java.lang
Class Double

java.lang.Object
  extended by java.lang.Number
      extended by java.lang.Double
All Implemented Interfaces:
Serializable

public final class Double
extends Number

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.

See Also:
Serialized Form

Field Summary
static double MAX_VALUE
          A constant holding the largest positive finite value of type double, 1·7976931348623157e+308.
static double MIN_VALUE
          A constant holding the smallest positive nonzero value of type double, 4.94065645841246544e-324.
static double NaN
          A constant holding a Not-a-Number (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.
 
Constructor Summary
Double(double d)
          Constructs a newly allocated Double object that represents the primitive double argument.
 
Method Summary
 byte byteValue()
          Returns the value of this Double as a byte (by casting to a byte).
static long doubleToLongBits(double value)
          Returns a representation of the specified floating-point value according to the IEEE 754 floating-point "double format" bit layout.
 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 hashcode 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.
static boolean isInfinite(double d)
          Returns true if the specified number is infinitely large in magnitude.
 boolean isNaN()
          Returns true if this Double value is the special Not-a-Number (NaN) value.
static boolean isNaN(double d)
          Returns true if the specified number is the special Not-a-Number (NaN) value.
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).
 String toString()
          Returns a String representation of this Double object.
static String toString(double d)
          Creates a string representation of the double argument.
static Double valueOf(String s)
          Returns a new Double object initialized to the value represented by the specified string.
 
Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

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 Not-a-Number (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, 1·7976931348623157e+308. It is equal to the hexadecimal floating-point literal 0x1.0p-1022 and also equal to Double.longBitsToDouble(0x0010000000000000L).

See Also:
Constant Field Values

MIN_VALUE

public static final double MIN_VALUE
A constant holding the smallest positive nonzero value of type double, 4.94065645841246544e-324. It is equal to the hexadecimal floating-point literal 0x0.0000000000001P-1022 and also equal to Double.longBitsToDouble(0x1L).

See Also:
Constant Field Values
Constructor Detail

Double

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

Parameters:
d - the value to be represented by the Double.
Method Detail

doubleToLongBits

public static long doubleToLongBits(double value)
Returns a representation of the specified floating-point value according to the IEEE 754 floating-point "double format" bit layout.

Parameters:
value - a double precision floating-point number.
Returns:
the bits that represent the floating-point number.

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 floating-point value according to the IEEE 754 floating-point "double format" bit layout.

Parameters:
bits - any long integer.
Returns:
the double floating-point value with the same bit pattern.

byteValue

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

Specified by:
byteValue in class Number
Returns:
the double value represented by this object converted to type byte

shortValue

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

Specified by:
shortValue in class Number
Returns:
the double value represented by this object converted to type short

intValue

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

Specified by:
intValue in class Number
Returns:
the double value represented by this object converted to type int

longValue

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

Specified by:
longValue in class Number
Returns:
the double value represented by this object converted to type long

doubleValue

public double doubleValue()
Returns the double value of this Double object.

Specified by:
doubleValue in class Number
Returns:
the double value represented by this object

floatValue

public float floatValue()
Returns the float value of this Double object.

Specified by:
floatValue in class Number
Returns:
the double value represented by this object converted to type float

toString

public static String toString(double d)
Creates a string representation of the double argument. All characters mentioned below are ASCII characters.

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.

Parameters:
d - the double to be converted.
Returns:
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.

Overrides:
toString in class Object
Returns:
a String representation of this object.
See Also:
toString(double)

isNaN

public static boolean isNaN(double d)
Returns true if the specified number is the special Not-a-Number (NaN) value.

Parameters:
d - the value to be tested.
Returns:
true if the value of the argument is NaN; false otherwise.

isInfinite

public static boolean isInfinite(double d)
Returns true if the specified number is infinitely large in magnitude.

Parameters:
d - the value to be tested.
Returns:
true if the value of the argument is positive infinity or negative infinity; false otherwise.

isNaN

public boolean isNaN()
Returns true if this Double value is the special Not-a-Number (NaN) value.

Returns:
true if the value represented by this object is NaN; false otherwise.

isInfinite

public boolean isInfinite()
Returns true if this Double value is infinitely large in magnitude.

Returns:
true if the value represented by this object is positive infinity or negative infinity; false otherwise.

valueOf

public static Double valueOf(String s)
                      throws NumberFormatException
Returns a new Double object initialized to the value represented by the specified string. The string s is interpreted as the representation of a floating-point value and a Double object representing that value is created and returned.

If s is null, then a NullPointerException is thrown.

Leading and trailing whitespace characters in s are ignored. The rest of s should constitute a FloatValue as described by the lexical rule:


 FloatValue:

        Signopt FloatingPointLiteral
 
where Sign and FloatingPointLiteral are as defined in Section 3.10.2 of the Java Language Specification. If it does not have the form of a FloatValue, then a NumberFormatException is thrown. Otherwise, it is regarded as representing an exact decimal value in the usual "computerized scientific notation"; this exact decimal value is then conceptually converted to an "infinitely precise" binary value that is then rounded to type double by the usual round-to-nearest rule of IEEE 754 floating-point arithmetic. Finally, a new object of class Double is created to represent the double value.

Parameters:
s - the string to be parsed.
Returns:
a newly constructed Double initialized to the value represented by the string argument.
Throws:
NumberFormatException - if the string does not contain a parsable number.

parseDouble

public static double parseDouble(String s)
                          throws NumberFormatException
Returns a new double initialized to the value represented by the specified String, as performed by the valueOf method of class Double.

Parameters:
s - the string to be parsed.
Returns:
the double value represented by the string argument.
Throws:
NumberFormatException - if the string does not contain a parsable double.
Since:
JDK1.2
See Also:
valueOf(String)

hashCode

public int hashCode()
Returns a hashcode 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 hashcode is the value of the expression:
 (int)(v^(v>>>32))
 
where v is defined by:
 long v = Double.doubleToLongBits(this.doubleValue());
 

Overrides:
hashCode in class Object
Returns:
a hash code value for this object.
See Also:
Object.equals(java.lang.Object), Hashtable

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 identical bit pattern to the bit pattern of 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 same 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:

Overrides:
equals in class Object
Parameters:
obj - the object to compare with.
Returns:
true if the objects are the same; false otherwise.
See Also:
Boolean.hashCode(), Hashtable


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