Floatpublic final class Float extends Number implements ComparableThe 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 . 
Fields Summary 

public static final float  POSITIVE_INFINITYA constant holding the positive infinity of type
float . It is equal to the value returned by
Float.intBitsToFloat(0x7f800000) .  public static final float  NEGATIVE_INFINITYA constant holding the negative infinity of type
float . It is equal to the value returned by
Float.intBitsToFloat(0xff800000) .  public static final float  NaNA constant holding a NotaNumber (NaN) value of type
float . It is equivalent to the value returned by
Float.intBitsToFloat(0x7fc00000) .  public static final float  MAX_VALUEA constant holding the largest positive finite value of type
float , (22^{23})·2^{127}.
It is equal to the hexadecimal floatingpoint literal
0x1.fffffeP+127f and also equal to
Float.intBitsToFloat(0x7f7fffff) .  public static final float  MIN_VALUEA constant holding the smallest positive nonzero value of type
float , 2^{149}. It is equal to the
hexadecimal floatingpoint literal 0x0.000002P126f
and also equal to Float.intBitsToFloat(0x1) .  public static final int  SIZEThe number of bits used to represent a float value.  public static final Class  TYPEThe Class instance representing the primitive type
float .  private final float  valueThe value of the Float.  private static final long  serialVersionUIDuse serialVersionUID from JDK 1.0.2 for interoperability 
Constructors Summary 

public Float(String s)Constructs a newly allocated Float object that
represents the floatingpoint value of type float
represented by the string. The string is converted to a
float value as if by the valueOf method.
// REMIND: this is inefficient
this(valueOf(s).floatValue());
 public Float(float value)Constructs a newly allocated Float object that
represents the primitive float argument.
this.value = value;
 public Float(double value)Constructs a newly allocated Float object that
represents the argument converted to type float .
this.value = (float)value;

Methods Summary 

public byte  byteValue()Returns the value of this Float as a
byte (by casting to a byte ).
return (byte)value;
 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:
new Float(f1).compareTo(new 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)
 public int  compareTo(java.lang.Float anotherFloat)Compares two 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 .
This ensures that the natural ordering of Float
objects imposed by this method is consistent with equals.
return Float.compare(value, anotherFloat.value);
 public double  doubleValue()Returns the double value of this
Float object.
return (double)value;
 public boolean  equals(java.lang.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 {@link #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:
 If
f1 and f2 both represent
Float.NaN , then the equals method returns
true , even though Float.NaN==Float.NaN
has the value false .
 If
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 .
This definition allows hash tables to operate properly.
return (obj instanceof Float)
&& (floatToIntBits(((Float)obj).value) == floatToIntBits(value));
 public static native int  floatToIntBits(float value)Returns a representation of the specified floatingpoint value
according to the IEEE 754 floatingpoint "single format" bit
layout.
Bit 31 (the bit that is selected by the mask
0x80000000 ) represents the sign of the floatingpoint
number.
Bits 3023 (the bits that are selected by the mask
0x7f800000 ) represent the exponent.
Bits 220 (the bits that are selected by the mask
0x007fffff ) represent the significand (sometimes called
the mantissa) of the floatingpoint 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
{@link #intBitsToFloat(int)} method, will produce a floatingpoint
value the same as the argument to 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 floatingpoint value
according to the IEEE 754 floatingpoint "single format" bit
layout, preserving NotaNumber (NaN) values.
Bit 31 (the bit that is selected by the mask
0x80000000 ) represents the sign of the floatingpoint
number.
Bits 3023 (the bits that are selected by the mask
0x7f800000 ) represent the exponent.
Bits 220 (the bits that are selected by the mask
0x007fffff ) represent the significand (sometimes called
the mantissa) of the floatingpoint 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
{@link #intBitsToFloat(int)} method, will produce a
floatingpoint value the same as the argument to
floatToRawIntBits .
 public float  floatValue()Returns the float value of this Float
object.
return value;
 public int  hashCode()Returns a hash code for this Float object. The
result is the integer bit representation, exactly as produced
by the method {@link #floatToIntBits(float)}, of the primitive
float value represented by this Float
object.
return floatToIntBits(value);
 public static native float  intBitsToFloat(int bits)Returns the float value corresponding to a given
bit representation.
The argument is considered to be a representation of a
floatingpoint value according to the IEEE 754 floatingpoint
"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
floatingpoint 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;
Then the floatingpoint result equals the value of the mathematical
expression s·m·2^{e150}.
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.
 public int  intValue()Returns the value of this Float as an
int (by casting to type int ).
return (int)value;
 public boolean  isInfinite()Returns true if this Float value is
infinitely large in magnitude, false otherwise.
return isInfinite(value);
 public static boolean  isInfinite(float v)Returns true if the specified number is infinitely
large in magnitude, false otherwise.
return (v == POSITIVE_INFINITY)  (v == NEGATIVE_INFINITY);
 public boolean  isNaN()Returns true if this Float value is a
NotaNumber (NaN), false otherwise.
return isNaN(value);
 public static boolean  isNaN(float v)Returns true if the specified number is a
NotaNumber (NaN) value, false otherwise.
return (v != v);
 public long  longValue()Returns value of this Float as a long
(by casting to type long ).
return (long)value;
 public static float  parseFloat(java.lang.String s)Returns a new float initialized to the value
represented by the specified String , as performed
by the valueOf method of class Float .
return FloatingDecimal.readJavaFormatString(s).floatValue();
 public short  shortValue()Returns the value of this Float as a
short (by casting to a short ).
return (short)value;
 public static java.lang.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 {@link Integer#toString(int) 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
"p126" . Note that there must be at
least one nonzero digit in a subnormal significand.
Examples
Floatingpoint Value  Hexadecimal String 

