Top Description Fields Constructors Methods
java.lang

public final Class Float

extends Number
implements Comparable<Float>, Constable, ConstantDesc
Class Inheritance
All Implemented Interfaces
java.lang.constant.ConstantDesc, java.lang.constant.Constable, java.lang.Comparable
Annotations
@ValueBased
Imports
java.lang.invoke.MethodHandles, java.lang.constant.Constable, .ConstantDesc, java.util.Optional, jdk.internal.math.FloatConsts, .FloatingDecimal, .FloatToDecimal, jdk.internal.vm.annotation.IntrinsicCandidate

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.

This is a value-based class; programmers should treat instances that are equal as interchangeable and should not use instances for synchronization, or unpredictable behavior may occur. For example, in a future release, synchronization may fail.

Floating-point Equality, Equivalence, and Comparison

The class java.lang.Double has a discussion of equality, equivalence, and comparison of floating-point values that is equally applicable to float values.

Decimal ↔ Binary Conversion Issues

The discussion of binary to decimal conversion issues in java.lang.Double is also applicable to float values.
Authors
Lee Boynton, Arthur van Hoff, Joseph D. Darcy
Since
1.0
See Also
IEEE Standard for Floating-Point Arithmetic

Field Summary

Modifier and TypeField and Description
public static final int
BYTES

The number of bytes used to represent a float value.

public static final int
MAX_EXPONENT

Maximum exponent a finite float variable may have.

public static final float
MAX_VALUE

A constant holding the largest positive finite value of type float, (2-2-23)·2127.

public static final int
MIN_EXPONENT

Minimum exponent a normalized float variable may have.

public static final float
MIN_NORMAL

A constant holding the smallest positive normal value of type float, 2-126.

public static final float
MIN_VALUE

A constant holding the smallest positive nonzero value of type float, 2-149.

public static final float
NaN

A constant holding a Not-a-Number (NaN) value of type float.

public static final float
NEGATIVE_INFINITY

A constant holding the negative infinity of type float.

public static final float
POSITIVE_INFINITY

A constant holding the positive infinity of type float.

public static final int
PRECISION

The number of bits in the significand of a float value.

private static final long
serialVersionUID

Hides java.lang.Number.serialVersionUID.

use serialVersionUID from JDK 1.0.2 for interoperability
public static final int
SIZE

The number of bits used to represent a float value.

public static final Class<Float>
TYPE

The Class instance representing the primitive type float.

private final float
value

The value of the Float.

Constructor Summary

AccessConstructor and Description
public
Float(float
the value to be represented by the Float.
value
)
Deprecated for removal since 9. It is rarely appropriate to use this constructor.

Constructs a newly allocated Float object that represents the primitive float argument.

public
Float(double
the value to be represented by the Float.
value
)
Deprecated for removal since 9. It is rarely appropriate to use this constructor.

Constructs a newly allocated Float object that represents the argument converted to type float.

public
Float(String
a string to be converted to a Float.
s
)
Deprecated for removal since 9. It is rarely appropriate to use this constructor.

Constructs a newly allocated Float object that represents the floating-point value of type float represented by the string.

Method Summary

Modifier and TypeMethod and Description
public byte

Returns:

the float value represented by this object converted to type byte
byteValue
()

Overrides java.lang.Number.byteValue.

Returns the value of this Float as a byte after a narrowing primitive conversion.

public static int

Returns:

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.
compare
(float
the first float to compare.
f1
,
float
the second float to compare.
f2
)

Compares the two specified float values.

public int

Returns:

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.
compareTo
(Float
the Float to be compared.
anotherFloat
)

Implements java.lang.Comparable.compareTo.

Compares two Float objects numerically.

public Optional<Float>

Returns:

an Optional describing the Float instance
describeConstable
()

Implements java.lang.constant.Constable.describeConstable.

Returns an Optional containing the nominal descriptor for this instance, which is the instance itself.

public double

Returns:

the float value represented by this object converted to type double
doubleValue
()

Implements abstract java.lang.Number.doubleValue.

Returns the value of this Float as a double after a widening primitive conversion.

public boolean

Returns:

true if the objects are the same; false otherwise.
equals
(Object
the object to be compared
obj
)

Overrides java.lang.Object.equals.

