingpoint
value the same as the argument to floatToIntBits
(except all NaN values are collapsed to a single
"canonical" NaN value).
Parameters  

value 
float : a floatingpoint number. 
Returns  

int 
the bits that represent the floatingpoint number. 
floatToRawIntBits
int floatToRawIntBits (float value)
Returns a representation of the specified floatingpoint value according to the IEEE 754 floatingpoint "single format" bit layout, preserving NotaNumber (NaN) values.
Bit 31 (the bit that is selected by the mask
0x80000000
) represents the sign of the floatingpoint
number.
Bits 3023 (the bits that are selected by the mask
0x7f800000
) represent the exponent.
Bits 220 (the bits that are selected by the mask
0x007fffff
) represent the significand (sometimes called
the mantissa) of the floatingpoint number.
If the argument is positive infinity, the result is
0x7f800000
.
If the argument is negative infinity, the result is
0xff800000
.
If the argument is NaN, the result is the integer representing
the actual NaN value. Unlike the floatToIntBits
method, floatToRawIntBits
does not collapse all the
bit patterns encoding a NaN to a single "canonical"
NaN value.
In all cases, the result is an integer that, when given to the
intBitsToFloat(int)
method, will produce a
floatingpoint value the same as the argument to
floatToRawIntBits
.
Parameters  

value 
float : a floatingpoint number. 
Returns  

int 
the bits that represent the floatingpoint number. 
floatValue
float floatValue ()
Returns the float
value of this Float
object.
Returns  

float 
the float value represented by this object

hashCode
int hashCode ()
Returns a hash code for this Float
object. The
result is the integer bit representation, exactly as produced
by the method floatToIntBits(float)
, of the primitive
float
value represented by this Float
object.
Returns  

int 
a hash code value for this object. 
hashCode
int hashCode (float value)
Returns a hash code for a float
value; compatible with
Float.hashCode()
.
Parameters  

value 
float : the value to hash 
Returns  

int 
a hash code value for a float value. 
intBitsToFloat
float intBitsToFloat (int bits)
Returns the float
value corresponding to a given
bit representation.
The argument is considered to be a representation of a
floatingpoint value according to the IEEE 754 floatingpoint
"single format" bit layout.
If the argument is 0x7f800000
, the result is positive
infinity.
If the argument is 0xff800000
, the result is negative
infinity.
If the argument is any value in the range
0x7f800001
through 0x7fffffff
or in
the range 0xff800001
through
0xffffffff
, the result is a NaN. No IEEE 754
floatingpoint operation provided by Java can distinguish
between two NaN values of the same type with different bit
patterns. Distinct values of NaN are only distinguishable by
use of the Float.floatToRawIntBits
method.
In all other cases, let s, e, and m be three values that can be computed from the argument:
Then the floatingpoint result equals the value of the mathematical expression s·m·2^{e150}.int s = ((bits >> 31) == 0) ? 1 : 1; int e = ((bits >> 23) & 0xff); int m = (e == 0) ? (bits & 0x7fffff) << 1 : (bits & 0x7fffff)  0x800000;
Note that this method may not be able to return a
float
NaN with exactly same bit pattern as the
int
argument. IEEE 754 distinguishes between two
kinds of NaNs, quiet NaNs and signaling NaNs. The
differences between the two kinds of NaN are generally not
visible in Java. Arithmetic operations on signaling NaNs turn
them into quiet NaNs with a different, but often similar, bit
pattern. However, on some processors merely copying a
signaling NaN also performs that conversion. In particular,
copying a signaling NaN to return it to the calling method may
perform this conversion. So intBitsToFloat
may
not be able to return a float
with a signaling NaN
bit pattern. Consequently, for some int
values,
floatToRawIntBits(intBitsToFloat(start))
may
not equal start
. Moreover, which
particular bit patterns represent signaling NaNs is platform
dependent; although all NaN bit patterns, quiet or signaling,
must be in the NaN range identified above.
Parameters  

bits 
int : an integer. 
Returns  

float 
the float floatingpoint value with the same bit
pattern.

intValue
int intValue ()
Returns the value of this Float
as an int
after
a narrowing primitive conversion.
Returns  

int 
the float value represented by this object
converted to type int 
isFinite
boolean isFinite (float f)
Returns true
if the argument is a finite floatingpoint
value; returns false
otherwise (for NaN and infinity
arguments).
Parameters  

f 
float : the float value to be tested 
Returns  

boolean 
true if the argument is a finite
floatingpoint value, false otherwise. 
isInfinite
boolean isInfinite ()
Returns true
if this Float
value is
infinitely large in magnitude, false
otherwise.
Returns  

boolean 
true if the value represented by this object is
positive infinity or negative infinity;
false otherwise.

