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java.lang
Class Double
java.lang.Object
java.lang.Number
java.lang.Double

All Implemented Interfaces:

Comparable
,
Serializable

public final class
Double

extends
Number

implements
Comparable
<
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.

Since:

JDK1.0

See Also:

Serialized Form
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

TYPE
The Class instance representing the primitive type double.

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. 
int

compareTo
(
Object
Compares this Double object to another object.

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. 
POSITIVE_INFINITY
public static final double POSITIVE_INFINITY

A constant holding the positive infinity of type double. It is equal to the value returned by Double.longBitsToDouble(0x7ff0000000000000L).

See Also:

Constant Field Values
NEGATIVE_INFINITY
public static final double NEGATIVE_INFINITY

A constant holding the negative infinity of type double. It is equal to the value returned by Double.longBitsToDouble(0xfff0000000000000L).

See Also:

Constant Field Values
NaN
public static final double NaN

A constant holding a NotaNumber (NaN) value of type double. It is equivalent to the value returned by Double.longBitsToDouble(0x7ff8000000000000L).

See Also:

Constant Field Values
MAX_VALUE
public static final double MAX_VALUE

A constant holding the largest positive finite value of type double, (22^{
52}
)·2^{
1023}
. It is equal to the
hexadecimal floatingpoint literal 0x1.fffffffffffffP+1023 and also equal to
value returned by:
Double.longBitsToDouble(0x7fefffffffffffffL).

See Also:

Constant Field Values
MIN_VALUE
public static final double MIN_VALUE

A constant holding the smallest positive nonzero value of type double, 2^{
1074}
. It is equal to the
hexadecimal floatingpoint literal 0x0.0000000000001P1022 and also equal to
value returned by
Double.longBitsToDouble(0x1L).

See Also:

Constant Field Values
SIZE
public static final int SIZE

The number of bits used to represent a
double
value.

Since:

1.5

See Also:

Constant Field Values
TYPE
public static final Class< Double> TYPE

The Class instance representing the primitive type double.

Since:

JDK1.1
Double
public Double(double value)

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

Parameters:

value  the value to be represented by the Double.
Double
public Double(String s)
throws NumberFormatException

Constructs a newly allocated 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.

Parameters:

s  a string to be converted to a Double.

Throws:

NumberFormatException
 if the string does not contain a parsable number.

See Also:

valueOf(java.lang.String)
toString
public static String toString(double d)

Returns a string representation of the double 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
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 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
.



Parameters:

d  the double to be converted.

Returns:

a string representation of the argument.
toHexString
public static StringtoHexString (double d)

Returns a hexadecimal string representation of the double 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 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 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.

If
m
is a 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.
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

Double.MAX_VALUE

0x1.fffffffffffffp1023

Minimum Normal Value

0x1.0p1022

Maximum Subnormal Value

0x0.fffffffffffffp1022

Double.MIN_VALUE

0x0.0000000000001p1022




Parameters:

d  the double to be converted.

Returns:

a hex string representation of the argument.

Since:

1.5
valueOf
public static Double valueOf(String s)
throws NumberFormatException

Returns a 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:
rule:

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
,
and
FloatingPointLiteral
,
HexNumeral
,
HexDigits
,
SignedInteger
and
FloatTypeSuffix
are as defined in the lexical structure sections of the of the
Java Language Specification
are as defined in
§3.10.2
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
"computerized
scientific
notation" or as an exact hexadecimal value;
notation";
this exact
numerical
decimal
value is then conceptually converted to an
"infinitely precise"
"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
}



Parameters:

s  the string to be parsed.

Returns:

a Double object holding the value represented by the String argument.

Throws:

NumberFormatException
 if the string does not contain a parsable number.
valueOf
parseDouble
public static Doubledouble valueOf parseDouble (double d) ( String s)
throws NumberFormatException

Returns a
Double
instance representing the specified
double
value. If a new
Double
instance is not required, this method should generally be used in preference to the constructor
Double(double)
, as this method is likely to to yield significantly better space and time performance by cacheing frequently requested values.
Returns a new double initialized to the value represented by the specified String, as performed by the valueOf method of class Double.



Parameters:

d  a double value.
s  the string to be parsed.

Returns:

a
Double
instance representing
d
.
the double value represented by the string argument.

Throws:

NumberFormatException
 if the string does not contain a parsable double.

Since:

1.5
1.2

See Also:

valueOf(String)
parseDouble
isNaN
public static double boolean parseDouble isNaN ( String s)
throws NumberFormatException(double v)

Returns a new double initialized to the value represented by the specified String, as performed by the valueOf method of class Double.
Returns true if the specified number is a NotaNumber (NaN) value, false otherwise.