Compares this object against the specified object.

public static float

Returns:

the float value closest to the numerical value of the argument, a floating-point binary16 value encoded in a short
float16ToFloat
(short
the binary16 value to convert to float
floatBinary16
)

Returns the float value closest to the numerical value of the argument, a floating-point binary16 value encoded in a short.

public static short

Returns:

the floating-point binary16 value, encoded in a short, closest in value to the argument
floatToFloat16
(float
the float value to convert to binary16
f
)

Returns the floating-point binary16 value, encoded in a short, closest in value to the argument.

public static int

Returns:

the bits that represent the floating-point number.
floatToIntBits
(float
a floating-point number.
value
)

Returns a representation of the specified floating-point value according to the IEEE 754 floating-point "single format" bit layout.

public static native int

Returns:

the bits that represent the floating-point number.
floatToRawIntBits
(float
a floating-point number.
value
)

Returns a representation of the specified floating-point value according to the IEEE 754 floating-point "single format" bit layout, preserving Not-a-Number (NaN) values.

public float

Returns:

the float value represented by this object
floatValue
()

Implements abstract java.lang.Number.floatValue.

Returns the float value of this Float object.

public int

Returns:

a hash code value for this object.
hashCode
()

Overrides java.lang.Object.hashCode.

Returns a hash code for this Float object.

public static int

Returns:

a hash code value for a float value.
hashCode
(float
the value to hash
value
)

Returns a hash code for a float value; compatible with Float.hashCode().

public static native float

Returns:

the float floating-point value with the same bit pattern.
intBitsToFloat
(int
an integer.
bits
)

Returns the float value corresponding to a given bit representation.

public int

Returns:

the float value represented by this object converted to type int
intValue
()

Implements abstract java.lang.Number.intValue.

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

public static boolean

Returns:

true if the argument is a finite floating-point value, false otherwise.
isFinite
(float
the float value to be tested
f
)

Returns true if the argument is a finite floating-point value; returns false otherwise (for NaN and infinity arguments).

public static boolean

Returns:

true if the argument is positive infinity or negative infinity; false otherwise.
isInfinite
(float
the value to be tested.
v
)

Returns true if the specified number is infinitely large in magnitude, false otherwise.

public boolean

Returns:

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

Returns true if this Float value is infinitely large in magnitude, false otherwise.

public static boolean

Returns:

true if the argument is NaN; false otherwise.
isNaN
(float
the value to be tested.
v
)

Returns true if the specified number is a Not-a-Number (NaN) value, false otherwise.

public boolean

Returns:

true if the value represented by this object is NaN; false otherwise.
isNaN
()

Returns true if this Float value is a Not-a-Number (NaN), false otherwise.

public long

Returns:

the float value represented by this object converted to type long
longValue
()

Implements abstract java.lang.Number.longValue.

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

public static float

Returns:

the greater of a and b
max
(float
the first operand
a
,
float
the second operand
b
)

Returns the greater of two float values as if by calling Math.max.

public static float

Returns:

the smaller of a and b
min
(float
the first operand
a
,
float
the second operand
b
)

Returns the smaller of two float values as if by calling Math.min.

public static float

Returns:

the float value represented by the string argument.
parseFloat
(String
the string to be parsed.
s
)

Returns a new float initialized to the value represented by the specified String, as performed by the valueOf method of class Float.

public Float

Returns:

the Float instance
resolveConstantDesc
(MethodHandles.Lookup
ignored
lookup
)

Implements java.lang.constant.ConstantDesc.resolveConstantDesc.

Resolves this instance as a ConstantDesc, the result of which is the instance itself.

public short

Returns:

the float value represented by this object converted to type short
shortValue
()

Overrides java.lang.Number.shortValue.

Returns the value of this Float as a short after a narrowing primitive conversion.

public static float

Returns:

the sum of a and b
sum
(float
the first operand
a
,
float
the second operand
b
)

Adds two float values together as per the + operator.

public static String

Returns:

a hex string representation of the argument.
toHexString
(float
the float to be converted.
f
)

Returns a hexadecimal string representation of the float argument.

public static String

Returns:

a string representation of the argument.
toString
(float
the float to be converted.
f
)

Returns a string representation of the float argument.

public String

Returns:

a String representation of this object.
toString
()

Overrides java.lang.Object.toString.

Returns a string representation of this Float object.

public static Float

Returns:

a Float object holding the value represented by the String argument.
valueOf
(String
the string to be parsed.
s
)

Returns a Float object holding the float value represented by the argument string s.

public static Float

Returns:

a Float instance representing f.
valueOf
(float
a float value.
f
)

Returns a Float instance representing the specified float value.