isInfinite
boolean isInfinite (float v)
Returns true
if the specified number is infinitely
large in magnitude, false
otherwise.
Parameters  

v 
float : the value to be tested. 
Returns  

boolean 
true if the argument is positive infinity or
negative infinity; false otherwise.

isNaN
boolean isNaN (float v)
Returns true
if the specified number is a
NotaNumber (NaN) value, false
otherwise.
Parameters  

v 
float : the value to be tested. 
Returns  

boolean 
true if the argument is NaN;
false otherwise.

isNaN
boolean isNaN ()
Returns true
if this Float
value is a
NotaNumber (NaN), false
otherwise.
Returns  

boolean 
true if the value represented by this object is
NaN; false otherwise.

longValue
long longValue ()
Returns value of this Float
as a long
after a
narrowing primitive conversion.
Returns  

long 
the float value represented by this object
converted to type long 
max
float max (float a, float b)
Returns the greater of two float
values
as if by calling Math.max
.
Parameters  

a 
float : the first operand 
b 
float : the second operand 
Returns  

float 
the greater of a and b 
See also:
min
float min (float a, float b)
Returns the smaller of two float
values
as if by calling Math.min
.
Parameters  

a 
float : the first operand 
b 
float : the second operand 
Returns  

float 
the smaller of a and b 
See also:
parseFloat
float parseFloat (String s)
Returns a new float
initialized to the value
represented by the specified String
, as performed
by the valueOf
method of class Float
.
Parameters  

s 
String : the string to be parsed. 
Returns  

float 
the float value represented by the string
argument. 
Throws  

NullPointerException 
if the string is null 
NumberFormatException 
if the string does not contain a
parsable float . 
See also:
shortValue
short shortValue ()
Returns the value of this Float
as a short
after a narrowing primitive conversion.
Returns  

short 
the float value represented by this object
converted to type short 
sum
float sum (float a, float b)
Adds two float
values together as per the + operator.
Parameters  

a 
float : the first operand 
b 
float : the second operand 
Returns  

float 
the sum of a and b 
See also:
toHexString
String toHexString (float f)
Returns a hexadecimal string representation of the
float
argument. All characters mentioned below are
ASCII characters.
 If the argument is NaN, the result is the string
"
NaN
".  Otherwise, the result is a string that represents the sign and
magnitude (absolute value) of the argument. If the sign is negative,
the first character of the result is '

' ('\u002D'
); if the sign is positive, no sign character appears in the result. As for the magnitude m: If m is infinity, it is represented by the string
"Infinity"
; thus, positive infinity produces the result"Infinity"
and negative infinity produces the result"Infinity"
.  If m is zero, it is represented by the string
"0x0.0p0"
; thus, negative zero produces the result"0x0.0p0"
and positive zero produces the result"0x0.0p0"
.  If m is a
float
value with a normalized representation, substrings are used to represent the significand and exponent fields. The significand is represented by the characters"0x1."
followed by a lowercase hexadecimal representation of the rest of the significand as a fraction. Trailing zeros in the hexadecimal representation are removed unless all the digits are zero, in which case a single zero is used. Next, the exponent is represented by"p"
followed by a decimal string of the unbiased exponent as if produced by a call toInteger.toString
on the exponent value.  If m is a
float
value with a subnormal representation, the significand is represented by the characters"0x0."
followed by a hexadecimal representation of the rest of the significand as a fraction. Trailing zeros in the hexadecimal representation are removed. Next, the exponent is represented by"p126"
. Note that there must be at least one nonzero digit in a subnormal significand.
 If m is infinity, it is represented by the string
Floatingpoint Value  Hexadecimal String 

1.0  0x1.0p0 
1.0  0x1.0p0 
2.0  0x1.0p1 
3.0  0x1.8p1 
0.5  0x1.0p1 
0.25  0x1.0p2 
Float.MAX_VALUE 
0x1.fffffep127 
Minimum Normal Value 
0x1.0p126 
Maximum Subnormal Value 
0x0.fffffep126 
Float.MIN_VALUE 
0x0.000002p126 
Parameters  

f 
float : the float to be converted. 
Returns  

String 
a hex string representation of the argument. 
toString
String toString ()
Returns a string representation of this Float
object.
The primitive float
value represented by this object
is converted to a String
exactly as if by the method
toString
of one argument.
Returns  

