java.lang
Class Double

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

public final class Double

extends Number

Instances of class Double represent primitive double values. Additionally, this class provides various helper functions and variables related to doubles.

Since:

1.0

Field Summary

static double	MAX_VALUE The maximum positive value a double may represent is 1.7976931348623157e+308.
static double	MIN_VALUE The minimum positive value a double may represent is 5e-324.
static double	NaN All IEEE 754 values of NaN have the same value in Java.
static double	NEGATIVE_INFINITY The value of a double representation -1.0/0.0, negative infinity.
static double	POSITIVE_INFINITY The value of a double representing 1.0/0.0, positive infinity.
static Class	TYPE The primitive type double is represented by this Class object.

Constructor Summary

Double(double value)
Create a Double from the primitive double specified.

Double(String s)
Create a Double from the specified String.

Method Summary

byte	byteValue() Return the value of this Double as a byte.
static long	doubleToLongBits(double value) Convert the double to the IEEE 754 floating-point "double format" bit layout.
static long	doubleToRawLongBits(double value) Convert the double to the IEEE 754 floating-point "double format" bit layout.
double	doubleValue() Return the value of this Double.
boolean	equals(Object obj) Returns true if obj is an instance of Double and represents the same double value.
float	floatValue() Return the value of this Double as a float.
int	hashCode() Return a hashcode representing this Object.
int	intValue() Return the value of this Double as an int.
boolean	isInfinite() Return true if the value of this Double is the same as NEGATIVE_INFINITY or POSITIVE_INFINITY, otherwise return false.
static boolean	isInfinite(double v) Return true if the double has a value equal to either NEGATIVE_INFINITY or POSITIVE_INFINITY, otherwise return false.
boolean	isNaN() Return true if the value of this Double is the same as NaN, otherwise return false.
static boolean	isNaN(double v) Return true if the double has the same value as NaN, otherwise return false.
static double	longBitsToDouble(long bits) Convert the argument in IEEE 754 floating-point "double format" bit layout to the corresponding float.
long	longValue() Return the value of this Double as a long.
static double	parseDouble(String s) Parse the specified String as a double.
short	shortValue() Return the value of this Double as a short.
String	toString() Convert the double value of this Double to a String.
static String	toString(double d) Convert the double to a String.
static Double	valueOf(String s) Create a new Double object using the String.

Methods inherited from class java.lang.Object

clone, finalize, getClass

Field Detail

MAX_VALUE

public static final double MAX_VALUE

The maximum positive value a double may represent is 1.7976931348623157e+308.

See Also:

Constant Field Values

MIN_VALUE

public static final double MIN_VALUE

The minimum positive value a double may represent is 5e-324.

See Also:

Constant Field Values

NEGATIVE_INFINITY

public static final double NEGATIVE_INFINITY

The value of a double representation -1.0/0.0, negative infinity.

See Also:

Constant Field Values

POSITIVE_INFINITY

public static final double POSITIVE_INFINITY

The value of a double representing 1.0/0.0, positive infinity.

See Also:

Constant Field Values

NaN

public static final double NaN

All IEEE 754 values of NaN have the same value in Java.

See Also:

Constant Field Values

TYPE

public static final Class TYPE

The primitive type double is represented by this Class object.

Since:

1.1

Constructor Detail

Double

public Double(double value)

Create a Double from the primitive double specified.

Parameters:

value - the double argument

Double

public Double(String s)

Create a Double from the specified String. This method calls Double.parseDouble().

Parameters:

s - the String to convert

Throws:

NumberFormatException - if s cannot be parsed as a double

NullPointerException - if s is null

See Also:

parseDouble(String)

Method Detail

toString

public static String toString(double d)

Convert the double to a String. Floating-point string representation is fairly complex: here is a rundown of the possible values. "[-]" indicates that a negative sign will be printed if the value (or exponent) is negative. "<number>" means a string of digits ('0' to '9'). "<digit>" means a single digit ('0' to '9').

Value of Double	String Representation
[+-] 0	[-]0.0
Between [+-] 10-3 and 107, exclusive	[-]number.number
Other numeric value	[-]<digit>.<number> E[-]<number>
[+-] infinity	[-]Infinity
NaN	NaN

Yes, negative zero is a possible value. Note that there is always a . and at least one digit printed after it: even if the number is 3, it will be printed as 3.0. After the ".", all digits will be printed except trailing zeros. The result is rounded to the shortest decimal number which will parse back to the same double.

To create other output formats, use java.text.NumberFormat.

Parameters:

d - the double to convert

Returns:

the String representing the double

valueOf

public static Double valueOf(String s)

Create a new Double object using the String.

Parameters:

s - the String to convert

Returns:

the new Double

Throws:

NumberFormatException - if s cannot be parsed as a double

NullPointerException - if s is null.

See Also:

parseDouble(String)

parseDouble

public static double parseDouble(String s)

Parse the specified String as a double. The extended BNF grammar is as follows:

 DecodableString:
      ( [ - | + ] NaN )
    | ( [ - | + ] Infinity )
    | ( [ - | + ] FloatingPoint
              [ f | F | d
                | D] )
 FloatingPoint:
      ( { Digit }+ [ . { Digit } ]
              [ Exponent ] )
    | ( . { Digit }+ [ Exponent ] )
 Exponent:
      ( ( e | E )
              [ - | + ] { Digit }+ )
 Digit: '0' through '9'
 

NaN and infinity are special cases, to allow parsing of the output of toString. Otherwise, the result is determined by calculating n * 10^exponent to infinite precision, then rounding to the nearest double. Remember that many numbers cannot be precisely represented in floating point. In case of overflow, infinity is used, and in case of underflow, signed zero is used. Unlike Integer.parseInt, this does not accept Unicode digits outside the ASCII range.

