public final classFloatextendsNumberimplementsComparable<Float>
Float class wraps a value of primitive typefloat in an object. An object of typeFloat contains a single field whose type isfloat.In addition, this class provides several methods for converting afloat to aString and aString to afloat, as well as other constants and methods useful when dealing with afloat.
| Modifier and Type | Field | Description |
|---|---|---|
static int | BYTES | The number of bytes used to represent a float value. |
static int | MAX_EXPONENT | Maximum exponent a finite float variable may have. |
static float | MAX_VALUE | A constant holding the largest positive finite value of type float, (2-2-23)·2127. |
static int | MIN_EXPONENT | Minimum exponent a normalized float variable may have. |
static float | MIN_NORMAL | A constant holding the smallest positive normal value of type float, 2-126. |
static float | MIN_VALUE | A constant holding the smallest positive nonzero value of type float, 2-149. |
static float | NaN | A constant holding a Not-a-Number (NaN) value of type float. |
static float | NEGATIVE_INFINITY | A constant holding the negative infinity of type float. |
static float | POSITIVE_INFINITY | A constant holding the positive infinity of type float. |
static int | SIZE | The number of bits used to represent a float value. |
staticClass<Float> | TYPE | The Class instance representing the primitive typefloat. |
| Constructor | Description |
|---|---|
Float(double value) | Constructs a newly allocated Float object that represents the argument converted to typefloat. |
Float(float value) | Constructs a newly allocated Float object that represents the primitivefloat argument. |
Float(String s) | Constructs a newly allocated Float object that represents the floating-point value of typefloat represented by the string. |
| Modifier and Type | Method | Description |
|---|---|---|
byte | byteValue() | Returns the value of this Float as abyte after a narrowing primitive conversion. |
static int | compare(float f1, float f2) | Compares the two specified float values. |
int | compareTo(Float anotherFloat) | Compares two Float objects numerically. |
double | doubleValue() | Returns the value of this Float as adouble after a widening primitive conversion. |
boolean | equals(Object obj) | Compares this object against the specified object. |
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. |
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. |
float | floatValue() | Returns the float value of thisFloat object. |
int | hashCode() | Returns a hash code for this Float object. |
static int | hashCode(float value) | Returns a hash code for a float value; compatible withFloat.hashCode(). |
static float | intBitsToFloat(int bits) | Returns the float value corresponding to a given bit representation. |
int | intValue() | Returns the value of this Float as anint after a narrowing primitive conversion. |
static boolean | isFinite(float f) | Returns true if the argument is a finite floating-point value; returnsfalse otherwise (for NaN and infinity arguments). |
boolean | isInfinite() | Returns true if thisFloat value is infinitely large in magnitude,false otherwise. |
static boolean | isInfinite(float v) | Returns true if the specified number is infinitely large in magnitude,false otherwise. |
boolean | isNaN() | Returns true if thisFloat value is a Not-a-Number (NaN),false otherwise. |
static boolean | isNaN(float v) | Returns true if the specified number is a Not-a-Number (NaN) value,false otherwise. |
long | longValue() | Returns value of this Float as along after a narrowing primitive conversion. |
static float | max(float a, float b) | Returns the greater of two float values as if by callingMath.max. |
static float | min(float a, float b) | Returns the smaller of two float values as if by callingMath.min. |
static float | parseFloat(String s) | Returns a new float initialized to the value represented by the specifiedString, as performed by thevalueOf method of classFloat. |
short | shortValue() | Returns the value of this Float as ashort after a narrowing primitive conversion. |
static float | sum(float a, float b) | Adds two float values together as per the + operator. |
staticString | toHexString(float f) | Returns a hexadecimal string representation of the float argument. |
String | toString() | Returns a string representation of this Float object. |
staticString | toString(float f) | Returns a string representation of the float argument. |
staticFloat | valueOf(float f) | Returns a Float instance representing the specifiedfloat value. |
staticFloat | valueOf(String s) | Returns a Float object holding thefloat value represented by the argument strings. |
public static final float POSITIVE_INFINITY
float. It is equal to the value returned byFloat.intBitsToFloat(0x7f800000).public static final float NEGATIVE_INFINITY
float. It is equal to the value returned byFloat.intBitsToFloat(0xff800000).public static final float NaN
float. It is equivalent to the value returned byFloat.intBitsToFloat(0x7fc00000).public static final float MAX_VALUE
float, (2-2-23)·2127. It is equal to the hexadecimal floating-point literal0x1.fffffeP+127f and also equal toFloat.intBitsToFloat(0x7f7fffff).public static final float MIN_NORMAL
float, 2-126. It is equal to the hexadecimal floating-point literal0x1.0p-126f and also equal toFloat.intBitsToFloat(0x00800000).public static final float MIN_VALUE
float, 2-149. It is equal to the hexadecimal floating-point literal0x0.000002P-126f and also equal toFloat.intBitsToFloat(0x1).public static final int MAX_EXPONENT
float variable may have. It is equal to the value returned byMath.getExponent(Float.MAX_VALUE).public static final int MIN_EXPONENT
float variable may have. It is equal to the value returned byMath.getExponent(Float.MIN_NORMAL).public static final int SIZE
float value.public static final int BYTES
float value.public Float(float value)
Float object that represents the primitivefloat argument.value - the value to be represented by theFloat.public Float(double value)
Float object that represents the argument converted to typefloat.value - the value to be represented by theFloat.public Float(String s) throwsNumberFormatException
Float object that represents the floating-point value of typefloat represented by the string. The string is converted to afloat value as if by thevalueOf method.s - a string to be converted to aFloat.NumberFormatException - if the string does not contain a parsable number.valueOf(java.lang.String)public static String toString(float f)
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 magnitudem:"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 ofm..' ('\u002E'), followed by decimal digits representing the fractional part ofa, followed by the letter 'E' ('\u0045'), followed by a representation ofn as a decimal integer, as produced by the methodInteger.toString(int).float. That is, suppose thatx is the exact mathematical value represented by the decimal representation produced by this method for a finite nonzero argumentf. Thenf must be thefloat value nearest tox; or, if twofloat values are equally close tox, thenf must be one of them and the least significant bit of the significand off must be0.To create localized string representations of a floating-point value, use subclasses ofNumberFormat.