Parameters:

s
v
 the
string
value
to be
parsed.
tested.

Returns:

the double value represented by the string argument.

Throws:

NumberFormatException
 if the string does not contain a parsable double.

Since:

1.2

See Also:

valueOf(String)
true if the value of the argument is NaN; false otherwise.
isNaN
isInfinite
public static boolean isNaN isInfinite (double v)

Returns true if the specified number is
a NotaNumber (NaN) value,
infinitely large in magnitude,
false otherwise.



Parameters:

v  the value to be tested.

Returns:

true if the value of the argument is
NaN;
positive infinity or negative infinity;
false otherwise.
isInfinite
isNaN
public static boolean isInfinite isNaN (double v) ()

Returns true if the specified number is infinitely large in magnitude, false otherwise.
Returns true if this Double value is a NotaNumber (NaN), false otherwise.



Parameters:

v  the value to be tested.

Returns:

true if the value
of the argument
represented by this object
is
positive infinity or negative infinity;
NaN;
false otherwise.
isNaN
isInfinite
public boolean isNaN isInfinite ()

Returns true if this Double value is
a NotaNumber (NaN),
infinitely large in magnitude,
false otherwise.



Returns:

true if the value represented by this object is
NaN;
positive infinity or negative infinity;
false otherwise.
isInfinite
toString
public boolean
public StringisInfinite toString ()

Returns true if this Double value is infinitely large in magnitude, false otherwise.
Returns a string representation of this 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.


Overrides:

toString
in class
Object


Returns:

true if the value represented by this object is positive infinity or negative infinity; false otherwise.
a String representation of this object.

See Also:

toString(double)
toString
byteValue
public String
public byte toString byteValue ()

Returns a string representation of this 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.
Returns the value of this Double as a byte (by casting to a byte).


Overrides:

toString
byteValue
in class
Object
Number


Returns:

a String representation of this object.
the double value represented by this object converted to type byte

See Also:
Since:

toString(double)
JDK1.1
byteValue
shortValue
public byte short byteValue shortValue ()

Returns the value of this Double as a
byte
short
(by casting to a
byte).
short).


Overrides:

byteValue
shortValue
in class
Number


Returns:

the double value represented by this object converted to type
byte
short

Since:

JDK1.1
shortValue
intValue
public short int shortValue intValue ()

Returns the value of this Double as
a short
an int
(by casting to
a short).
type int).


Overrides:
Specified by:

shortValue
intValue
in class
Number


Returns:

the double value represented by this object converted to type
short

Since:

JDK1.1
int
intValue
longValue
public int long intValue longValue ()

Returns the value of this Double as
an int
a long
(by casting to type
int).
long).


Specified by:

intValue
longValue
in class
Number


Returns:

the double value represented by this object converted to type
int
long
longValue
floatValue
public long float longValue floatValue ()

Returns the
float
value of this Double
as a long (by casting to type long).
object.


Specified by:

longValue
floatValue
in class
Number


Returns:

the double value represented by this object converted to type
long
float

Since:

JDK1.0
floatValue
doubleValue
public float double floatValue doubleValue ()

Returns the
float
double
value of this Double object.


Specified by:

floatValue
doubleValue
in class
Number


Returns:

the double value represented by this object
converted to type float

Since:

JDK1.0
doubleValue
hashCode
public double int doubleValue hashCode ()

Returns the double value of this Double object.
Returns a hash code for this 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:
(int)(v^(v>>>32))
where v is defined by:
long v = Double.doubleToLongBits(this.doubleValue());


Specified by:
Overrides:

doubleValue
hashCode
in class
Number
Object


Returns:

the double value represented by this object
a hash code value for this object.

See Also:

Object.equals(java.lang.Object)
,
Hashtable
hashCode
equals
public int boolean hashCode equals () ( Object obj)

Returns a hash code for this 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)
Compares this object against the specified object. The result is 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)
, of the primitive double value represented by this Double object. That is, the hash code is the value of the expression:
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
(int)(v^(v>>>32))
d1.doubleValue() == d2.doubleValue()
where v is defined by:
long v = Double.doubleToLongBits(this.doubleValue());
also has the value true. However, there are two exceptions:

If d1 and d2 both represent Double.NaN, then the equals method returns true, even though Double.NaN==Double.NaN has the value false.

If 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.
This definition allows hash tables to operate properly.


Overrides:

hashCode
equals
in class
Object


Parameters:

obj  the object to compare with.

Returns:

a hash code value for this object.
true if the objects are the same; false otherwise.