Field Detail

BYTESback to summary
public static final int BYTES

The number of bytes used to represent a float value.

Since
1.8
MAX_EXPONENTback to summary
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
MAX_VALUEback to summary
public static final float MAX_VALUE

A constant holding the largest positive finite value of type float, (2-2-23)·2127. It is equal to the hexadecimal floating-point literal 0x1.fffffeP+127f and also equal to Float.intBitsToFloat(0x7f7fffff).

MIN_EXPONENTback to summary
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
MIN_NORMALback to summary
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 floating-point literal 0x1.0p-126f and also equal to Float.intBitsToFloat(0x00800000).

Since
1.6
MIN_VALUEback to summary
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 floating-point literal 0x0.000002P-126f and also equal to Float.intBitsToFloat(0x1).

NaNback to summary
public static final float NaN

A constant holding a Not-a-Number (NaN) value of type float. It is equivalent to the value returned by Float.intBitsToFloat(0x7fc00000).

NEGATIVE_INFINITYback to summary
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).

POSITIVE_INFINITYback to summary
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).

PRECISIONback to summary
public static final int PRECISION

The number of bits in the significand of a float value. This is the parameter N in section 4.2.3 of The Java Language Specification.

Since
19
serialVersionUIDback to summary
private static final long serialVersionUID

Hides java.lang.Number.serialVersionUID.

use serialVersionUID from JDK 1.0.2 for interoperability

Annotations
@Serial
SIZEback to summary
public static final int SIZE

The number of bits used to represent a float value.

Since
1.5
TYPEback to summary
public static final Class<Float> TYPE

The Class instance representing the primitive type float.

Annotations
@SuppressWarnings:unchecked
Since
1.1
valueback to summary
private final float value

The value of the Float.

Constructor Detail

Floatback to summary
public Float(float value)

Deprecated

for removal since 9.

It is rarely appropriate to use this constructor. The static factory 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:float

the value to be represented by the Float.

Annotations
@Deprecated
since:9
forRemoval:true
Floatback to summary
public Float(double value)

Deprecated

for removal since 9.

It is rarely appropriate to use this constructor. Instead, use the static factory method 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:double

the value to be represented by the Float.

Annotations
@Deprecated
since:9
forRemoval:true
Floatback to summary
public Float(String s) throws NumberFormatException

Deprecated

for removal since 9.

It is rarely appropriate to use this constructor. Use 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 floating-point 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.

Annotations
@Deprecated
since:9
forRemoval:true
Exceptions
NumberFormatException:
if the string does not contain a parsable number.

Method Detail

byteValueback to summary
public byte byteValue()

Overrides java.lang.Number.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

Java Language Specification
5.1.3 Narrowing Primitive Conversion
compareback to summary
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:

   Float.valueOf(f1).compareTo(Float.valueOf(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.

Since
1.4
compareToback to summary
public int compareTo(Float anotherFloat)

Implements java.lang.Comparable.compareTo.

Compares two Float objects numerically. This method imposes a total order on Float objects with two differences compared to the incomplete order defined by the Java language numerical comparison operators (<, <=, ==, >=, >) on float values.

  • A NaN is unordered with respect to other values and unequal to itself under the comparison operators. This method chooses to define Float.NaN to be equal to itself and greater than all other double values (including Float.POSITIVE_INFINITY).
  • Positive zero and negative zero compare equal numerically, but are distinct and distinguishable values. This method chooses to define positive zero (+0.0f), to be greater than negative zero (-0.0f).
This ensures that the natural ordering of Float objects imposed by this method is consistent with equals; see this discussion for details of floating-point comparison and ordering.
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.

Since
1.2
Java Language Specification
15.20.1 Numerical Comparison Operators <, <=, >, and >=
describeConstableback to summary
public Optional<Float> describeConstable()

Implements java.lang.constant.Constable.describeConstable.

Returns an Optional containing the nominal descriptor for this instance, which is the instance itself.

Returns:Optional<Float>

an Optional describing the Float instance

Annotations
@Override
Since
12
doubleValueback to summary
public double doubleValue()

Implements abstract java.lang.Number.doubleValue.

Returns the value of this Float as a double after a widening primitive conversion.

API Note

This method corresponds to the convertFormat operation defined in IEEE 754.