If an unexpected character is found in the String, a NumberFormatException will be thrown. Leading and trailing 'whitespace' is ignored via String.trim(), but spaces internal to the actual number are not allowed.

To parse numbers according to another format, consider using java.text.NumberFormat.

Returns:

the double value of s

Throws:

NumberFormatException - if s cannot be parsed as a double

NullPointerException - if s is null

Since:

1.2

See Also:

MIN_VALUE, MAX_VALUE, POSITIVE_INFINITY, NEGATIVE_INFINITY

isNaN

public static boolean isNaN(double v)

Return true if the double has the same value as NaN, otherwise return false.

Parameters:

v - the double to compare

Returns:

whether the argument is NaN.

isInfinite

public static boolean isInfinite(double v)

Return true if the double has a value equal to either NEGATIVE_INFINITY or POSITIVE_INFINITY, otherwise return false.

Parameters:

v - the double to compare

Returns:

whether the argument is (-/+) infinity.

isNaN

public boolean isNaN()

Return true if the value of this Double is the same as NaN, otherwise return false.

Returns:

whether this Double is NaN

isInfinite

public boolean isInfinite()

Return true if the value of this Double is the same as NEGATIVE_INFINITY or POSITIVE_INFINITY, otherwise return false.

Returns:

whether this Double is (-/+) infinity

toString

public String toString()

Convert the double value of this Double to a String. This method calls Double.toString(double) to do its dirty work.

Overrides:

toString in class Object

Returns:

the String representation

See Also:

toString(double)

byteValue

public byte byteValue()

Return the value of this Double as a byte.

Overrides:

byteValue in class Number

Returns:

the byte value

Since:

1.1

shortValue

public short shortValue()

Return the value of this Double as a short.

Overrides:

shortValue in class Number

Returns:

the short value

Since:

1.1

intValue

public int intValue()

Return the value of this Double as an int.

Specified by:

intValue in class Number

Returns:

the int value

longValue

public long longValue()

Return the value of this Double as a long.

Specified by:

longValue in class Number

Returns:

the long value

floatValue

public float floatValue()

Return the value of this Double as a float.

Specified by:

floatValue in class Number

Returns:

the float value

doubleValue

public double doubleValue()

Return the value of this Double.

Specified by:

doubleValue in class Number

Returns:

the double value

hashCode

public int hashCode()

Return a hashcode representing this Object. Double's hash code is calculated by:
long v = Double.doubleToLongBits(doubleValue());
int hash = (int)(v^(v>>32)).

Overrides:

hashCode in class Object

Returns:

this Object's hash code

See Also:

doubleToLongBits(double)

equals

public boolean equals(Object obj)

Returns true if obj is an instance of Double and represents the same double value. Unlike comparing two doubles with ==, this treats two instances of Double.NaN as equal, but treats 0.0 and -0.0 as unequal.

Note that d1.equals(d2) is identical to doubleToLongBits(d1.doubleValue()) == doubleToLongBits(d2.doubleValue()).

Overrides:

equals in class Object

Parameters:

obj - the object to compare

Returns:

whether the objects are semantically equal

doubleToLongBits

public static long doubleToLongBits(double value)

Convert the double to the IEEE 754 floating-point "double format" bit layout. Bit 63 (the most significant) is the sign bit, bits 62-52 (masked by 0x7ff0000000000000L) represent the exponent, and bits 51-0 (masked by 0x000fffffffffffffL) are the mantissa. This function collapses all versions of NaN to 0x7ff8000000000000L. The result of this function can be used as the argument to Double.longBitsToDouble(long) to obtain the original double value.

Parameters:

value - the double to convert

Returns:

the bits of the double

See Also:

longBitsToDouble(long)

doubleToRawLongBits

public static long doubleToRawLongBits(double value)

Convert the double to the IEEE 754 floating-point "double format" bit layout. Bit 63 (the most significant) is the sign bit, bits 62-52 (masked by 0x7ff0000000000000L) represent the exponent, and bits 51-0 (masked by 0x000fffffffffffffL) are the mantissa. This function leaves NaN alone, rather than collapsing to a canonical value. The result of this function can be used as the argument to Double.longBitsToDouble(long) to obtain the original double value.

Parameters:

value - the double to convert

Returns:

the bits of the double

See Also:

longBitsToDouble(long)

longBitsToDouble

public static double longBitsToDouble(long bits)

Convert the argument in IEEE 754 floating-point "double format" bit layout to the corresponding float. Bit 63 (the most significant) is the sign bit, bits 62-52 (masked by 0x7ff0000000000000L) represent the exponent, and bits 51-0 (masked by 0x000fffffffffffffL) are the mantissa. This function leaves NaN alone, so that you can recover the bit pattern with Double.doubleToRawLongBits(double).

Parameters:

bits - the bits to convert

Returns:

the double represented by the bits

See Also:

doubleToLongBits(double), doubleToRawLongBits(double)