See Also:

Object.equals(java.lang.Object)
doubleToLongBits(double)
,
Hashtable
equals
doubleToLongBits
public boolean
public static long equals doubleToLongBits ( Object obj) (double value)

Compares this object against the specified object. The result is 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.
Returns a representation of the specified floatingpoint value according to the IEEE 754 floatingpoint "double format" bit layout.
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()
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.
also has the value true. However, there are two exceptions:

If d1 and d2 both represent Double.NaN, then the equals method returns true, even though Double.NaN==Double.NaN has the value false.

If 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.
This definition allows hash tables to operate properly.
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).


Overrides:

equals
in class
Object


Parameters:

obj  the object to compare with.
value  a double precision floatingpoint number.

Returns:

true if the objects are the same; false otherwise.

See Also:

doubleToLongBits(double)
the bits that represent the floatingpoint number.
doubleToLongBits
doubleToRawLongBits
public static long doubleToLongBits doubleToRawLongBits (double value)

Returns a representation of the specified floatingpoint value according to the IEEE 754 floatingpoint "double format" bit
layout.
layout, preserving NotaNumber (NaN) values.
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.
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
doubleToLongBits (except all NaN values are collapsed to a single "canonical" NaN value).
doubleToRawLongBits.



Parameters:

value  a double precision floatingpoint number.

Returns:

the bits that represent the floatingpoint number.
doubleToRawLongBits
longBitsToDouble
public static long double doubleToRawLongBits longBitsToDouble (double value) (long bits)

Returns
the double value corresponding to
a
given bit representation. The argument is considered to be a
representation of
the specified
a
floatingpoint value according to the IEEE 754 floatingpoint "double format" bit
layout, preserving NotaNumber (NaN) values.
layout.
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 0x7ff0000000000000L, the result is positive infinity.
If the argument is
positive infinity,
0xfff0000000000000L,
the result is
0x7ff0000000000000L.
negative infinity.
If the argument is negative infinity, the result is 0xfff0000000000000L.
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.
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 other cases, let
s
,
e
, and
m
be three values that can be computed from the argument:
int s = ((bits >> 63) == 0) ? 1 : 1;
int e = (int)((bits >> 52) & 0x7ffL);
long m = (e == 0) ?
(bits & 0xfffffffffffffL) << 1 :
(bits & 0xfffffffffffffL)  0x10000000000000L;
Then the floatingpoint result equals the value of the mathematical expression
s
·
m
·2
^{
e
1075
}
.
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.
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.



Parameters:

value  a double precision floatingpoint number.
bits  any long integer.

Returns:

the bits that represent the floatingpoint number.
the double floatingpoint value with the same bit pattern.
longBitsToDouble
compareTo
public static double
public int longBitsToDouble compareTo (long bits) ( Double anotherDouble)

Returns the 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
Compares two 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.
This ensures that Double.compareTo(Object) (which forwards its behavior to this method) obeys the general contract for Comparable.compareTo, and that the
s
natural order
,
on Doubles is
e
consistent with equals
, and
m
be three values that can be computed from the argument:
int s = ((bits >> 63) == 0) ? 1 : 1;
int e = (int)((bits >> 52) & 0x7ffL);
long m = (e == 0) ?
(bits & 0xfffffffffffffL) << 1 :
(bits & 0xfffffffffffffL)  0x10000000000000L;
Then the floatingpoint result equals the value of the mathematical expression
s
·
m
·2
^{
e
1075
}
.
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.



Parameters:

bits  any long integer.
anotherDouble  the Double to be compared.

Returns:

the double floatingpoint value with the same bit pattern.
the value 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.

Since:

1.2

See Also:

Comparable.compareTo(Object)
compareTo
public int compareTo( DoubleObject anotherDouble) o)

Compares two 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.
This ensures that the
natural ordering
of
Double
objects imposed by this method is
consistent with equals
.
Compares this Double object to another object. If the object is a Double, this function behaves like compareTo(Double). Otherwise, it throws a ClassCastException (as Double objects are comparable only to other Double objects).


Specified by:

compareTo
in interface
Comparable


Parameters:

anotherDouble
o
 the
Double
Object
to be compared. 
Returns:

the value 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.
the value 0 if the argument is a Double numerically equal to this Double; a value less than 0 if the argument is a Double numerically greater than this Double; and a value greater than 0 if the argument is a Double numerically less than this Double.

Throws:

ClassCastException  if the argument is not a Double.

Since:

1.2

See Also:

Comparable
compare
public static int compare(double d1,
double d2)

Compares the two specified 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))



Parameters:

d1  the first double to compare

d2  the second double to compare

Returns:

the value 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.

Since:

1.4