public final class Double
extends Number
implements Comparable<Double>
java.lang.Object  
↳  java.lang.Number  
↳  java.lang.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
.
Constants 


int 
BYTES The number of bytes used to represent a 
int 
MAX_EXPONENT Maximum exponent a finite 
double 
MAX_VALUE A constant holding the largest positive finite value of type 
int 
MIN_EXPONENT Minimum exponent a normalized 
double 
MIN_NORMAL A constant holding the smallest positive normal value of type 
double 
MIN_VALUE A constant holding the smallest positive nonzero value of type 
double 
NEGATIVE_INFINITY A constant holding the negative infinity of type 
double 
NaN A constant holding a NotaNumber (NaN) value of type 
double 
POSITIVE_INFINITY A constant holding the positive infinity of type 
int 
SIZE The number of bits used to represent a 
Fields 


public static final Class<Double> 
TYPE The 
Public constructors 


Double(double value) Constructs a newly allocated 

Double(String s) Constructs a newly allocated 
Public methods 


byte 
byteValue() Returns the value of this 
static int 
compare(double d1, double d2) Compares the two specified 
int 
compareTo(Double anotherDouble) Compares two 
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 
boolean 
equals(Object obj) Compares this object against the specified object. 
float 
floatValue() Returns the 
int 
hashCode() Returns a hash code for this 
static int 
hashCode(double value) Returns a hash code for a 
int 
intValue() Returns the value of this 
static boolean 
isFinite(double d) Returns 
boolean 
isInfinite() Returns 
static boolean 
isInfinite(double v) Returns 
static boolean 
isNaN(double v) Returns 
boolean 
isNaN() Returns 
static double 
longBitsToDouble(long bits) Returns the 
long 
longValue() Returns the value of this 
static double 
max(double a, double b) Returns the greater of two 
static double 
min(double a, double b) Returns the smaller of two 
static double 
parseDouble(String s) Returns a new 
short 
shortValue() Returns the value of this 
static double 
sum(double a, double b) Adds two 
static String 
toHexString(double d) Returns a hexadecimal string representation of the 
static String 
toString(double d) Returns a string representation of the 
String 
toString() Returns a string representation of this 
static Double 
valueOf(String s) Returns a 
static Double 
valueOf(double d) Returns a 
Inherited methods 


From class java.lang.Number


From class java.lang.Object


From interface java.lang.Comparable

int BYTES
The number of bytes used to represent a double
value.
Constant Value: 8 (0x00000008)
int MAX_EXPONENT
Maximum exponent a finite double
variable may have. It is equal to the value returned by Math.getExponent(Double.MAX_VALUE)
.
Constant Value: 1023 (0x000003ff)
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 Double.longBitsToDouble(0x7fefffffffffffffL)
.
Constant Value: 1.7976931348623157E308
int MIN_EXPONENT
Minimum exponent a normalized double
variable may have. It is equal to the value returned by Math.getExponent(Double.MIN_NORMAL)
.
Constant Value: 1022 (0xfffffc02)
double MIN_NORMAL
A constant holding the smallest positive normal value of type double
, 2^{1022}. It is equal to the hexadecimal floatingpoint literal 0x1.0p1022
and also equal to Double.longBitsToDouble(0x0010000000000000L)
.
Constant Value: 2.2250738585072014E308
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 Double.longBitsToDouble(0x1L)
.
Constant Value: 4.9E324
double NEGATIVE_INFINITY
A constant holding the negative infinity of type double
. It is equal to the value returned by Double.longBitsToDouble(0xfff0000000000000L)
.
Constant Value: Infinity
double NaN
A constant holding a NotaNumber (NaN) value of type double
. It is equivalent to the value returned by Double.longBitsToDouble(0x7ff8000000000000L)
.
Constant Value: NaN
double POSITIVE_INFINITY
A constant holding the positive infinity of type double
. It is equal to the value returned by Double.longBitsToDouble(0x7ff0000000000000L)
.
Constant Value: Infinity
int SIZE
The number of bits used to represent a double
value.
Constant Value: 64 (0x00000040)
Class<Double> TYPE
The Class
instance representing the primitive type double
.
Double (double value)
Constructs a newly allocated Double
object that represents the primitive double
argument.
Parameters  

value 
double : the value to be represented by the Double . 
Double (String s)
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 
String : a string to be converted to a Double . 
Throws  