Returns:double

the float value represented by this object converted to type double

Java Language Specification
5.1.2 Widening Primitive Conversion
equalsback to summary
public boolean equals(Object obj)

Overrides java.lang.Object.equals.

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.

API Note

This method is defined in terms of floatToIntBits(float) rather than the == operator on float values since the == operator does not define an equivalence relation and to satisfy the equals contract an equivalence relation must be implemented; see this discussion for details of floating-point equality and equivalence.

Parameters
obj:Object

the object to be compared

Returns:boolean

true if the objects are the same; false otherwise.

Java Language Specification
15.21.1 Numerical Equality Operators == and !=
See Also
java.lang.Float#floatToIntBits(float)
float16ToFloatback to summary
public static float float16ToFloat(short floatBinary16)

Returns the float value closest to the numerical value of the argument, a floating-point binary16 value encoded in a short. The conversion is exact; all binary16 values can be exactly represented in float. Special cases:

  • If the argument is zero, the result is a zero with the same sign as the argument.
  • If the argument is infinite, the result is an infinity with the same sign as the argument.
  • If the argument is a NaN, the result is a NaN.

IEEE 754 binary16 format

The IEEE 754 standard defines binary16 as a 16-bit format, along with the 32-bit binary32 format (corresponding to the float type) and the 64-bit binary64 format (corresponding to the double type). The binary16 format is similar to the other IEEE 754 formats, except smaller, having all the usual IEEE 754 values such as NaN, signed infinities, signed zeros, and subnormals. The parameters (JLS 4.2.3) for the binary16 format are N = 11 precision bits, K = 5 exponent bits, Emax = 15, and Emin = -14.

API Note

This method corresponds to the convertFormat operation defined in IEEE 754 from the binary16 format to the binary32 format. The operation of this method is analogous to a primitive widening conversion (JLS 5.1.2).

Parameters
floatBinary16:short

the binary16 value to convert to float

Returns:float

the float value closest to the numerical value of the argument, a floating-point binary16 value encoded in a short

Annotations
@IntrinsicCandidate
Since
20
floatToFloat16back to summary
public static short floatToFloat16(float f)

Returns the floating-point binary16 value, encoded in a short, closest in value to the argument. The conversion is computed under the round to nearest even rounding mode. Special cases:

  • If the argument is zero, the result is a zero with the same sign as the argument.
  • If the argument is infinite, the result is an infinity with the same sign as the argument.
  • If the argument is a NaN, the result is a NaN.
The binary16 format is discussed in more detail in the float16ToFloat method.

API Note

This method corresponds to the convertFormat operation defined in IEEE 754 from the binary32 format to the binary16 format. The operation of this method is analogous to a primitive narrowing conversion (JLS 5.1.3).

Parameters
f:float

the float value to convert to binary16

Returns:short

the floating-point binary16 value, encoded in a short, closest in value to the argument

Annotations
@IntrinsicCandidate
Since
20
floatToIntBitsback to summary
public static int floatToIntBits(float value)

Returns a representation of the specified floating-point value according to the IEEE 754 floating-point "single format" bit layout.

Bit 31 (the bit that is selected by the mask 0x80000000) represents the sign of the floating-point number. Bits 30-23 (the bits that are selected by the mask 0x7f800000) represent the exponent. Bits 22-0 (the bits that are selected by the mask 0x007fffff) represent the significand (sometimes called the mantissa) of the floating-point 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 floating-point value the same as the argument to floatToIntBits (except all NaN values are collapsed to a single "canonical" NaN value).

Parameters
value:float

a floating-point number.

Returns:int

the bits that represent the floating-point number.

Annotations
@IntrinsicCandidate
floatToRawIntBitsback to summary
public static native int floatToRawIntBits(float value)

Returns a representation of the specified floating-point value according to the IEEE 754 floating-point "single format" bit layout, preserving Not-a-Number (NaN) values.

Bit 31 (the bit that is selected by the mask 0x80000000) represents the sign of the floating-point number. Bits 30-23 (the bits that are selected by the mask 0x7f800000) represent the exponent. Bits 22-0 (the bits that are selected by the mask 0x007fffff) represent the significand (sometimes called the mantissa) of the floating-point 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 floating-point value the same as the argument to floatToRawIntBits.

Parameters
value:float

a floating-point number.

Returns:int

the bits that represent the floating-point number.

