public final class Float extends Number implements Comparable
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.
| Modifier and Type | Field and Description |
|---|---|
static float |
MAX_VALUE
A constant holding the largest positive finite value of type
float, (2-2-23)·2127. |
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 Class |
TYPE
The
Class instance representing the primitive type
float. |
| Constructor and Description |
|---|
Float(double value)
Constructs a newly allocated
Float object that
represents the argument converted to type float. |
Float(float value)
Constructs a newly allocated
Float object that
represents the primitive float argument. |
Float(String s)
Constructs a newly allocated
Float object that
represents the floating-point value of type float
represented by the string. |
| Modifier and Type | Method and Description |
|---|---|
byte |
byteValue()
Returns the value of this
Float as a
byte (by casting to a byte). |
static int |
compare(float f1,
float f2)
Compares the two specified
float values. |
int |
compareTo(Float anotherFloat)
Compares two
Float objects numerically. |
int |
compareTo(Object o)
Compares this
Float object to another object. |
double |
doubleValue()
Returns the
double value of this
Float object. |
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 this Float
object. |
int |
hashCode()
Returns a hash code for this
Float object. |
static float |
intBitsToFloat(int bits)
Returns the
float value corresponding to a given
bit represention. |
int |
intValue()
Returns the value of this
Float as an
int (by casting to type int). |
boolean |
isInfinite()
Returns
true if this Float 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 this Float 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 a long
(by casting to type long). |
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. |
short |
shortValue()
Returns the value of this
Float as a
short (by casting to a short). |
String |
toString()
Returns a string representation of this
Float object. |
static String |
toString(float f)
Returns a string representation of the
float
argument. |
static Float |
valueOf(String s)
Returns a
Float object holding the
float value represented by the argument string
s. |
public static final float POSITIVE_INFINITY
float. It is equal to the value returned by
Float.intBitsToFloat(0x7f800000).public static final float NEGATIVE_INFINITY
float. It is equal to the value returned by
Float.intBitsToFloat(0xff800000).public static final float NaN
float. It is equivalent to the value returned by
Float.intBitsToFloat(0x7fc00000).public static final float MAX_VALUE
float, (2-2-23)·2127.
It is equal to the value returned by
Float.intBitsToFloat(0x7f7fffff).public static final float MIN_VALUE
float, 2-149. It is equal to the value
returned by Float.intBitsToFloat(0x1).public static final Class TYPE
Class instance representing the primitive type
float.public Float(float value)
Float object that
represents the primitive float argument.value - the value to be represented by the Float.public Float(double value)
Float object that
represents the argument converted to type float.value - the value to be represented by the Float.public Float(String s) throws NumberFormatException
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.s - a string to be converted to a Float.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 magnitude m:
"Infinity"; thus, positive infinity produces
the result "Infinity" and negative infinity
produces the result "-Infinity".
"0.0"; thus, negative zero produces the result
"-0.0" and positive zero produces the result
"0.0".
.'
('\u002E'), followed by one or more
decimal digits representing the fractional part of
m.
.' ('\u002E'), followed by
decimal digits representing the fractional part of
a, followed by the letter 'E'
('\u0045'), followed by a representation
of n as a decimal integer, as produced by the
method Integer.toString(int)float. That is, suppose that x is the
exact mathematical value represented by the decimal
representation produced by this method for a finite nonzero
argument f. Then f must be the float
value nearest to x; or, if two float values are
equally close to x, then f must be one of
them and the least significant bit of the significand of
f must be 0.
To create localized string representations of a floating-point
value, use subclasses of NumberFormat.
f - the float to be converted.public static Float valueOf(String s) throws NumberFormatException
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. The rest of s should constitute a
FloatValue as described by the lexical syntax rules:
where Sign and FloatingPointLiteral are as defined in §3.10.2 of the Java Language Specification. If
- FloatValue:
- Signopt
NaN- Signopt
Infinity- Signopt FloatingPointLiteral
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"; this
exact decimal 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. Finally, a Float object
representing this float value is returned.
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.
s - the string to be parsed.Float object holding the value
represented by the String argument.NumberFormatException - if the string does not contain a
parsable number.public static float parseFloat(String s) throws NumberFormatException
float initialized to the value
represented by the specified String, as performed
by the valueOf method of class Float.s - the string to be parsed.float value represented by the string
argument.NumberFormatException - if the string does not contain a
parsable float.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 boolean isNaN()
true if this Float 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 this Float 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 primitive float value represented by this object
is converted to a String exactly as if by the method
toString of one argument.toString in class ObjectString representation of this object.toString(float)public byte byteValue()
Float as a
byte (by casting to a byte).public short shortValue()
Float as a
short (by casting to a short).shortValue in class Numberfloat value represented by this object
converted to type shortpublic int intValue()
Float as an
int (by casting to type int).public long longValue()
Float as a long
(by casting to type long).public float floatValue()
float value of this Float
object.floatValue in class Numberfloat value represented by this objectpublic double doubleValue()
double value of this
Float object.doubleValue in class Numberfloat value represented by this
object is converted to type double and the
result of the conversion is returned.public int hashCode()
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 in class ObjectObject.equals(java.lang.Object),
Hashtablepublic boolean equals(Object obj)
true if and only if the argument is not
null and is a Float object that
represents a float with the same value as the
float represented by this object. For this
purpose, two float values are considered to be the
same if and only if the method floatToIntBits(float)
returns the identical int value when applied to
each.
Note that in most cases, for two instances of class
Float, f1 and f2, the value
of f1.equals(f2) is true if and only if
f1.floatValue() == f2.floatValue()
also has the value true. However, there are two exceptions:
f1 and f2 both represent
Float.NaN, then the equals method returns
true, even though Float.NaN==Float.NaN
has the value false.
f1 represents +0.0f while
f2 represents -0.0f, or vice
versa, the equal test has the value
false, even though 0.0f==-0.0f
has the value true.
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 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).
value - a floating-point number.public static int floatToRawIntBits(float value)
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, intToRawIntBits 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.
value - a floating-point number.public static float intBitsToFloat(int bits)
float value corresponding to a given
bit represention.
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;
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.
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 primitive float values:
Float.NaN is considered by this method to
be equal to itself and greater than all other
float values
(including Float.POSITIVE_INFINITY).
0.0f is considered by this method to be greater
than -0.0f.
Float.compareTo(Object) (which
forwards its behavior to this method) obeys the general
contract for Comparable.compareTo, and that the
natural order on Floats is consistent
with equals.anotherFloat - the Float to be compared.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.Comparable.compareTo(Object)public int compareTo(Object o)
Float object to another object. If
the object is a Float, this function behaves like
compareTo(Float). Otherwise, it throws a
ClassCastException (as Float objects
are comparable only to other Float objects).compareTo in interface Comparableo - the Object to be compared.0 if the argument is a
Float numerically equal to this
Float; a value less than 0
if the argument is a Float numerically
greater than this Float; and a value
greater than 0 if the argument is a
Float numerically less than this
Float .ClassCastExceptionFloat.Comparablepublic 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 first float to compare.f2 - the second float to compare.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.Copyright © 2012. All Rights Reserved.