| Method from java.lang.Float Detail: |
|---|
 public byte byteValue() {
return (byte)value;
}
Returns the value of this {@code Float} as a {@code byte} (by
casting to a {@code byte}). |
public static int compare(float f1,
float f2) {
if (f1 < f2)
return -1; // Neither val is NaN, thisVal is smaller
if (f1 > f2)
return 1; // Neither val is NaN, thisVal is larger
int thisBits = Float.floatToIntBits(f1);
int anotherBits = Float.floatToIntBits(f2);
return (thisBits == anotherBits ? 0 : // Values are equal
(thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
1)); // (0.0, -0.0) or (NaN, !NaN)
} Compares the two specified {@code 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))
|
public int compareTo(Float anotherFloat) {
return Float.compare(value, anotherFloat.value);
} Compares two {@code 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 ({@code <, <=, ==, >=, >}) when
applied to primitive {@code float} values:
-
{@code Float.NaN} is considered by this method to
be equal to itself and greater than all other
{@code float} values
(including {@code Float.POSITIVE_INFINITY}).
-
{@code 0.0f} is considered by this method to be greater
than {@code -0.0f}.
This ensures that the natural ordering of {@code Float}
objects imposed by this method is consistent with equals. |
public double doubleValue() {
return (double)value;
} Returns the {@code double} value of this {@code Float} object. |
public boolean equals(Object obj) {
return (obj instanceof Float)
&& (floatToIntBits(((Float)obj).value) == floatToIntBits(value));
} Compares this object against the specified object. The result
is {@code true} if and only if the argument is not
{@code null} and is a {@code Float} object that
represents a {@code float} with the same value as the
{@code float} represented by this object. For this
purpose, two {@code float} values are considered to be the
same if and only if the method #floatToIntBits(float)
returns the identical {@code int} value when applied to
each.
Note that in most cases, for two instances of class
{@code Float}, {@code f1} and {@code f2}, the value
of {@code f1.equals(f2)} is {@code true} if and only if
f1.floatValue() == f2.floatValue()
also has the value {@code true}. However, there are two exceptions:
- If {@code f1} and {@code f2} both represent
{@code Float.NaN}, then the {@code equals} method returns
{@code true}, even though {@code Float.NaN==Float.NaN}
has the value {@code false}.
- If {@code f1} represents {@code +0.0f} while
{@code f2} represents {@code -0.0f}, or vice
versa, the {@code equal} test has the value
{@code false}, even though {@code 0.0f==-0.0f}
has the value {@code true}.
This definition allows hash tables to operate properly. |
public static int floatToIntBits(float value) {
int result = floatToRawIntBits(value);
// Check for NaN based on values of bit fields, maximum
// exponent and nonzero significand.
if ( ((result & FloatConsts.EXP_BIT_MASK) ==
FloatConsts.EXP_BIT_MASK) &&
(result & FloatConsts.SIGNIF_BIT_MASK) != 0)
result = 0x7fc00000;
return result;
} 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
{@code 0x80000000}) represents the sign of the floating-point
number.
Bits 30-23 (the bits that are selected by the mask
{@code 0x7f800000}) represent the exponent.
Bits 22-0 (the bits that are selected by the mask
{@code 0x007fffff}) represent the significand (sometimes called
the mantissa) of the floating-point number.
If the argument is positive infinity, the result is
{@code 0x7f800000}.
If the argument is negative infinity, the result is
{@code 0xff800000}.
If the argument is NaN, the result is {@code 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 {@code floatToIntBits}
(except all NaN values are collapsed to a single
"canonical" NaN value). |
 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
{@code 0x80000000}) represents the sign of the floating-point
number.
Bits 30-23 (the bits that are selected by the mask
{@code 0x7f800000}) represent the exponent.
Bits 22-0 (the bits that are selected by the mask
{@code 0x007fffff}) represent the significand (sometimes called
the mantissa) of the floating-point number.
If the argument is positive infinity, the result is
{@code 0x7f800000}.
If the argument is negative infinity, the result is
{@code 0xff800000}.
If the argument is NaN, the result is the integer representing
the actual NaN value. Unlike the {@code floatToIntBits}
method, {@code 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
{@code floatToRawIntBits}. |
public float floatValue() {
return value;
} Returns the {@code float} value of this {@code Float} object. |
public int hashCode() {
return floatToIntBits(value);
} Returns a hash code for this {@code Float} object. The
result is the integer bit representation, exactly as produced
by the method #floatToIntBits(float) , of the primitive
{@code float} value represented by this {@code Float}
object. |
public static native float intBitsToFloat(int bits) Returns the {@code 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 {@code 0x7f800000}, the result is positive
infinity.
