Double
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
.
Summary
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 value of this 
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  

Constants
BYTES
public static final int BYTES
The number of bytes used to represent a double
value.
Constant Value: 8 (0x00000008)
MAX_EXPONENT
public static final 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)
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
Double.longBitsToDouble(0x7fefffffffffffffL)
.
Constant Value: 1.7976931348623157E308
MIN_EXPONENT
public static final 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)
MIN_NORMAL
public static final 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
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
Double.longBitsToDouble(0x1L)
.
Constant Value: 4.9E324
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)
.
Constant Value: Infinity
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)
.
Constant Value: NaN
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)
.
Constant Value: Infinity
SIZE
public static final int SIZE
The number of bits used to represent a double
value.
Constant Value: 64 (0x00000040)
Fields
TYPE
public static final Class<Double> TYPE
The Class
instance representing the primitive type
double
.
Public constructors
Double
public 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
public 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:
Public methods
byteValue
public byte byteValue ()
Returns the value of this Double
as a byte
after a narrowing primitive conversion.
Returns  

byte 
the double value represented by this object
converted to type byte 
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 
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 . 
compareTo
public 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 otherdouble
values (includingDouble.POSITIVE_INFINITY
). 
0.0d
is considered by this method to be greater than0.0d
.
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 . 
doubleToLongBits
public static 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. 
doubleToRawLongBits
public 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.
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. 
doubleValue
public double doubleValue ()
Returns the double
value of this Double
object.
Returns  

double 
the double value represented by this object

equals
public 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:
 If
d1
andd2
both representDouble.NaN
, then theequals
method returnstrue
, even thoughDouble.NaN==Double.NaN
has the valuefalse
.  If
d1
represents+0.0
whiled2
represents0.0
, or vice versa, theequal
test has the valuefalse
, even though+0.0==0.0
has the valuetrue
.
Parameters  

obj 
Object : the object to compare with. 
Returns  

boolean 
true if the objects are the same;
false otherwise. 
See also:
floatValue
public float floatValue ()
Returns the value of this Double
as a float
after a narrowing primitive conversion.
Returns  

float 
the double value represented by this object
converted to type float 
hashCode
public 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.

hashCode
public static 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. 
intValue
public int intValue ()
Returns the value of this Double
as an int
after a narrowing primitive conversion.
Returns  

int 
the double value represented by this object
converted to type int

isFinite
public static 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. 
isInfinite
public 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.

isInfinite
public static 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.

isNaN
public static 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.

isNaN
public 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.

longBitsToDouble
public static 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.

longValue
public long longValue ()
Returns the value of this Double
as a long
after a narrowing primitive conversion.
Returns  

long 
the double value represented by this object
converted to type long 
max
public static 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:
min
public static 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:
parseDouble
public 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
.
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:
shortValue
public short shortValue ()
Returns the value of this Double
as a short
after a narrowing primitive conversion.
Returns  

short 
the double value represented by this object
converted to type short 
sum
public static 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:
toHexString
public static String toHexString (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 toInteger.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.
 If m is infinity, it is represented by the string
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. 
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 methodInteger.toString(int)
.
 If m is infinity, it is represented by the characters
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. 
toString
public 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:
valueOf
public static 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 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 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. 
valueOf
public static 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 . 
Annotations
Interfaces
Classes
 Boolean
 Byte
 Character
 Character.Subset
 Character.UnicodeBlock
 Class
 ClassLoader
 Compiler
 Double
 Enum
 Float
 InheritableThreadLocal
 Integer
 Long
 Math
 Number
 Object
 Package
 Process
 ProcessBuilder
 ProcessBuilder.Redirect
 Runtime
 RuntimePermission
 SecurityManager
 Short
 StackTraceElement
 StrictMath
 String
 StringBuffer
 StringBuilder
 System
 Thread
 ThreadGroup
 ThreadLocal
 Throwable
 Void
Enums
Exceptions
 ArithmeticException
 ArrayIndexOutOfBoundsException
 ArrayStoreException
 ClassCastException
 ClassNotFoundException
 CloneNotSupportedException
 EnumConstantNotPresentException
 Exception
 IllegalAccessException
 IllegalArgumentException
 IllegalMonitorStateException
 IllegalStateException
 IllegalThreadStateException
 IndexOutOfBoundsException
 InstantiationException
 InterruptedException
 NegativeArraySizeException
 NoSuchFieldException
 NoSuchMethodException
 NullPointerException
 NumberFormatException
 ReflectiveOperationException
 RuntimeException
 SecurityException
 StringIndexOutOfBoundsException
 TypeNotPresentException
 UnsupportedOperationException
Errors
 AbstractMethodError
 AssertionError
 BootstrapMethodError
 ClassCircularityError
 ClassFormatError
 Error
 ExceptionInInitializerError
 IllegalAccessError
 IncompatibleClassChangeError
 InstantiationError
 InternalError
 LinkageError
 NoClassDefFoundError
 NoSuchFieldError
 NoSuchMethodError
 OutOfMemoryError
 StackOverflowError
 ThreadDeath
 UnknownError
 UnsatisfiedLinkError
 UnsupportedClassVersionError
 VerifyError
 VirtualMachineError