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## java.lang
Class Double

    java.lang.Object
      java.lang.Double

public final class Double
extends Object

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`.

Since:
  JDK1.0, CLDC 1.1

Field Summary
`static double` | `MAX_VALUE` The largest positive finite value of type `double`.
`static double` | `MIN_VALUE` The smallest positive value of type `double`.
`static double` | `NaN` A Not-a-Number (NaN) value of type `double`.
`static double` | `NEGATIVE_INFINITY` The negative infinity of type `double`.
`static double` | `POSITIVE_INFINITY` The positive infinity of type `double`.

Constructor Summary
`Double(double value)` 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.
`boolean` | `equals(Object obj)` Compares this object against the specified object.
`float` | `floatValue()` Returns the float value of this Double.
`int` | `hashCode()` Returns a hashcode for this `Double` object.
`int` | `intValue()` Returns the integer value of this Double (by casting to an int).
`boolean` | `isInfinite()` Returns true if this Double value is infinitely large in magnitude.
`static boolean` | `isInfinite(double v)` 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 v)` Returns true if the specified number is the special Not-a-Number (NaN) value.
`static double` | `longBitsToDouble(long bits)` Returns the double-float corresponding to a given bit representation.
`long` | `longValue()` Returns the long value of this Double (by casting to a 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

  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

  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 Not-a-Number (NaN) value of type `double`. It is equal to the value returned by `Double.longBitsToDouble(0x7ff8000000000000L)`.

  See Also:
    Constant Field Values

### MAX_VALUE

    public static final double MAX_VALUE

  The largest positive finite value of type `double`. It is equal to the value returned by

  >      Double.longBitsToDouble(0x7fefffffffffffffL)

  See Also:
    Constant Field Values

### MIN_VALUE

    public static final double MIN_VALUE

  The smallest positive value of type `double`. It is equal to the value returned by `Double.longBitsToDouble(0x1L)`.

  See Also:
    Constant Field Values

Constructor Detail

### Double

    public Double(double value)

  Constructs a newly allocated `Double` object that represents the primitive `double` argument.

Parameters:
  `value` - the value to be represented by the `Double`.

Method Detail

### toString

    public static String toString(double d)

  Creates 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 '`-`' ('`-`'); 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 107, then it is represented as the integer part of m, in decimal form with no leading zeroes, followed by `'.'` (`.`), followed by one or more decimal digits representing the fractional part of m.
  - If m is less than 10-3 or not less than 107, then it is represented in so-called "computerized scientific notation." Let n be the unique integer such that 10n<=m<10n+1; then let a be the mathematically exact quotient of m and 10n so that 1<=a<10. The magnitude is then represented as the integer part of a, as a single decimal digit, followed by `'.'` (`.`), followed by decimal digits representing the fractional part of a, followed by the letter `'E'` (`E`), followed by a representation of n as a decimal integer, as produced by the method `Integer.toString(int)`.

  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.

### 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)`

### isNaN

    public static boolean isNaN(double v)

  Returns true if the specified number is the special Not-a-Number (NaN) value.

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

### isInfinite

    public static boolean isInfinite(double v)

  Returns true if the specified number is infinitely large in magnitude.

  Parameters:
    `v` - 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.

### 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)`

### byteValue

    public byte byteValue()

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

  Since:
    JDK1.1

### shortValue

    public short shortValue()

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

  Since:
    JDK1.1

### intValue

    public int intValue()

  Returns the integer value of this Double (by casting to an int).

  Returns:
    the `double` value represented by this object is converted to type `int` and the result of the conversion is returned.

### longValue

    public long longValue()

  Returns the long value of this Double (by casting to a long).

  Returns:
    the `double` value represented by this object is converted to type `long` and the result of the conversion is returned.

### floatValue

    public float floatValue()

  Returns the float value of this Double.

  Returns:
    the `double` value represented by this object is converted to type `float` and the result of the conversion is returned.
  Since:
    JDK1.0

### doubleValue

    public double doubleValue()

  Returns the double value of this Double.

  Returns:
    the `double` value represented by this object.

### 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:

  - If `d1` and `d2` both represent `Double.NaN`, then the `equals` method returns `true`, even though `Double.NaN==Double.NaN` has the value `false`.
  - If `d1` represents `+0.0` while `d2` represents `-0.0`, or vice versa, the `equals` test has the value `false`, even though `+0.0==-0.0` has the value `true`. This allows hashtables to operate properly.

  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`

### 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.

  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 equal to the argument to `doubleToLongBits`.

  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-float 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 precision" bit layout. That floating-point value is returned as the result.

  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 NaN. All IEEE 754 NaN values of type `double` are, in effect, lumped together by the Java programming language into a single value called NaN.

  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;

  Then the floating-point result equals the value of the mathematical expression s·m·2e-1075.

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

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