If the argument is {@code 0xff800000}, the result is negative
infinity.
If the argument is any value in the range
{@code 0x7f800001} through {@code 0x7fffffff} or in
the range {@code 0xff800001} through
{@code 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 {@code 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.
Note that this method may not be able to return a
{@code float} NaN with exactly same bit pattern as the
{@code 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 {@code intBitsToFloat} may
not be able to return a {@code float} with a signaling NaN
bit pattern. Consequently, for some {@code int} values,
{@code floatToRawIntBits(intBitsToFloat(start))} may
not equal {@code 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. |
public int intValue() {
return (int)value;
} Returns the value of this {@code Float} as an {@code int} (by
casting to type {@code int}). |
public boolean isInfinite() {
return isInfinite(value);
} Returns {@code true} if this {@code Float} value is
infinitely large in magnitude, {@code false} otherwise. |
public static boolean isInfinite(float v) {
return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
} Returns {@code true} if the specified number is infinitely
large in magnitude, {@code false} otherwise. |
public boolean isNaN() {
return isNaN(value);
} Returns {@code true} if this {@code Float} value is a
Not-a-Number (NaN), {@code false} otherwise. |
public static boolean isNaN(float v) {
return (v != v);
} Returns {@code true} if the specified number is a
Not-a-Number (NaN) value, {@code false} otherwise. |
public long longValue() {
return (long)value;
} Returns value of this {@code Float} as a {@code long} (by
casting to type {@code long}). |
public static float parseFloat(String s) throws NumberFormatException {
return FloatingDecimal.readJavaFormatString(s).floatValue();
} Returns a new {@code float} initialized to the value
represented by the specified {@code String}, as performed
by the {@code valueOf} method of class {@code Float}. |
public short shortValue() {
return (short)value;
} Returns the value of this {@code Float} as a {@code short} (by
casting to a {@code short}). |
public static String toHexString(float f) {
if (Math.abs(f) < FloatConsts.MIN_NORMAL
&& f != 0.0f ) {// float subnormal
// Adjust exponent to create subnormal double, then
// replace subnormal double exponent with subnormal float
// exponent
String s = Double.toHexString(FpUtils.scalb((double)f,
/* -1022+126 */
DoubleConsts.MIN_EXPONENT-
FloatConsts.MIN_EXPONENT));
return s.replaceFirst("p-1022$", "p-126");
}
else // double string will be the same as float string
return Double.toHexString(f);
} Returns a hexadecimal string representation of the
{@code float} argument. All characters mentioned below are
ASCII characters.
- If the argument is NaN, the result is the string
"{@code 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 '{@code -}'
(
'\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
{@code "Infinity"}; thus, positive infinity produces the
result {@code "Infinity"} and negative infinity produces
the result {@code "-Infinity"}.
- If m is zero, it is represented by the string
{@code "0x0.0p0"}; thus, negative zero produces the result
{@code "-0x0.0p0"} and positive zero produces the result
{@code "0x0.0p0"}.
- If m is a {@code float} value with a
normalized representation, substrings are used to represent the
significand and exponent fields. The significand is
represented by the characters {@code "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 {@code "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 {@code float} value with a subnormal
representation, the significand is represented by the
characters {@code "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
{@code "p-126"}. Note that there must be at
least one nonzero digit in a subnormal significand.
Examples
| Floating-point Value | Hexadecimal String |
|---|
| {@code 1.0} | {@code 0x1.0p0} |
| {@code -1.0} | {@code -0x1.0p0} |
| {@code 2.0} | {@code 0x1.0p1} |
| {@code 3.0} | {@code 0x1.8p1} |
| {@code 0.5} | {@code 0x1.0p-1} |
| {@code 0.25} | {@code 0x1.0p-2} |
| {@code Float.MAX_VALUE} |
{@code 0x1.fffffep127} |
| {@code Minimum Normal Value} |
{@code 0x1.0p-126} |
| {@code Maximum Subnormal Value} |
{@code 0x0.fffffep-126} |
| {@code Float.MIN_VALUE} |
{@code 0x0.000002p-126} |
|
public String toString() {
return String.valueOf(value);
} Returns a string representation of this {@code Float} object.
