
Java^{TM} 2 Platform Standard Ed. 5.0 

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java.lang.Object java.lang.Number java.lang.Double
public final class Double
The Double
class wraps a value of the primitive type
double
in an object. An object of type
Double
contains a single field whose type is
double
.
In addition, this class provides several methods for converting a
double
to a String
and a
String
to a double
, as well as other
constants and methods useful when dealing with a
double
.
Field Summary  

static double 
MAX_VALUE
A constant holding the largest positive finite value of type double ,
(22^{52})·2^{1023}. 
static double 
MIN_VALUE
A constant holding the smallest positive nonzero value of type double , 2^{1074}. 
static double 
NaN
A constant holding a NotaNumber (NaN) value of type double . 
static double 
NEGATIVE_INFINITY
A constant holding the negative infinity of type double . 
static double 
POSITIVE_INFINITY
A constant holding the positive infinity of type double . 
static int 
SIZE
The number of bits used to represent a double value. 
static Class<Double> 
TYPE
The Class instance representing the primitive type
double . 
Constructor Summary  

Double(double value)
Constructs a newly allocated Double object that
represents the primitive double argument. 

Double(String s)
Constructs a newly allocated Double object that
represents the floatingpoint value of type double
represented by the string. 
Method Summary  

byte 
byteValue()
Returns the value of this Double as a byte (by
casting to a byte ). 
static int 
compare(double d1,
double d2)
Compares the two specified double values. 
int 
compareTo(Double anotherDouble)
Compares two Double objects numerically. 
static long 
doubleToLongBits(double value)
Returns a representation of the specified floatingpoint value according to the IEEE 754 floatingpoint "double format" bit layout. 
static long 
doubleToRawLongBits(double value)
Returns a representation of the specified floatingpoint value according to the IEEE 754 floatingpoint "double format" bit layout, preserving NotaNumber (NaN) values. 
double 
doubleValue()
Returns the double value of this
Double object. 
boolean 
equals(Object obj)
Compares this object against the specified object. 
float 
floatValue()
Returns the float value of this
Double object. 
int 
hashCode()
Returns a hash code for this Double object. 
int 
intValue()
Returns the value of this Double as an
int (by casting to type int ). 
boolean 
isInfinite()
Returns true if this Double value is
infinitely large in magnitude, false otherwise. 
static boolean 
isInfinite(double v)
Returns true if the specified number is infinitely
large in magnitude, false otherwise. 
boolean 
isNaN()
Returns true if this Double value is
a NotaNumber (NaN), false otherwise. 
static boolean 
isNaN(double v)
Returns true if the specified number is a
NotaNumber (NaN) value, false otherwise. 
static double 
longBitsToDouble(long bits)
Returns the double value corresponding to a given
bit representation. 
long 
longValue()
Returns the value of this Double as a
long (by casting to type long ). 
static double 
parseDouble(String s)
Returns a new double 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 Double as a
short (by casting to a short ). 
static String 
toHexString(double d)
Returns a hexadecimal string representation of the double argument. 
String 
toString()
Returns a string representation of this Double object. 
static String 
toString(double d)
Returns a string representation of the double
argument. 
static Double 
valueOf(double d)
Returns a Double instance representing the specified double value. 
static Double 
valueOf(String s)
Returns a Double object holding the
double value represented by the argument string
s . 
Methods inherited from class java.lang.Object 

clone, finalize, getClass, notify, notifyAll, wait, wait, wait 
Field Detail 

public static final double POSITIVE_INFINITY
double
. It is equal to the value returned by
Double.longBitsToDouble(0x7ff0000000000000L)
.
public static final double NEGATIVE_INFINITY
double
. It is equal to the value returned by
Double.longBitsToDouble(0xfff0000000000000L)
.
public static final double NaN
double
. It is equivalent to the value returned by
Double.longBitsToDouble(0x7ff8000000000000L)
.
public static final double MAX_VALUE
double
,
(22^{52})·2^{1023}. It is equal to
the hexadecimal floatingpoint literal
0x1.fffffffffffffP+1023
and also equal to
Double.longBitsToDouble(0x7fefffffffffffffL)
.
public static final double MIN_VALUE
double
, 2^{1074}. It is equal to the
hexadecimal floatingpoint literal
0x0.0000000000001P1022
and also equal to
Double.longBitsToDouble(0x1L)
.
public static final int SIZE
public static final Class<Double> TYPE
Class
instance representing the primitive type
double
.
Constructor Detail 