NumberFormatException 
if the string does not contain a parsable number. 
See also:
byte byteValue ()
Returns the value of this Double
as a byte
(by casting to a byte
).
Returns  

byte 
the double value represented by this object converted to type byte 
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 
double : the first double to compare 
d2 
double : the second double to compare 
Returns  

int 
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 . 
int compareTo (Double anotherDouble)
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
. Double
objects imposed by this method is
consistent with equals.
Parameters  

anotherDouble 
Double : the Double to be compared. 
Returns  

int 
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 . 
long doubleToLongBits (double value)
Returns a representation of the specified floatingpoint value according to the IEEE 754 floatingpoint "double format" bit 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 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).
Parameters  

value 
double : a double precision floatingpoint number. 
Returns  

long 
the bits that represent the floatingpoint number. 
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.
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
.
Parameters  

value 
double : a double precision floatingpoint number. 
Returns  

long 
the bits that represent the floatingpoint number. 
double doubleValue ()
Returns the double
value of this Double
object.
Returns  

double 
the double value represented by this object 
boolean equals (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 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
. Parameters  

obj 
Object : the object to compare with. 
Returns  

boolean 
true if the objects are the same; false otherwise. 
See also:
float floatValue ()
Returns the float
value of this Double
object.
Returns  

float 
the double value represented by this object converted to type float 
int hashCode ()
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());
Returns  

int 
a hash code value for this object. 
int hashCode (double value)
Returns a hash code for a double
value; compatible with Double.hashCode()
.
Parameters  

value 
double : the value to hash 
Returns  

int 
a hash code value for a double value. 
int intValue ()
Returns the value of this Double
as an int
(by casting to type int
).
Returns  

int 
the double value represented by this object converted to type int 
boolean isFinite (double d)
Returns true
if the argument is a finite floatingpoint value; returns false
otherwise (for NaN and infinity arguments).
Parameters  

d 
double : the double value to be tested 
Returns  

boolean 
true if the argument is a finite floatingpoint value, false otherwise. 
boolean isInfinite ()
Returns true
if this Double
value is infinitely large in magnitude, false
otherwise.
Returns  

boolean 
true if the value represented by this object is positive infinity or negative infinity; false otherwise. 
boolean isInfinite (double v)
Returns true
if the specified number is infinitely large in magnitude, false
otherwise.
Parameters  

v 
double : the value to be tested. 
Returns  

boolean 
true if the value of the argument is positive infinity or negative infinity; false otherwise. 
boolean isNaN (double v)
Returns true
if the specified number is a NotaNumber (NaN) value, false
otherwise.
Parameters  

v 
double : the value to be tested. 
Returns  

boolean 
true if the value of the argument is NaN; false otherwise. 
boolean isNaN ()
Returns true
if this Double
value is a NotaNumber (NaN), false
otherwise.
Returns  

boolean 
true if the value represented by this object is NaN; false otherwise. 
double longBitsToDouble (long bits)
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 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.
Parameters  

bits 
long : any long integer. 
Returns  

double 
the double floatingpoint value with the same bit pattern. 
long longValue ()
Returns the value of this Double
as a long
(by casting to type long
).
Returns  

long 
the double value represented by this object converted to type long 
double max (double a, double b)
Returns the greater of two double
values as if by calling Math.max
.
Parameters  

a 
double : the first operand 
b 
double : the second operand 
Returns  

double 
the greater of a and b 
See also:
double min (double a, double b)
Returns the smaller of two double
values as if by calling Math.min
.
Parameters  

a 
double : the first operand 
b 
double : the second operand 
Returns  

double 
the smaller of a and b . 
See also:
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
.
Parameters  

s 
String : the string to be parsed. 
Returns  

double 
the double value represented by the string argument. 
Throws  

NullPointerException 
if the string is null 
NumberFormatException 
if the string does not contain a parsable double . 
See also:
short shortValue ()
Returns the value of this Double
as a short
(by casting to a short
).
Returns  

short 
the double value represented by this object converted to type short 
double sum (double a, double b)
Adds two double
values together as per the + operator.
Parameters  

a 
double : the first operand 
b 
double : the second operand 
Returns  

double 
the sum of a and b 
See also:
String toHexString (double d)
Returns a hexadecimal string representation of the 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 
Parameters  

d 
double : the double to be converted. 
Returns  

String 
a hex string representation of the argument. 
String toString (double d)
Returns a string representation of the 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 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
.
Parameters  

d 
double : the double to be converted. 
Returns  

String 
a string representation of the argument. 
String toString ()
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  

String 
a String representation of this object. 
See also:
Double valueOf (String s)
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 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 Java™ Language Specification, except that underscores are not accepted between digits. If
 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. Note that the roundtonearest rule also implies overflow and underflow behaviour; if the exact value of
s
is large enough in magnitude (greater than or equal to (
MAX_VALUE
+
ulp(MAX_VALUE)
/2), rounding to
double
will result in an infinity and if the exact value of
s
is small enough in magnitude (less than or equal to
MIN_VALUE
/2), rounding to float will result in a zero. Finally, after rounding 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 an 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 section 3.10.2 of
// The Java™ Language Specification.
// 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 
String : the string to be parsed. 
Returns  

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

NumberFormatException 
if the string does not contain a parsable number. 
Double valueOf (double d)
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 yield significantly better space and time performance by caching frequently requested values.
Parameters  

d 
double : a double value. 
Returns  

Double 
a Double instance representing d . 