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 | Java™ Platform Standard Ed. 6 | |||||||||
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java.lang.Objectjava.lang.Number
java.lang.Double
public final class 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.
| Field Summary | |
|---|---|
| static int | MAX_EXPONENTMaximum exponent a finite doublevariable may have. | 
| static double | MAX_VALUEA constant holding the largest positive finite value of type double,
 (2-2-52)·21023. | 
| static int | MIN_EXPONENTMinimum exponent a normalized doublevariable may
 have. | 
| static double | MIN_NORMALA constant holding the smallest positive normal value of type double, 2-1022. | 
| static double | MIN_VALUEA constant holding the smallest positive nonzero value of type double, 2-1074. | 
| static double | NaNA constant holding a Not-a-Number (NaN) value of type double. | 
| static double | NEGATIVE_INFINITYA constant holding the negative infinity of type double. | 
| static double | POSITIVE_INFINITYA constant holding the positive infinity of type double. | 
| static int | SIZEThe number of bits used to represent a double value. | 
| static Class<Double> | TYPEThe Classinstance representing the primitive typedouble. | 
| Constructor Summary | |
|---|---|
| Double(double value)Constructs a newly allocated Doubleobject that
 represents the primitivedoubleargument. | |
| Double(String s)Constructs a newly allocated Doubleobject that
 represents the floating-point value of typedoublerepresented by the string. | |
| Method Summary | |
|---|---|
|  byte | byteValue()Returns the value of this Doubleas abyte(by
 casting to abyte). | 
| static int | compare(double d1,
        double d2)Compares the two specified doublevalues. | 
|  int | compareTo(Double anotherDouble)Compares two Doubleobjects numerically. | 
| 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. | 
| static long | doubleToRawLongBits(double value)Returns a representation of the specified floating-point value according to the IEEE 754 floating-point "double format" bit layout, preserving Not-a-Number (NaN) values. | 
|  double | doubleValue()Returns the doublevalue of thisDoubleobject. | 
|  boolean | equals(Object obj)Compares this object against the specified object. | 
|  float | floatValue()Returns the floatvalue of thisDoubleobject. | 
|  int | hashCode()Returns a hash code for this Doubleobject. | 
|  int | intValue()Returns the value of this Doubleas anint(by casting to typeint). | 
|  boolean | isInfinite()Returns trueif thisDoublevalue is
 infinitely large in magnitude,falseotherwise. | 
| static boolean | isInfinite(double v)Returns trueif the specified number is infinitely
 large in magnitude,falseotherwise. | 
|  boolean | isNaN()Returns trueif thisDoublevalue is
 a Not-a-Number (NaN),falseotherwise. | 
| static boolean | isNaN(double v)Returns trueif the specified number is a
 Not-a-Number (NaN) value,falseotherwise. | 
| static double | longBitsToDouble(long bits)Returns the doublevalue corresponding to a given
 bit representation. | 
|  long | longValue()Returns the value of this Doubleas along(by casting to typelong). | 
| static double | parseDouble(String s)Returns a new doubleinitialized to the value
 represented by the specifiedString, as performed
 by thevalueOfmethod of classDouble. | 
|  short | shortValue()Returns the value of this Doubleas ashort(by casting to ashort). | 
| static String | toHexString(double d)Returns a hexadecimal string representation of the doubleargument. | 
|  String | toString()Returns a string representation of this Doubleobject. | 
| static String | toString(double d)Returns a string representation of the doubleargument. | 
| static Double | valueOf(double d)Returns a Double instance representing the specified double value. | 