public Double(double value)
Double
object that
represents the primitive double
argument.
value
 the value to be represented by the Double
.public Double(String s) throws NumberFormatException
Double
object that
represents the floatingpoint value of type double
represented by the string. The string is converted to a
double
value as if by the valueOf
method.
s
 a string to be converted to a Double
.
NumberFormatException
 if the string does not contain a
parsable number.valueOf(java.lang.String)
Method Detail 

public static String toString(double d)
double
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)
.
double
. That is, suppose that
x is the exact mathematical value represented by the decimal
representation produced by this method for a finite nonzero argument
d. Then d must be the double
value nearest
to x; or if two double
values are equally close
to x, then d must be one of them and the least
significant bit of the significand of d must be 0
.
To create localized string representations of a floatingpoint
value, use subclasses of NumberFormat
.
d
 the double
to be converted.
public static String toHexString(double d)
double
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"
.
"0x0.0p0"
; thus, negative zero produces the result
"0x0.0p0"
and positive zero produces the result
"0x0.0p0"
.
double
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 Integer.toString
on the
exponent value.
double
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
"p1022"
. Note that there must be at
least one nonzero digit in a subnormal significand.
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 
Double.MAX_VALUE 
0x1.fffffffffffffp1023 
Minimum Normal Value 
0x1.0p1022 
Maximum Subnormal Value 
0x0.fffffffffffffp1022 
Double.MIN_VALUE 
0x0.0000000000001p1022 
d
 the double
to be converted.
public static Double valueOf(String s) throws NumberFormatException
Double
object holding the
double
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 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:
where Sign, FloatingPointLiteral, HexNumeral, HexDigits, SignedInteger and FloatTypeSuffix are as defined in the lexical structure sections of the of the
 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}.
HexDigits0X
HexDigits_{opt}.
HexDigits
 BinaryExponent:
 BinaryExponentIndicator SignedInteger
 BinaryExponentIndicator:
p
P
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 double
by the usual roundtonearest rule of IEEE 754 floatingpoint
arithmetic, which includes preserving the sign of a zero
value. Finally, a Double
object representing this
double
value is returned.
To interpret localized string representations of a
floatingpoint value, use subclasses of 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. The twostep
sequence of conversions, string to float
followed
by float
to double
, is not
equivalent to converting a string directly to
double
. For example, the float
literal 0.1f
is equal to the double
value 0.10000000149011612
; the float
literal 0.1f
represents a different numerical
value than the double
literal
0.1
. (The numerical value 0.1 cannot be exactly
represented in a binary floatingpoint number.)
To avoid calling this method on a invalid string and having
a NumberFormatException
be thrown, the regular
expression below can be used to screen the input string:
final String Digits = "(\\p{Digit}+)";
final String HexDigits = "(\\p{XDigit}+)";
// an exponent is 'e' or 'E' followed by an optionally
// signed decimal integer.
final String Exp = "[eE][+]?"+Digits;
final String fpRegex =
("[\\x00\\x20]*"+ // Optional leading "whitespace"
"[+]?(" + // Optional sign character
"NaN" + // "NaN" string
"Infinity" + // "Infinity" string
// A decimal floatingpoint string representing a finite positive
// number without a leading sign has at most five basic pieces:
// Digits . Digits ExponentPart FloatTypeSuffix
//
// Since this method allows integeronly strings as input
// in addition to strings of floatingpoint literals, the
// two subpatterns below are simplifications of the grammar
// productions from the Java Language Specification, 2nd
// edition, section 3.10.2.
// Digits ._opt Digits_opt ExponentPart_opt FloatTypeSuffix_opt
"((("+Digits+"(\\.)?("+Digits+"?)("+Exp+")?)"+
// . Digits ExponentPart_opt FloatTypeSuffix_opt
"(\\.("+Digits+")("+Exp+")?)"+
// Hexadecimal strings
"((" +
// 0[xX] HexDigits ._opt BinaryExponent FloatTypeSuffix_opt