String 
a String representation of this object. 
See also:
toString
String toString (float f)
Returns a string representation of the float
argument. All characters mentioned below are ASCII characters.
 If the argument is NaN, the result is the string
"
NaN
".  Otherwise, the result is a string that represents the sign and
magnitude (absolute value) of the argument. If the sign is
negative, the first character of the result is
'

' ('\u002D'
); if the sign is positive, no sign character appears in the result. As for the magnitude m: If m is infinity, it is represented by the characters
"Infinity"
; thus, positive infinity produces the result"Infinity"
and negative infinity produces the result"Infinity"
.  If m is zero, it is represented by the characters
"0.0"
; thus, negative zero produces the result"0.0"
and positive zero produces the result"0.0"
.  If m is greater than or equal to 10^{3} but
less than 10^{7}, then it is represented as the
integer part of m, in decimal form with no leading
zeroes, followed by '
.
' ('\u002E'
), followed by one or more decimal digits representing the fractional part of m.  If m is less than 10^{3} or greater than or
equal to 10^{7}, then it is represented in
socalled "computerized scientific notation." Let n
be the unique integer such that 10^{n }≤
m < 10^{n+1}; then let a
be the mathematically exact quotient of m and
10^{n} so that 1 ≤ a < 10.
The magnitude is then represented as the integer part of
a, as a single decimal digit, followed by
'
.
' ('\u002E'
), followed by decimal digits representing the fractional part of a, followed by the letter 'E
' ('\u0045'
), followed by a representation of n as a decimal integer, as produced by the methodtoString(int)
.
 If m is infinity, it is represented by the characters
float
. That is, suppose that x is the
exact mathematical value represented by the decimal
representation produced by this method for a finite nonzero
argument f. Then f must be the float
value nearest to x; or, if two float
values are
equally close to x, then f must be one of
them and the least significant bit of the significand of
f must be 0
.
To create localized string representations of a floatingpoint
value, use subclasses of NumberFormat
.
Parameters  

f 
float : the float to be converted. 
Returns  

String 
a string representation of the argument. 
valueOf
Float valueOf (String s)
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 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:
where Sign, FloatingPointLiteral, HexNumeral, HexDigits, SignedInteger and FloatTypeSuffix are as defined in the lexical structure sections of The Java™ Language Specification, except that underscores are not accepted between digits. If
 FloatValue:
 Sign_{opt}
NaN
 Sign_{opt}
Infinity
 Sign_{opt} FloatingPointLiteral
 Sign_{opt} HexFloatingPointLiteral
 SignedInteger
 HexFloatingPointLiteral:
 HexSignificand BinaryExponent FloatTypeSuffix_{opt}
 HexSignificand:
 HexNumeral
 HexNumeral
.
0x
HexDigits_{opt}.
HexDigits0X
HexDigits_{opt}.
HexDigits
 BinaryExponent:
 BinaryExponentIndicator SignedInteger
 BinaryExponentIndicator:
p
P
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 roundtonearest rule of IEEE 754 floatingpoint
arithmetic, which includes preserving the sign of a zero
value.
Note that the roundtonearest rule also implies overflow and
underflow behaviour; if the exact value of s
is large
enough in magnitude (greater than or equal to (MAX_VALUE
+ ulp(MAX_VALUE)
/2),
rounding to float
will result in an infinity and if the
exact value of s
is small enough in magnitude (less
than or equal to MIN_VALUE
/2), rounding to float will
result in a zero.
Finally, after rounding a Float
object representing
this float
value is returned.
To interpret localized string representations of a
floatingpoint value, use subclasses of NumberFormat
.
Note that trailing format specifiers, specifiers that
determine the type of a floatingpoint 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 floatingpoint type. In general, the
twostep 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.
Parameters  

s 
String : the string to be parsed. 
Returns  

Float 
a Float object holding the value
represented by the String argument. 
Throws  

NumberFormatException 
if the string does not contain a parsable number. 
valueOf
Float valueOf (float f)
Returns a Float
instance representing the specified
float
value.
If a new Float
instance is not required, this method
should generally be used in preference to the constructor
Float(float)
, as this method is likely to yield
significantly better space and time performance by caching
frequently requested values.
Parameters  

f 
float : a float value. 
Returns  

Float 
a Float instance representing f . 