f - the float to be converted.public static String toHexString(float f)
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 magnitudem:"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 toInteger.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"p-126". Note that there must be at least one nonzero digit in a subnormal significand.| Floating-point Value | Hexadecimal 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 |
f - thefloat to be converted.public static Float valueOf(String s) throwsNumberFormatException
Float object holding thefloat value represented by the argument strings.Ifs isnull, then aNullPointerException is thrown.
Leading and trailing whitespace characters ins are ignored. Whitespace is removed as if by theString.trim() method; that is, both ASCII space and control characters are removed. The rest ofs should constitute aFloatValue as described by the lexical syntax rules:
whereSign,FloatingPointLiteral,HexNumeral,HexDigits,SignedInteger andFloatTypeSuffix are as defined in the lexical structure sections ofThe Java™ Language Specification, except that underscores are not accepted between digits. If
- FloatValue:
- Signopt
NaN- Signopt
Infinity- Signopt FloatingPointLiteral
- Signopt HexFloatingPointLiteral
- SignedInteger
- HexFloatingPointLiteral:
- HexSignificand BinaryExponent FloatTypeSuffixopt
- HexSignificand:
- HexNumeral
- HexNumeral
.0xHexDigitsopt.HexDigits0XHexDigitsopt.HexDigits
- BinaryExponent:
- BinaryExponentIndicator SignedInteger
- BinaryExponentIndicator:
pP
s does not have the form of aFloatValue, then aNumberFormatException 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 typefloat 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 ofs is large enough in magnitude (greater than or equal to (MAX_VALUE +ulp(MAX_VALUE)/2), rounding tofloat will result in an infinity and if the exact value ofs is small enough in magnitude (less than or equal toMIN_VALUE/2), rounding to float will result in a zero. Finally, after rounding aFloat object representing thisfloat value is returned.To interpret localized string representations of a floating-point value, use subclasses ofNumberFormat.
Note that trailing format specifiers, specifiers that determine the type of a floating-point literal (1.0f is afloat value;1.0d is adouble value), donot 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 todouble followed bydouble tofloat, isnot equivalent to converting a string directly tofloat. For example, if first converted to an intermediatedouble and then tofloat, the string"1.00000017881393421514957253748434595763683319091796875001d"
results in thefloat value1.0000002f; if the string is converted directly tofloat,1.0000001f results.
To avoid calling this method on an invalid string and having aNumberFormatException be thrown, the documentation forDouble.valueOf lists a regular expression which can be used to screen the input.
