Class Float
 java.lang.Object

 java.lang.Number

 java.lang.Float
 All Implemented Interfaces:

Serializable
,Comparable<Float>
public final class Float extends Number implements Comparable<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
.
 Since:
 1.0
 See Also:
 Serialized Form
Field Summary
Modifier and Type  Field  Description 

static int  BYTES  The number of bytes used to represent a 
static int  MAX_EXPONENT  Maximum exponent a finite 
static float  MAX_VALUE  A constant holding the largest positive finite value of type 
static int  MIN_EXPONENT  Minimum exponent a normalized 
static float  MIN_NORMAL  A constant holding the smallest positive normal value of type 
static float  MIN_VALUE  A constant holding the smallest positive nonzero value of type 
static float  NaN  A constant holding a NotaNumber (NaN) value of type 
static float  NEGATIVE_INFINITY  A constant holding the negative infinity of type 
static float  POSITIVE_INFINITY  A constant holding the positive infinity of type 
static int  SIZE  The number of bits used to represent a 
static Class<Float>  TYPE  The 
Constructor Summary
Constructor  Description 

Float(double value)  Deprecated. It is rarely appropriate to use this constructor. 
Float(float value)  Deprecated. It is rarely appropriate to use this constructor. 
Float(String s)  Deprecated. It is rarely appropriate to use this constructor. 
Method Summary
Modifier and Type  Method  Description 

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 
boolean  isNaN()  Returns 
static boolean  isNaN(float v)  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(float f)  Returns a 
static Float  valueOf(String s)  Returns a 
Methods declared in class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
Field Detail
POSITIVE_INFINITY
public static final float POSITIVE_INFINITY
A constant holding the positive infinity of type float
. It is equal to the value returned by Float.intBitsToFloat(0x7f800000)
.
 See Also:
 Constant Field Values
NEGATIVE_INFINITY
public static final float NEGATIVE_INFINITY
A constant holding the negative infinity of type float
. It is equal to the value returned by Float.intBitsToFloat(0xff800000)
.
 See Also:
 Constant Field Values
NaN
public static final float NaN
A constant holding a NotaNumber (NaN) value of type float
. It is equivalent to the value returned by Float.intBitsToFloat(0x7fc00000)
.
 See Also:
 Constant Field Values
MAX_VALUE
public static final 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)
.
 See Also:
 Constant Field Values
MIN_NORMAL
public static final 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)
.
 Since:
 1.6
 See Also:
 Constant Field Values
MIN_VALUE
public static final 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)
.
 See Also:
 Constant Field Values
MAX_EXPONENT
public static final int MAX_EXPONENT
Maximum exponent a finite float
variable may have. It is equal to the value returned by
Math.getExponent(Float.MAX_VALUE)
.
 Since:
 1.6
 See Also:
 Constant Field Values
MIN_EXPONENT
public static final int MIN_EXPONENT
Minimum exponent a normalized float
variable may have. It is equal to the value returned by
Math.getExponent(Float.MIN_NORMAL)
.
 Since:
 1.6
 See Also:
 Constant Field Values
SIZE
public static final int SIZE
The number of bits used to represent a float
value.
 Since:
 1.5
 See Also:
 Constant Field Values
BYTES
public static final int BYTES
The number of bytes used to represent a float
value.
 Since:
 1.8
 See Also:
 Constant Field Values
TYPE
public static final Class<Float> TYPE
The Class
instance representing the primitive type float
.
 Since:
 1.1
Constructor Detail
Float
@Deprecated(since="9") public Float(float value)
valueOf(float)
is generally a better choice, as it is likely to yield significantly better space and time performance.Constructs a newly allocated Float
object that represents the primitive float
argument.
 Parameters:

value
 the value to be represented by theFloat
.
Float
@Deprecated(since="9") public Float(double value)
valueOf(float)
method as follows: Float.valueOf((float)value)
.Constructs a newly allocated Float
object that represents the argument converted to type float
.
 Parameters:

value
 the value to be represented by theFloat
.
Float
@Deprecated(since="9") public Float(String s) throws NumberFormatException
parseFloat(String)
to convert a string to a float
primitive, or use valueOf(String)
to convert a string to a Float
object.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
 a string to be converted to aFloat
.  Throws:

NumberFormatException
 if the string does not contain a parsable number.
Method Detail
toString
public static 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 methodInteger.toString(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
 the float to be converted.  Returns:
 a string representation of the argument.
toHexString
public static 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
 thefloat
to be converted.  Returns:
 a hex string representation of the argument.
 Since:
 1.5
valueOf
public static Float valueOf(String s) throws NumberFormatException
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:
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
 the string to be parsed.  Returns:
 a
Float
object holding the value represented by theString
argument.  Throws:

NumberFormatException
 if the string does not contain a parsable number.
valueOf
public static 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
 a float value.  Returns:
 a
Float
instance representingf
.  Since:
 1.5
parseFloat
public static float parseFloat(String s) throws NumberFormatException
Returns a new float
initialized to the value represented by the specified String
, as performed by the valueOf
method of class Float
.
 Parameters:

s
 the string to be parsed.  Returns:
 the
float
value represented by the string argument.  Throws:

NullPointerException
 if the string is null 
NumberFormatException
 if the string does not contain a parsablefloat
.  Since:
 1.2
 See Also:
valueOf(String)
isNaN
public static boolean isNaN(float v)
Returns true
if the specified number is a NotaNumber (NaN) value, false
otherwise.
 Parameters:

v
 the value to be tested.  Returns:

true
if the argument is NaN;false
otherwise.
isInfinite
public static boolean isInfinite(float v)
Returns true
if the specified number is infinitely large in magnitude, false
otherwise.
 Parameters:

v
 the value to be tested.  Returns:

true
if the argument is positive infinity or negative infinity;false
otherwise.
isFinite
public static boolean isFinite(float f)
Returns true
if the argument is a finite floatingpoint value; returns false
otherwise (for NaN and infinity arguments).
 Parameters:

f
 thefloat
value to be tested  Returns:

true
if the argument is a finite floatingpoint value,false
otherwise.  Since:
 1.8
isNaN
public boolean isNaN()
Returns true
if this Float
value is a NotaNumber (NaN), false
otherwise.
 Returns:

true
if the value represented by this object is NaN;false
otherwise.
isInfinite
public boolean isInfinite()
Returns true
if this Float
value is infinitely large in magnitude, false
otherwise.
 Returns:

true
if the value represented by this object is positive infinity or negative infinity;false
otherwise.
toString
public 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.
 Overrides:

toString
in classObject
 Returns:
 a
String
representation of this object.  See Also:
toString(float)
byteValue
public byte byteValue()
Returns the value of this Float
as a byte
after a narrowing primitive conversion.
 Overrides:

byteValue
in classNumber
 Returns:
 the
float
value represented by this object converted to typebyte
shortValue
public short shortValue()
Returns the value of this Float
as a short
after a narrowing primitive conversion.
 Overrides:

shortValue
in classNumber
 Returns:
 the
float
value represented by this object converted to typeshort
 Since:
 1.1
intValue
public int intValue()
Returns the value of this Float
as an int
after a narrowing primitive conversion.
 Specified by:

intValue
in classNumber
 Returns:
 the
float
value represented by this object converted to typeint
longValue
public long longValue()
Returns value of this Float
as a long
after a narrowing primitive conversion.
 Specified by:

longValue
in classNumber
 Returns:
 the
float
value represented by this object converted to typelong
floatValue
public float floatValue()
Returns the float
value of this Float
object.
 Specified by:

floatValue
in classNumber
 Returns:
 the
float
value represented by this object
doubleValue
public double doubleValue()
Returns the value of this Float
as a double
after a widening primitive conversion.
 Specified by:

doubleValue
in classNumber
 Returns:
 the
float
value represented by this object converted to typedouble
hashCode
public 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.
 Overrides:

hashCode
in classObject
 Returns:
 a hash code value for this object.
 See Also:

Object.equals(java.lang.Object)
,System.identityHashCode(java.lang.Object)
hashCode
public static int hashCode(float value)
Returns a hash code for a float
value; compatible with Float.hashCode()
.
 Parameters:

value
 the value to hash  Returns:
 a hash code value for a
float
value.  Since:
 1.8
equals
public 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
.
 Overrides:

equals
in classObject
 Parameters:

obj
 the object to be compared  Returns:

true
if the objects are the same;false
otherwise.  See Also:
floatToIntBits(float)
floatToIntBits
public static 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
 a floatingpoint number.  Returns:
 the bits that represent the floatingpoint number.
floatToRawIntBits
public 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.
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
 a floatingpoint number.  Returns:
 the bits that represent the floatingpoint number.
 Since:
 1.3
intBitsToFloat
public static 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:
int s = ((bits >> 31) == 0) ? 1 : 1; int e = ((bits >> 23) & 0xff); int m = (e == 0) ? (bits & 0x7fffff) << 1 : (bits & 0x7fffff)  0x800000;Then the floatingpoint result equals the value of the mathematical expression s·m·2^{e150}.
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
 an integer.  Returns:
 the
float
floatingpoint value with the same bit pattern.
compareTo
public 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.  Specified by:

compareTo
in interfaceComparable<Float>
 Parameters:

anotherFloat
 theFloat
to be compared.  Returns:
 the value
0
ifanotherFloat
is numerically equal to thisFloat
; a value less than0
if thisFloat
is numerically less thananotherFloat
; and a value greater than0
if thisFloat
is numerically greater thananotherFloat
.  Since:
 1.2
 See Also:
Comparable.compareTo(Object)
compare
public static 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
 the firstfloat
to compare. 
f2
 the secondfloat
to compare.  Returns:
 the value
0
iff1
is numerically equal tof2
; a value less than0
iff1
is numerically less thanf2
; and a value greater than0
iff1
is numerically greater thanf2
.  Since:
 1.4
sum
public static float sum(float a, float b)
Adds two float
values together as per the + operator.
 Parameters:

a
 the first operand 
b
 the second operand  Returns:
 the sum of
a
andb
 Since:
 1.8
 See Also:
BinaryOperator
max
public static float max(float a, float b)
Returns the greater of two float
values as if by calling Math.max
.
 Parameters:

a
 the first operand 
b
 the second operand  Returns:
 the greater of
a
andb
 Since:
 1.8
 See Also:
BinaryOperator
min
public static float min(float a, float b)
Returns the smaller of two float
values as if by calling Math.min
.
 Parameters:

a
 the first operand 
b
 the second operand  Returns:
 the smaller of
a
andb
 Since:
 1.8
 See Also:
BinaryOperator