"(0[xX]" + HexDigits + "(\\.)?)" +
// 0[xX] HexDigits_opt . HexDigits BinaryExponent FloatTypeSuffix_opt
"(0[xX]" + HexDigits + "?(\\.)" + HexDigits + ")" +
")[pP][+]?" + Digits + "))" +
"[fFdD]?))" +
"[\\x00\\x20]*");// Optional trailing "whitespace"
if (Pattern.matches(fpRegex, myString))
Double.valueOf(myString); // Will not throw NumberFormatException
else {
// Perform suitable alternative action
}
s
 the string to be parsed.
Double
object holding the value
represented by the String
argument.
NumberFormatException
 if the string does not contain a
parsable number.public static Double valueOf(double d)
Double(double)
, as this method is likely to yield
significantly better space and time performance by caching
frequently requested values.
d
 a double value.
public static double parseDouble(String s) throws NumberFormatException
double
initialized to the value
represented by the specified String
, as performed
by the valueOf
method of class
Double
.
s
 the string to be parsed.
double
value represented by the string
argument.
NumberFormatException
 if the string does not contain
a parsable double
.valueOf(String)
public static boolean isNaN(double v)
true
if the specified number is a
NotaNumber (NaN) value, false
otherwise.
v
 the value to be tested.
true
if the value of the argument is NaN;
false
otherwise.public static boolean isInfinite(double v)
true
if the specified number is infinitely
large in magnitude, false
otherwise.
v
 the value to be tested.
true
if the value of the argument is positive
infinity or negative infinity; false
otherwise.public boolean isNaN()
true
if this Double
value is
a NotaNumber (NaN), false
otherwise.
true
if the value represented by this object is
NaN; false
otherwise.public boolean isInfinite()
true
if this Double
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()
Double
object.
The primitive double
value represented by this
object is converted to a string exactly as if by the method
toString
of one argument.
toString
in class Object
String
representation of this object.toString(double)
public byte byteValue()
Double
as a byte
(by
casting to a byte
).
byteValue
in class Number
double
value represented by this object
converted to type byte
public short shortValue()
Double
as a
short
(by casting to a short
).
shortValue
in class Number
double
value represented by this object
converted to type short
public int intValue()
Double
as an
int
(by casting to type int
).
intValue
in class Number
double
value represented by this object
converted to type int
public long longValue()
Double
as a
long
(by casting to type long
).
longValue
in class Number
double
value represented by this object
converted to type long
public float floatValue()
float
value of this
Double
object.
floatValue
in class Number
double
value represented by this object
converted to type float
public double doubleValue()
double
value of this
Double
object.
doubleValue
in class Number
double
value represented by this objectpublic int hashCode()
Double
object. The
result is the exclusive OR of the two halves of the
long
integer bit representation, exactly as
produced by the method doubleToLongBits(double)
, of
the primitive double
value represented by this
Double
object. That is, the hash code is the value
of the expression:
where(int)(v^(v>>>32))
v
is defined by:
long v = Double.doubleToLongBits(this.doubleValue());
hashCode
in class Object
hash code
value for this object.Object.equals(java.lang.Object)
,
Hashtable
public boolean equals(Object obj)
true
if and only if the argument is not
null
and is a Double
object that
represents a double
that has the same value as the
double
represented by this object. For this
purpose, two double
values are considered to be
the same if and only if the method doubleToLongBits(double)
returns the identical
long
value when applied to each.
Note that in most cases, for two instances of class
Double
, d1
and d2
, the
value of d1.equals(d2)
is true
if and
only if
d1.doubleValue() == d2.doubleValue()
also has the value true
. However, there are two
exceptions:
d1
and d2
both represent
Double.NaN
, then the equals
method
returns true
, even though
Double.NaN==Double.NaN
has the value
false
.
d1
represents +0.0
while
d2
represents 0.0
, or vice versa,
the equal
test has the value false
,
even though +0.0==0.0
has the value true
.
equals
in class Object
obj
 the object to compare with.
true
if the objects are the same;
false
otherwise.doubleToLongBits(double)