The primitive {@code float} value represented by this object
is converted to a {@code String} exactly as if by the method
{@code toString} of one argument. |
public static String toString(float f) {
return new FloatingDecimal(f).toJavaFormatString();
} Returns a string representation of the {@code float}
argument. All characters mentioned below are ASCII characters.
- If the argument is NaN, the result is the string
"{@code 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
'{@code -}' (
'\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
{@code "Infinity"}; thus, positive infinity produces
the result {@code "Infinity"} and negative infinity
produces the result {@code "-Infinity"}.
- If m is zero, it is represented by the characters
{@code "0.0"}; thus, negative zero produces the result
{@code "-0.0"} and positive zero produces the result
{@code "0.0"}.
- If m is greater than or equal to 10-3 but
less than 107, then it is represented as the
integer part of m, in decimal form with no leading
zeroes, followed by '{@code .}'
(
'\u002E'), followed by one or more
decimal digits representing the fractional part of
m.
- If m is less than 10-3 or greater than or
equal to 107, then it is represented in
so-called "computerized scientific notation." Let n
be the unique integer such that 10n ≤
m {@literal <} 10n+1; then let a
be the mathematically exact quotient of m and
10n so that 1 ≤ a {@literal <} 10.
The magnitude is then represented as the integer part of
a, as a single decimal digit, followed by
'{@code .}' (
'\u002E'), followed by
decimal digits representing the fractional part of
a, followed by the letter '{@code E}'
('\u0045'), followed by a representation
of n as a decimal integer, as produced by the
method java.lang.Integer#toString(int) .
How many digits must be printed for the fractional part of
m or a? There must be at least one digit
to represent the fractional part, and beyond that as many, but
only as many, more digits as are needed to uniquely distinguish
the argument value from adjacent values of type
{@code 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 {@code float}
value nearest to x; or, if two {@code 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 {@code 0}.
To create localized string representations of a floating-point
value, use subclasses of java.text.NumberFormat . |
public static Float valueOf(String s) throws NumberFormatException {
return new Float(FloatingDecimal.readJavaFormatString(s).floatValue());
} Returns a {@code Float} object holding the
{@code float} value represented by the argument string
{@code s}.
If {@code s} is {@code null}, then a
{@code NullPointerException} is thrown.
Leading and trailing whitespace characters in {@code 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 {@code s} should
constitute a FloatValue as described by the lexical
syntax rules:
- FloatValue:
- Signopt {@code NaN}
- Signopt {@code Infinity}
- Signopt FloatingPointLiteral
- Signopt HexFloatingPointLiteral
- SignedInteger
- HexFloatingPointLiteral:
- HexSignificand BinaryExponent FloatTypeSuffixopt
- HexSignificand:
- HexNumeral
- HexNumeral {@code .}
- {@code 0x} HexDigitsopt
{@code .} HexDigits
- {@code 0X} HexDigitsopt
{@code .} HexDigits
- BinaryExponent:
- BinaryExponentIndicator SignedInteger
- BinaryExponentIndicator:
- {@code p}
- {@code P}
where Sign, FloatingPointLiteral,
HexNumeral, HexDigits, SignedInteger and
FloatTypeSuffix are as defined in the lexical structure
sections of the Java Language
Specification. If {@code s} does not have the form of
a FloatValue, then a {@code NumberFormatException}
is thrown. Otherwise, {@code 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 {@code 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 {@code Float} object representing this
{@code float} value is returned.
To interpret localized string representations of a
floating-point value, use subclasses of java.text.NumberFormat .
Note that trailing format specifiers, specifiers that
determine the type of a floating-point literal
({@code 1.0f} is a {@code float} value;
{@code 1.0d} is a {@code 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 {@code double}
followed by {@code double} to {@code float}, is
not equivalent to converting a string directly to
{@code float}. For example, if first converted to an
intermediate {@code double} and then to
{@code float}, the string
{@code "1.00000017881393421514957253748434595763683319091796875001d"}
results in the {@code float} value
{@code 1.0000002f}; if the string is converted directly to
{@code float}, 1.0000001f results.
To avoid calling this method on an invalid string and having
a {@code NumberFormatException} be thrown, the documentation
for Double.valueOf lists a regular
expression which can be used to screen the input. |
public static Float valueOf(float f) {
return new Float(f);
} Returns a {@code Float} instance representing the specified
{@code float} value.
If a new {@code 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. |
java.lang.Number
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