Float

See also:

• ERROR(href="https://standards.ieee.org/ieee/754/6210/"> IEEE Standard for Floating-Point Arithmetic/ IEEE Standard for Floating-Point Arithmetic)

BYTES

public static final int BYTES

The number of bytes used to represent a float value.

Constant Value: 4 (0x00000004)

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).

Constant Value: 127 (0x0000007f)

MAX_VALUE

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).

Constant Value: 3.4028235E38

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).

Constant Value: -126 (0xffffff82)

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

Constant Value: 1.1754944E-38

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

Constant Value: 1.4E-45

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).

Constant Value: -Infinity

NaN

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).

Constant Value: NaN

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).

Constant Value: Infinity

PRECISION

public static final int PRECISION

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

Constant Value: 24 (0x00000018)

SIZE

public static final int SIZE

The number of bits used to represent a float value.

Constant Value: 32 (0x00000020)

TYPE

public static final Class<Float> TYPE

The Class instance representing the primitive type float.

Float

public Float (double value)

This constructor is deprecated.
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.

Float

public Float (float value)

This constructor is deprecated.
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.

Float

public Float (String s)

This constructor is deprecated.
It is rarely appropriate to use this constructor. Use parseFloat(java.lang.String) to convert a string to a float primitive, or use valueOf(java.lang.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.

byteValue

public byte byteValue ()

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

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:

    Float.valueOf(f1).compareTo(Float.valueOf(f2))
 

compareTo

public int compareTo (Float anotherFloat)

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).

doubleValue

public double doubleValue ()

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

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.

float16ToFloat

public static float float16ToFloat (short floatBinary16)

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

floatToFloat16

public static short floatToFloat16 (float f)

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.

floatToIntBits

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).

floatToRawIntBits

public static 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.

floatValue

public float floatValue ()

Returns the float value of this Float object.

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.

hashCode

public static int hashCode (float value)

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

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 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: lang="java" : 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·2^e-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.

intValue

public int intValue ()

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

isFinite

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).

isInfinite

public boolean isInfinite ()

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

isInfinite

public static boolean isInfinite (float v)

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

isNaN

public static boolean isNaN (float v)

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

isNaN

public boolean isNaN ()

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

longValue

public long longValue ()

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

max

public static float max (float a, 
                float b)

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

min

public static float min (float a, 
                float b)

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

parseFloat

public static 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.

shortValue

public short shortValue ()

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

sum

public static float sum (float a, 
                float b)

Adds two float values together as per the + operator.

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 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.

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.

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".
  • Otherwise m is positive and finite. It is converted to a string in two stages:
    • Selection of a decimal: A well-defined decimal d_m 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 d_m 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 10^n-1 ≤ s < 10ⁿ.

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

• Case -3 ≤ e < 0: d_m is formatted as 0.0…0s₁…s_n, 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: d_m is formatted as s₁…s_n0…0.0, where there are exactly i zeroes between s_n and the decimal point. For example, 123 × 10² is formatted as 12300.0.
  • Subcase i < 0: d_m is formatted as s₁…s_n+i.s_n+i+1…s_n, 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 d_m. Here e is formatted as by Integer.toString(int).
  • Subcase n = 1: d_m is formatted as s₁.0Ee. For example, 1 × 10²³ is formatted as 1.0E23.
  • Subcase n > 1: d_m is formatted as s₁.s₂…s_nEe. For example, 123 × 10^-21 is formatted as 1.23E-19.

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

valueOf

public static 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 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:

Sign_opt NaN

Sign_opt Infinity

Sign_opt FloatingPointLiteral

Sign_opt HexFloatingPointLiteral

SignedInteger

HexFloatingPointLiteral:

HexSignificand BinaryExponent FloatTypeSuffix_opt

HexSignificand:

HexNumeral

HexNumeral .

0x HexDigits_opt . HexDigits

0X HexDigits_opt . HexDigits

BinaryExponent:

BinaryExponentIndicator SignedInteger

BinaryExponentIndicator:

p

P

To interpret localized string representations of a floating-point value, use subclasses of NumberFormat.

Note that trailing format specifiers, specifiers that determine the type of a floating-point literal (1.0f is a float value; 1.0d is a double value), do not influence the results of this method. In other words, the numerical value of the input string is converted directly to the target floating-point type. In general, the two-step sequence of conversions, string to double followed by double to float, is not equivalent to converting a string directly to float. For example, if first converted to an intermediate double and then to float, the string
"1.00000017881393421514957253748434595763683319091796875001d"
results in the float value 1.0000002f; if the string is converted directly to float, 1.0000001f results.

To avoid calling this method on an invalid string and having a NumberFormatException be thrown, the documentation for Double.valueOf lists a regular expression which can be used to screen the input.

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.