Annotations
@IntrinsicCandidate
Since
1.3
floatValueback to summary
public float floatValue()

Implements abstract java.lang.Number.floatValue.

Returns the float value of this Float object.

Returns:float

the float value represented by this object

Annotations
@IntrinsicCandidate
hashCodeback to summary
public int hashCode()

Overrides java.lang.Object.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.

Annotations
@Override
hashCodeback to summary
public static 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.

Since
1.8
intBitsToFloatback to summary
public static native float intBitsToFloat(int bits)

Returns the float value corresponding to a given bit representation. The argument is considered to be a representation of a floating-point value according to the IEEE 754 floating-point "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 floating-point 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;
int s = ((bits >> 31) == 0) ? 1 : -1;
int e = ((bits >> 23) & 0xff);
int m = (e == 0) ?
                (bits & 0x7fffff) << 1 :
                (bits & 0x7fffff) | 0x800000;
Then the floating-point result equals the value of the mathematical expression s·m·2e-150.

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 floating-point value with the same bit pattern.

Annotations
@IntrinsicCandidate
intValueback to summary
public int intValue()

Implements abstract java.lang.Number.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

Java Language Specification
5.1.3 Narrowing Primitive Conversion
isFiniteback to summary
public static boolean isFinite(float f)

Returns true if the argument is a finite floating-point value; returns false otherwise (for NaN and infinity arguments).

API Note

This method corresponds to the isFinite operation defined in IEEE 754.

Parameters
f:float

the float value to be tested

Returns:boolean

true if the argument is a finite floating-point value, false otherwise.

Annotations
@IntrinsicCandidate
Since
1.8
isInfiniteback to summary
public static boolean isInfinite(float v)

Returns true if the specified number is infinitely large in magnitude, false otherwise.

API Note

This method corresponds to the isInfinite operation defined in IEEE 754.

Parameters
v:float

the value to be tested.

Returns:boolean

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

Annotations
@IntrinsicCandidate
isInfiniteback to summary
public 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.

isNaNback to summary
public static boolean isNaN(float v)

Returns true if the specified number is a Not-a-Number (NaN) value, false otherwise.

API Note

This method corresponds to the isNaN operation defined in IEEE 754.

Parameters
v:float

the value to be tested.

Returns:boolean

true if the argument is NaN; false otherwise.

isNaNback to summary
public boolean isNaN()

Returns true if this Float value is a Not-a-Number (NaN), false otherwise.

Returns:boolean

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

longValueback to summary
public long longValue()

Implements abstract java.lang.Number.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

Java Language Specification
5.1.3 Narrowing Primitive Conversion
maxback to summary
public static float max(float a, float b)

Returns the greater of two float values as if by calling Math.max.

API Note

This method corresponds to the maximum operation defined in IEEE 754.

Parameters
a:float

the first operand

b:float

the second operand

Returns:float

the greater of a and b

Since
1.8
See Also
java.util.function.BinaryOperator
minback to summary
public static float min(float a, float b)

Returns the smaller of two float values as if by calling Math.min.

API Note

This method corresponds to the minimum operation defined in IEEE 754.

Parameters
a:float

the first operand

b:float

the second operand

Returns:float

the smaller of a and b

Since
1.8
See Also
java.util.function.BinaryOperator
parseFloatback to summary
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:String

the string to be parsed.

Returns:float

the float value represented by the string argument.

Exceptions
NumberFormatException:
if the string does not contain a parsable float.
NullPointerException:
if the string is null
Since
1.2
See Also
java.lang.Float#valueOf(String), Decimal ↔ Binary Conversion Issues
resolveConstantDescback to summary
public Float resolveConstantDesc(MethodHandles.Lookup lookup)

Implements java.lang.constant.ConstantDesc.resolveConstantDesc.

Resolves this instance as a ConstantDesc, the result of which is the instance itself.

Parameters
lookup:MethodHandles.Lookup

ignored

Returns:Float

the Float instance

Annotations
@Override
Since
12
shortValueback to summary
public short shortValue()

Overrides java.lang.Number.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

Since
1.1
Java Language Specification
5.1.3 Narrowing Primitive Conversion
sumback to summary
public static float sum(float a, float b)

Adds two float values together as per the + operator.

API Note

This method corresponds to the addition operation defined in IEEE 754.

