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
.
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 
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 


From class java.lang.Number


From class java.lang.Object


From interface java.lang.Comparable

int BYTES
The number of bytes used to represent a float
value.
Constant Value: 4 (0x00000004)
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)
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
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)
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
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
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
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
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
int SIZE
The number of bits used to represent a float
value.
Constant Value: 32 (0x00000020)
Class<Float> TYPE
The Class
instance representing the primitive type 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 (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 (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:
byte byteValue ()
Returns the value of this Float
as a byte
(by casting to a byte
).
Returns  

byte 
the float value represented by this object converted to type byte 
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 . 
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 other float
values (including Float.POSITIVE_INFINITY
). 0.0f
is considered by this method to be greater than 0.0f
. 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:
double doubleValue ()
Returns the double
value of this Float
object.
Returns  

double 
the float value represented by this object is converted to type double and the result of the conversion is returned. 
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:
f1
and f2
both represent Float.NaN
, then the equals
method returns true
, even though Float.NaN==Float.NaN
has the value false
. f1
represents +0.0f
while f2
represents 0.0f
, or vice versa, the equal
test has the value false
, even though 0.0f==0.0f
has the value true
. Parameters  

obj 
Object : the object to be compared 
Returns  

boolean 
true if the objects are the same; false otherwise. 
See also:
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. 
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. 
float floatValue ()
Returns the float
value of this Float
object.
Returns  

float 
the float value represented by this object 
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. 
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. 
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. 
int intValue ()
Returns the value of this Float
as an int
(by casting to type int
).
Returns  

int 
the float value represented by this object converted to type int 
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. 
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. 
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. 
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. 
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. 
long longValue ()
Returns value of this Float
as a long
(by casting to type long
).
Returns  

long 
the float value represented by this object converted to type long 
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:
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:
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:
short shortValue ()
Returns the value of this Float
as a short
(by casting to a short
).
Returns  

short 
the float value represented by this object converted to type short 
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:
String toHexString (float f)
Returns a hexadecimal string representation of the float
argument. All characters mentioned below are ASCII characters.
NaN
". 
' ('\u002D'
); if the sign is positive, no sign character appears in the result. As for the magnitude m:
"Infinity"
; thus, positive infinity produces the result "Infinity"
and negative infinity produces the result "Infinity"
. "0x0.0p0"
; thus, negative zero produces the result "0x0.0p0"
and positive zero produces the result "0x0.0p0"
. 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 to Integer.toString
on the exponent value. 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. 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. 
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:
String toString (float f)
Returns a string representation of the float
argument. All characters mentioned below are ASCII characters.
NaN
". 
' ('\u002D'
); if the sign is positive, no sign character appears in the result. As for the magnitude m:
"Infinity"
; thus, positive infinity produces the result "Infinity"
and negative infinity produces the result "Infinity"
. "0.0"
; thus, negative zero produces the result "0.0"
and positive zero produces the result "0.0"
. .
' ('\u002E'
), followed by one or more decimal digits representing the fractional part of m. .
' ('\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 method toString(int)
. 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. 
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. 
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 . 