public static long doubleToLongBits(double value)
Bit 63 (the bit that is selected by the mask
0x8000000000000000L
) represents the sign of the
floatingpoint number. Bits
6252 (the bits that are selected by the mask
0x7ff0000000000000L
) represent the exponent. Bits 510
(the bits that are selected by the mask
0x000fffffffffffffL
) represent the significand
(sometimes called the mantissa) of the floatingpoint number.
If the argument is positive infinity, the result is
0x7ff0000000000000L
.
If the argument is negative infinity, the result is
0xfff0000000000000L
.
If the argument is NaN, the result is
0x7ff8000000000000L
.
In all cases, the result is a long
integer that, when
given to the longBitsToDouble(long)
method, will produce a
floatingpoint value the same as the argument to
doubleToLongBits
(except all NaN values are
collapsed to a single "canonical" NaN value).
value
 a double
precision floatingpoint number.
public static long doubleToRawLongBits(double value)
Bit 63 (the bit that is selected by the mask
0x8000000000000000L
) represents the sign of the
floatingpoint number. Bits
6252 (the bits that are selected by the mask
0x7ff0000000000000L
) represent the exponent. Bits 510
(the bits that are selected by the mask
0x000fffffffffffffL
) represent the significand
(sometimes called the mantissa) of the floatingpoint number.
If the argument is positive infinity, the result is
0x7ff0000000000000L
.
If the argument is negative infinity, the result is
0xfff0000000000000L
.
If the argument is NaN, the result is the long
integer representing the actual NaN value. Unlike the
doubleToLongBits
method,
doubleToRawLongBits
does not collapse all the bit
patterns encoding a NaN to a single "canonical" NaN
value.
In all cases, the result is a long
integer that,
when given to the longBitsToDouble(long)
method, will
produce a floatingpoint value the same as the argument to
doubleToRawLongBits
.
value
 a double
precision floatingpoint number.
public static double longBitsToDouble(long bits)
double
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
"double format" bit layout.
If the argument is 0x7ff0000000000000L
, the result
is positive infinity.
If the argument is 0xfff0000000000000L
, the result
is negative infinity.
If the argument is any value in the range
0x7ff0000000000001L
through
0x7fffffffffffffffL
or in the range
0xfff0000000000001L
through
0xffffffffffffffffL
, 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 Double.doubleToRawLongBits
method.
In all other cases, let s, e, and m be three values that can be computed from the argument:
Then the floatingpoint result equals the value of the mathematical expression s·m·2^{e1075}.int s = ((bits >> 63) == 0) ? 1 : 1; int e = (int)((bits >> 52) & 0x7ffL); long m = (e == 0) ? (bits & 0xfffffffffffffL) << 1 : (bits & 0xfffffffffffffL)  0x10000000000000L;
Note that this method may not be able to return a
double
NaN with exactly same bit pattern as the
long
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 longBitsToDouble
may not be able to return a double
with a
signaling NaN bit pattern. Consequently, for some
long
values,
doubleToRawLongBits(longBitsToDouble(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
 any long
integer.
double
floatingpoint value with the same
bit pattern.public int compareTo(Double anotherDouble)
Double
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 double
values:
Double.NaN
is considered by this method
to be equal to itself and greater than all other
double
values (including
Double.POSITIVE_INFINITY
).
0.0d
is considered by this method to be greater
than 0.0d
.
compareTo
in interface Comparable<Double>
anotherDouble
 the Double
to be compared.
0
if anotherDouble
is
numerically equal to this Double
; a value
less than 0
if this Double
is numerically less than anotherDouble
;
and a value greater than 0
if this
Double
is numerically greater than
anotherDouble
.public static int compare(double d1, double d2)
double
values. The sign
of the integer value returned is the same as that of the
integer that would be returned by the call:
new Double(d1).compareTo(new Double(d2))
d1
 the first double
to compared2
 the second double
to compare
0
if d1
is
numerically equal to d2
; a value less than
0
if d1
is numerically less than
d2
; and a value greater than 0
if d1
is numerically greater than
d2
.

Java^{TM} 2 Platform Standard Ed. 5.0 

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