1.0  0x1.0p0 
1.0  0x1.0p0 
2.0  0x1.0p1 
3.0  0x1.8p1 
0.5  0x1.0p1 
0.25  0x1.0p2 
Float.MAX_VALUE 
0x1.fffffep127 
Minimum Normal Value 
0x1.0p126 
Maximum Subnormal Value 
0x0.fffffep126 
Float.MIN_VALUE 
0x0.000002p126 
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("p1022$", "p126");
}
else // double string will be the same as float string
return Double.toHexString(f);
 public static java.lang.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" .
 If m is greater than or equal to 10^{3} but
less than 10^{7}, then it is represented as the
integer part of m, in decimal form with no leading
zeroes, followed by '
. '
('\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 10^{7}, then it is represented in
socalled "computerized scientific notation." Let n
be the unique integer such that 10^{n }<=
m < 10^{n+1}; then let a
be the mathematically exact quotient of m and
10^{n} so that 1 <= a < 10.
The magnitude is then represented as the integer part of
a, as a single decimal digit, followed by
'
. ' ('\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 {@link
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
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 floatingpoint
value, use subclasses of {@link java.text.NumberFormat}.
return new FloatingDecimal(f).toJavaFormatString();
 public java.lang.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.
return String.valueOf(value);
 public static java.lang.Float  valueOf(java.lang.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 {@link
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
where Sign, FloatingPointLiteral,
HexNumeral, HexDigits, SignedInteger and
FloatTypeSuffix are as defined in the lexical structure
sections of the of the Java Language
Specification. If 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" 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 float
by the usual roundtonearest rule of IEEE 754 floatingpoint
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
floatingpoint value, use subclasses of {@link
java.text.NumberFormat}.
Note that trailing format specifiers, specifiers that
determine the type of a floatingpoint 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 floatingpoint type. In general, the
twostep 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 a invalid string and having
a NumberFormatException be thrown, the documentation
for {@link Double#valueOf Double.valueOf} lists a regular
expression which can be used to screen the input.
return new Float(FloatingDecimal.readJavaFormatString(s).floatValue());
 public static java.lang.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
{@link #Float(float)}, as this method is likely to yield
significantly better space and time performance by caching
frequently requested values.
return new Float(f);