| static Double | valueOf(String s)Returns a Doubleobject holding thedoublevalue represented by the argument strings. | 
| Methods inherited from class java.lang.Object | 
|---|
| clone, finalize, getClass, notify, notifyAll, wait, wait, wait | 
| Field Detail | 
|---|
public static final double POSITIVE_INFINITY
double. It is equal to the value returned by
 Double.longBitsToDouble(0x7ff0000000000000L).
public static final double NEGATIVE_INFINITY
double. It is equal to the value returned by
 Double.longBitsToDouble(0xfff0000000000000L).
public static final double NaN
double. It is equivalent to the value returned by
 Double.longBitsToDouble(0x7ff8000000000000L).
public static final double MAX_VALUE
double,
 (2-2-52)·21023.  It is equal to
 the hexadecimal floating-point literal
 0x1.fffffffffffffP+1023 and also equal to
 Double.longBitsToDouble(0x7fefffffffffffffL).
public static final double MIN_NORMAL
double, 2-1022.  It is equal to the
 hexadecimal floating-point literal 0x1.0p-1022 and also
 equal to Double.longBitsToDouble(0x0010000000000000L).
public static final double MIN_VALUE
double, 2-1074. It is equal to the
 hexadecimal floating-point literal
 0x0.0000000000001P-1022 and also equal to
 Double.longBitsToDouble(0x1L).
public static final int MAX_EXPONENT
double variable may have.
 It is equal to the value returned by
 Math.getExponent(Double.MAX_VALUE).
public static final int MIN_EXPONENT
double variable may
 have.  It is equal to the value returned by
 Math.getExponent(Double.MIN_NORMAL).
public static final int SIZE
public static final Class<Double> TYPE
Class instance representing the primitive type
 double.
| Constructor Detail | 
|---|
public Double(double value)
Double object that
 represents the primitive double argument.
value - the value to be represented by the Double.
public Double(String s)
       throws NumberFormatException
Double object that
 represents the floating-point value of type double
 represented by the string. The string is converted to a
 double value as if by the valueOf method.
s - a string to be converted to a Double.
NumberFormatException - if the string does not contain a
               parsable number.valueOf(java.lang.String)| Method Detail | 
|---|
public static String toString(double d)
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 Integer.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 floating-point
 value, use subclasses of NumberFormat.
d - the double to be converted.
public static String toHexString(double d)
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
 "p-1022".  Note that there must be at
 least one nonzero digit in a subnormal significand.
 | Floating-point Value | Hexadecimal String | 
|---|---|
| 1.0 | 0x1.0p0 | 
| -1.0 | -0x1.0p0 | 
| 2.0 | 0x1.0p1 | 
| 3.0 | 0x1.8p1 | 
| 0.5 | 0x1.0p-1 | 
| 0.25 | 0x1.0p-2 | 
| Double.MAX_VALUE | 0x1.fffffffffffffp1023 | 
| Minimum Normal Value | 0x1.0p-1022 | 
| Maximum Subnormal Value | 0x0.fffffffffffffp-1022 | 
| Double.MIN_VALUE | 0x0.0000000000001p-1022 | 
d - the double to be converted.
public static Double valueOf(String s)
                      throws NumberFormatException
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 of the Java Language Specification. If
- FloatValue:
- Signopt
NaN- Signopt
Infinity- Signopt FloatingPointLiteral
- Signopt HexFloatingPointLiteral
- SignedInteger
- HexFloatingPointLiteral:
- HexSignificand BinaryExponent FloatTypeSuffixopt
- HexSignificand:
- HexNumeral
- HexNumeral
.
0xHexDigitsopt.HexDigits
0XHexDigitsopt.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 round-to-nearest rule of IEEE 754 floating-point
 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
 floating-point value, use subclasses of NumberFormat.
 