Parameters
a:float

the first operand

b:float

the second operand

Returns:float

the sum of a and b

Since
1.8
Java Language Specification
4.2.4 Floating-Point Operations
See Also
java.util.function.BinaryOperator
toHexStringback to summary
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 to Integer.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 "p-126". Note that there must be at least one nonzero digit in a subnormal significand.
Examples
Floating-point ValueHexadecimal String
1.0 0x1.0p0
-1.0 -0x1.0p0
2.0 0x1.0p1
3.0 0x1.8p1
0.5 0x1.0p-1
0.25 0x1.0p-2
Float.MAX_VALUE 0x1.fffffep127
Minimum Normal Value 0x1.0p-126
Maximum Subnormal Value 0x0.fffffep-126
Float.MIN_VALUE 0x0.000002p-126
Parameters
f:float

the float to be converted.

Returns:String

a hex string representation of the argument.

Author
Joseph D. Darcy
Since
1.5
toStringback to summary
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".
    • Otherwise m is positive and finite. It is converted to a string in two stages:
      • Selection of a decimal: A well-defined decimal dm is selected to represent m. This decimal is (almost always) the shortest one that rounds to m according to the round to nearest rounding policy of IEEE 754 floating-point arithmetic.
      • Formatting as a string: The decimal dm is formatted as a string, either in plain or in computerized scientific notation, depending on its value.

A decimal is a number of the form s×10i for some (unique) integers s > 0 and i such that s is not a multiple of 10. These integers are the significand and the exponent, respectively, of the decimal. The length of the decimal is the (unique) positive integer n meeting 10n-1s < 10n.

The decimal dm for a finite positive m is defined as follows:

  • Let R be the set of all decimals that round to m according to the usual round to nearest rounding policy of IEEE 754 floating-point arithmetic.
  • Let p be the minimal length over all decimals in R.
  • When p ≥ 2, let T be the set of all decimals in R with length p. Otherwise, let T be the set of all decimals in R with length 1 or 2.
  • Define dm as the decimal in T that is closest to m. Or if there are two such decimals in T, select the one with the even significand.

The (uniquely) selected decimal dm is then formatted. Let s, i and n be the significand, exponent and length of dm, respectively. Further, let e = n + i - 1 and let s1sn be the usual decimal expansion of s. Note that s1 ≠ 0 and sn ≠ 0. Below, the decimal point '.' is '\u002E' and the exponent indicator 'E' is '\u0045'.

  • Case -3 ≤ e < 0: dm is formatted as 0.00s1sn, where there are exactly -(n + i) zeroes between the decimal point and s1. For example, 123 × 10-4 is formatted as 0.0123.
  • Case 0 ≤ e < 7:
    • Subcase i ≥ 0: dm is formatted as s1sn00.0, where there are exactly i zeroes between sn and the decimal point. For example, 123 × 102 is formatted as 12300.0.
    • Subcase i < 0: dm is formatted as s1sn+i.sn+i+1sn, where there are exactly -i digits to the right of the decimal point. For example, 123 × 10-1 is formatted as 12.3.
  • Case e < -3 or e ≥ 7: computerized scientific notation is used to format dm. Here e is formatted as by Integer#toString(int).
    • Subcase n = 1: dm is formatted as s1.0Ee. For example, 1 × 1023 is formatted as 1.0E23.
    • Subcase n > 1: dm is formatted as s1.s2snEe. For example, 123 × 10-21 is formatted as 1.23E-19.

To create localized string representations of a floating-point value, use subclasses of java.text.NumberFormat.

Parameters
f:float

the float to be converted.

Returns:String

a string representation of the argument.

toStringback to summary
public String toString()

Overrides java.lang.Object.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
java.lang.Float#toString(float)
valueOfback to summary
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:

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 Java Language Specification, except that underscores are not accepted between digits. 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. Note that the round-to-nearest 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.

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.

API Note

To interpret localized string representations of a floating-point value, or string representations that have non-ASCII digits, use java.text.NumberFormat. For example,

NumberFormat.getInstance(l).parse(s).floatValue();
NumberFormat.getInstance(l).parse(s).floatValue();
where l is the desired locale, or java.util.Locale#ROOT if locale insensitive.
Parameters
s:String

the string to be parsed.

Returns:Float

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

Exceptions
NumberFormatException:
if the string does not contain a parsable number.
See Also
Decimal ↔ Binary Conversion Issues
valueOfback to summary
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:float

a float value.

Returns:Float

a Float instance representing f.

Annotations
@IntrinsicCandidate
Since
1.5