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JavaTM 2 Platform Std. Ed. v1.3 |
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java.lang.Object
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+--java.lang.Number
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+--java.lang.Float
The Float class wraps a value of primitive type float in
an object. An object of type Float contains a single
field whose type is float.
In addition, this class provides several methods for converting a
float to a String and a
String to a float, as well as other
constants and methods useful when dealing with a
float.
| Field Summary | |
static float |
MAX_VALUE
The largest positive value of type float. |
static float |
MIN_VALUE
The smallest positive value of type float. |
static float |
NaN
The Not-a-Number (NaN) value of type float. |
static float |
NEGATIVE_INFINITY
The negative infinity of type float. |
static float |
POSITIVE_INFINITY
The positive infinity of type float. |
static Class |
TYPE
The Class object representing the primitive type float. |
| Constructor Summary | |
Float(double value)
Constructs a newly allocated Floatobject 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. |
|
| Method Summary | |
byte |
byteValue()
Returns the value of this Float as a byte (by casting to a byte). |
int |
compareTo(Float anotherFloat)
Compares two Floats numerically. |
int |
compareTo(Object o)
Compares this Float to another Object. |
double |
doubleValue()
Returns the double value of this Float object. |
boolean |
equals(Object obj)
Compares this object against some other object. |
static int |
floatToIntBits(float value)
Returns the bit represention of a single-float value. |
static int |
floatToRawIntBits(float value)
Returns the bit represention of a single-float value. |
float |
floatValue()
Returns the float value of this Float object. |
int |
hashCode()
Returns a hashcode for this Float object. |
static float |
intBitsToFloat(int bits)
Returns the single-float corresponding to a given bit represention. |
int |
intValue()
Returns the integer value of this Float (by casting to an int). |
boolean |
isInfinite()
Returns true if this Float value is infinitely large in magnitude. |
static boolean |
isInfinite(float v)
Returns true if the specified number is infinitely large in magnitude. |
boolean |
isNaN()
Returns true if this Float value is Not-a-Number (NaN). |
static boolean |
isNaN(float v)
Returns true if the specified number is the special Not-a-Number (NaN) value. |
long |
longValue()
Returns the long value of this Float (by casting to a 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 Double. |
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 for the specified float value. |
static Float |
valueOf(String s)
Returns the floating point value represented by the specified String. |
| Methods inherited from class java.lang.Object |
clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
| Field Detail |
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 equal to the value returned by
Float.intBitsToFloat(0x7fc00000).public static final float MAX_VALUE
float. It is
equal to the value returned by
Float.intBitsToFloat(0x7f7fffff).public static final float MIN_VALUE
float. It
is equal to the value returned by
Float.intBitsToFloat(0x1).public static final Class TYPE
| Constructor Detail |
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)
Floatobject 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)| Method Detail |
public static String toString(float f)
Integer.toString(int) of one argument.
f - the float to be converted.
public static Float valueOf(String s)
throws NumberFormatException
s is interpreted as the representation of a
floating-point value and a Float object representing that
value is created and returned.
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:
FloatValue:
Signopt FloatingPointLiteral
where Sign, FloatingPointLiteral are as defined in
§3.10.2 of the
Java Language
Specification. If it does not have the form of a FloatValue,
then a NumberFormatException is thrown. Otherwise, it 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.s - the string to be parsed.Float initialized to 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
String, as performed by the valueOf
method of class Double.s - the string to be parsed.NumberFormatException - if the string does not contain a
parsable float.Double.valueOf(String)public static boolean isNaN(float v)
v - the value to be tested.true if the argument is NaN;
false otherwise.public static boolean isInfinite(float v)
v - the value to be tested.true if the argument is positive infinity or
negative infinity; false otherwise.public boolean isNaN()
Float value is Not-a-Number (NaN).true if the value represented by this object is
NaN; false otherwise.public boolean isInfinite()
true if the value represented by this object is
positive infinity or negative infinity;
false otherwise.public String toString()
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()
byteValue in class Numberpublic short shortValue()
shortValue in class Numberpublic int intValue()
intValue in class Numberfloat value represented by this object
converted to type int and the result of the
conversion is returned.public long longValue()
longValue in class Numberfloat value represented by this object is
converted to type long and the result of the
conversion is returned.public float floatValue()
floatValue in class Numberfloat value represented by this object.public double doubleValue()
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()
floatToIntBits(float), of the primitive float
value represented by this Float object.hashCode in class Objectpublic boolean equals(Object obj)
true if and only if the argument is
not null and is a Float object that
represents a float that has the identical bit pattern
to the bit pattern of 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 same 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)
0x80000000) represents the sign of the floating-point
number.
0x7f800000) represent the exponent.
0x007fffff) represent the significand (sometimes called
the mantissa) of the floating-point number.
0x7f800000.
0xff800000.
0x7fc00000.
intBitsToFloat(int) method, will produce a floating-point
value equal to the argument to floatToIntBits.value - a floating-point number.public static int floatToRawIntBits(float value)
0x80000000) represents the sign of the floating-point
number.
0x7f800000) represent the exponent.
0x007fffff) represent the significand (sometimes called
the mantissa) of the floating-point number.
0x7f800000.
0xff800000.
If the argument is NaN, the result is the integer
representing the actual NaN value. Unlike the floatToIntBits
method, intToRawIntBits does not collapse NaN values.
intBitsToFloat(int) method, will produce a floating-point
value equal to the argument to floatToRawIntBits.value - a floating-point number.public static float intBitsToFloat(int bits)
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
NaN. All IEEE 754 NaN values of type float are, in effect,
lumped together by the Java programming language into a single
float value called NaN. Distinct values of NaN are only
accessible by use of the Float.floatToRawIntBits method.
In all other cases, let s, e, and m be three values that can be computed from the argument:
int s = ((bits >> 31) == 0) ? 1 : -1;
int e = ((bits >> 23) & 0xff);
int m = (e == 0) ?
(bits & 0x7fffff) << 1 :
(bits & 0x7fffff) | 0x800000;
Then the floating-point result equals the value of the mathematical
expression s·m·2e-150.bits - an integer.public int compareTo(Float anotherFloat)
<, <=,
==, >= >) when applied to primitive floats:
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.
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)
compareTo(Float). Otherwise,
it throws a ClassCastException (as Floats are comparable
only to other Floats).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.ClassCastException - if the argument is not a
Float.Comparable
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JavaTM 2 Platform Std. Ed. v1.3 |
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