s - the string to be parsed.Float object holding the value represented by theString argument.NumberFormatException - if the string does not contain a parsable number.public static Float valueOf(float f)
Float instance representing the specifiedfloat value. If a newFloat instance is not required, this method should generally be used in preference to the constructorFloat(float), as this method is likely to yield significantly better space and time performance by caching frequently requested values.f - a float value.Float instance representingf.public static float parseFloat(String s) throwsNumberFormatException
float initialized to the value represented by the specifiedString, as performed by thevalueOf method of classFloat.s - the string to be parsed.float value represented by the string argument.NullPointerException - if the string is nullNumberFormatException - if the string does not contain a parsablefloat.valueOf(String)public static boolean isNaN(float v)
true if the specified number is a Not-a-Number (NaN) value,false otherwise.v - the value to be tested.true if the argument is NaN;false otherwise.public static boolean isInfinite(float v)
true if the specified number is infinitely large in magnitude,false otherwise.v - the value to be tested.true if the argument is positive infinity or negative infinity;false otherwise.public static boolean isFinite(float f)
true if the argument is a finite floating-point value; returnsfalse otherwise (for NaN and infinity arguments).f - thefloat value to be testedtrue if the argument is a finite floating-point value,false otherwise.public boolean isNaN()
true if thisFloat value is a Not-a-Number (NaN),false otherwise.true if the value represented by this object is NaN;false otherwise.public boolean isInfinite()
true if thisFloat value is infinitely large in magnitude,false otherwise.true if the value represented by this object is positive infinity or negative infinity;false otherwise.public String toString()
Float object. The primitivefloat value represented by this object is converted to aString exactly as if by the methodtoString of one argument.toString in class ObjectString representation of this object.toString(float)public byte byteValue()
Float as abyte after a narrowing primitive conversion.public short shortValue()
Float as ashort after a narrowing primitive conversion.shortValue in class Numberfloat value represented by this object converted to typeshortpublic int intValue()
Float as anint after a narrowing primitive conversion.public long longValue()
Float as along after a narrowing primitive conversion.public float floatValue()
float value of thisFloat object.floatValue in class Numberfloat value represented by this objectpublic double doubleValue()
Float as adouble after a widening primitive conversion.doubleValue in class Numberfloat value represented by this object converted to typedoublepublic int hashCode()
Float object. The result is the integer bit representation, exactly as produced by the methodfloatToIntBits(float), of the primitivefloat value represented by thisFloat object.hashCode in class ObjectObject.equals(java.lang.Object),System.identityHashCode(java.lang.Object)public static int hashCode(float value)
float value; compatible withFloat.hashCode().value - the value to hashfloat value.public boolean equals(Object obj)
true if and only if the argument is notnull and is aFloat object that represents afloat with the same value as thefloat represented by this object. For this purpose, twofloat values are considered to be the same if and only if the methodfloatToIntBits(float) returns the identicalint value when applied to each.Note that in most cases, for two instances of classFloat,f1 andf2, the value off1.equals(f2) istrue if and only if
f1.floatValue() == f2.floatValue()
also has the valuetrue. However, there are two exceptions:
f1 andf2 both representFloat.NaN, then theequals method returnstrue, even thoughFloat.NaN==Float.NaN has the valuefalse.f1 represents+0.0f whilef2 represents-0.0f, or vice versa, theequal test has the valuefalse, even though0.0f==-0.0f has the valuetrue.equals in class Objectobj - the object to be comparedtrue if the objects are the same;false otherwise.floatToIntBits(float)public static int floatToIntBits(float value)
Bit 31 (the bit that is selected by the mask0x80000000) represents the sign of the floating-point number. Bits 30-23 (the bits that are selected by the mask0x7f800000) represent the exponent. Bits 22-0 (the bits that are selected by the mask0x007fffff) represent the significand (sometimes called the mantissa) of the floating-point number.
If the argument is positive infinity, the result is0x7f800000.
If the argument is negative infinity, the result is0xff800000.
If the argument is NaN, the result is0x7fc00000.
In all cases, the result is an integer that, when given to theintBitsToFloat(int) method, will produce a floating-point value the same as the argument tofloatToIntBits (except all NaN values are collapsed to a single "canonical" NaN value).
value - a floating-point number.public static int floatToRawIntBits(float value)
Bit 31 (the bit that is selected by the mask0x80000000) represents the sign of the floating-point number. Bits 30-23 (the bits that are selected by the mask0x7f800000) represent the exponent. Bits 22-0 (the bits that are selected by the mask0x007fffff) represent the significand (sometimes called the mantissa) of the floating-point number.
If the argument is positive infinity, the result is0x7f800000.
If the argument is negative infinity, the result is0xff800000.
If the argument is NaN, the result is the integer representing the actual NaN value. Unlike thefloatToIntBits 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 theintBitsToFloat(int) method, will produce a floating-point value the same as the argument tofloatToRawIntBits.
value - a floating-point number.public static float intBitsToFloat(int bits)
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 is0x7f800000, the result is positive infinity.
If the argument is0xff800000, the result is negative infinity.
If the argument is any value in the range0x7f800001 through0x7fffffff or in the range0xff800001 through0xffffffff, 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 theFloat.floatToRawIntBits method.
In all other cases, lets,e, andm be three values that can be computed from the argument:
Then the floating-point result equals the value of the mathematical expressions·m·2e-150.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 afloat NaN with exactly same bit pattern as theint argument. IEEE 754 distinguishes between two kinds of NaNs, quiet NaNs andsignaling 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. SointBitsToFloat may not be able to return afloat with a signaling NaN bit pattern. Consequently, for someint values,floatToRawIntBits(intBitsToFloat(start)) maynot equalstart. 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.
bits - an integer.float floating-point value with the same bit pattern.public int compareTo(Float anotherFloat)
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 primitivefloat 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 than-0.0f.Float objects imposed by this method isconsistent with equals.compareTo in interface Comparable<Float>anotherFloat - theFloat to be compared.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.Comparable.compareTo(Object)public static int compare(float f1, float f2)
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))
f1 - the firstfloat to compare.f2 - the secondfloat to compare.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.public static float sum(float a, float b)
float values together as per the + operator.a - the first operandb - the second operanda andbBinaryOperatorpublic static float max(float a, float b)
float values as if by callingMath.max.a - the first operandb - the second operanda andbBinaryOperatorpublic static float min(float a, float b)
float values as if by callingMath.min.a - the first operandb - the second operanda andbBinaryOperator