Note that trailing format specifiers, specifiers that
 determine the type of a floating-point 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 floating-point type.  The two-step
 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 floating-point 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 floating-point string representing a finite positive
             // number without a leading sign has at most five basic pieces:
             // Digits . Digits ExponentPart FloatTypeSuffix
             // 
             // Since this method allows integer-only strings as input
             // in addition to strings of floating-point literals, the
             // two sub-patterns 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
        }
 
 
s - the string to be parsed.
Double object holding the value
             represented by the String argument.
NumberFormatException - if the string does not contain a
               parsable number.public static Double valueOf(double d)
Double(double), as this method is likely to yield
 significantly better space and time performance by caching
 frequently requested values.
d - a double value.
public static double parseDouble(String s)
                          throws NumberFormatException
double initialized to the value
 represented by the specified String, as performed
 by the valueOf method of class
 Double.
s - the string to be parsed.
double value represented by the string
         argument.
NumberFormatException - if the string does not contain
            a parsable double.valueOf(String)public static boolean isNaN(double v)
true if the specified number is a
 Not-a-Number (NaN) value, false otherwise.
v - the value to be tested.
true if the value of the argument is NaN;
          false otherwise.public static boolean isInfinite(double v)
true if the specified number is infinitely
 large in magnitude, false otherwise.
v - the value to be tested.
true if the value of the argument is positive
          infinity or negative infinity; false otherwise.public boolean isNaN()
true if this Double value is
 a Not-a-Number (NaN), false otherwise.
true if the value represented by this object is
          NaN; false otherwise.public boolean isInfinite()
true if this Double value is
 infinitely large in magnitude, false otherwise.
true if the value represented by this object is
          positive infinity or negative infinity;
          false otherwise.public String toString()
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.
toString in class ObjectString representation of this object.toString(double)public byte byteValue()
Double as a byte (by
 casting to a byte).
byteValue in class Numberdouble value represented by this object
          converted to type bytepublic short shortValue()
Double as a
 short (by casting to a short).
shortValue in class Numberdouble value represented by this object
          converted to type shortpublic int intValue()
Double as an
 int (by casting to type int).
intValue in class Numberdouble value represented by this object
          converted to type intpublic long longValue()
Double as a
 long (by casting to type long).
longValue in class Numberdouble value represented by this object
          converted to type longpublic float floatValue()
float value of this
 Double object.
floatValue in class Numberdouble value represented by this object
          converted to type floatpublic double doubleValue()
double value of this
 Double object.
doubleValue in class Numberdouble value represented by this objectpublic int hashCode()
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:
 where(int)(v^(v>>>32))
v is defined by: 
 long v = Double.doubleToLongBits(this.doubleValue());
hashCode in class Objecthash code value for this object.Object.equals(java.lang.Object), 
Hashtablepublic boolean equals(Object obj)
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.
 
equals in class Objectobj - the object to compare with.
true if the objects are the same;
          false otherwise.doubleToLongBits(double)public static long doubleToLongBits(double value)
 Bit 63 (the bit that is selected by the mask 
 0x8000000000000000L) represents the sign of the 
 floating-point number. Bits 
 62-52 (the bits that are selected by the mask 
 0x7ff0000000000000L) represent the exponent. Bits 51-0 
 (the bits that are selected by the mask 
 0x000fffffffffffffL) represent the significand 
 (sometimes called the mantissa) of the floating-point 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 
 floating-point value the same as the argument to 
 doubleToLongBits (except all NaN values are
 collapsed to a single "canonical" NaN value).
value - a double precision floating-point number.
public static long doubleToRawLongBits(double value)
 Bit 63 (the bit that is selected by the mask 
 0x8000000000000000L) represents the sign of the 
 floating-point number. Bits 
 62-52 (the bits that are selected by the mask 
 0x7ff0000000000000L) represent the exponent. Bits 51-0 
 (the bits that are selected by the mask 
 0x000fffffffffffffL) represent the significand 
 (sometimes called the mantissa) of the floating-point 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 floating-point value the same as the argument to
 doubleToRawLongBits.
value - a double precision floating-point number.
public static double longBitsToDouble(long bits)
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.
 
 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 floating-point 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:
 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.
bits - any long integer.
double floating-point value with the same
          bit pattern.public int compareTo(Double anotherDouble)
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.
 
compareTo in interface Comparable<Double>anotherDouble - the Double to be compared.
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.
public static int compare(double d1,
                          double d2)
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))
 
d1 - the first double to compared2 - the second double to compare
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.| 
 | Java™ Platform Standard Ed. 6 | |||||||||
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Copyright 2008 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.