Double

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

所有已实现的接口:

Serializable, Comparable<Double>
```
public final class Double
extends Number
implements Comparable<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.

从以下版本开始:

JDK1.0

另请参阅:

序列化表格

字段概要

字段
限定符和类型	字段	说明
`static int`	`BYTES`	The number of bytes used to represent a `double` value.
`static int`	`MAX_EXPONENT`	Maximum exponent a finite `double` variable may have.
`static double`	`MAX_VALUE`	A constant holding the largest positive finite value of type `double`, (2-2^-52)·2¹⁰²³.
`static int`	`MIN_EXPONENT`	Minimum exponent a normalized `double` variable may have.
`static double`	`MIN_NORMAL`	A constant holding the smallest positive normal value of type `double`, 2^-1022.
`static double`	`MIN_VALUE`	A constant holding the smallest positive nonzero value of type `double`, 2^-1074.
`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`.
`static int`	`SIZE`	The number of bits used to represent a `double` value.
`static Class<Double>`	`TYPE`	The `Class` instance representing the primitive type `double`.

构造器概要

构造器
构造器	说明
`Double(double value)`	Constructs a newly allocated `Double` object that represents the primitive `double` argument.
`Double(String s)`	Constructs a newly allocated `Double` object that represents the floating-point value of type `double` represented by the string.

方法概要

所有方法静态方法实例方法具体方法
限定符和类型	方法	说明
`byte`	`byteValue()`	Returns the value of this `Double` as a `byte` after a narrowing primitive conversion.
`static int`	`compare(double d1, double d2)`	Compares the two specified `double` values.
`int`	`compareTo(Double anotherDouble)`	Compares two `Double` objects 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 `double` value of this `Double` object.
`boolean`	`equals(Object obj)`	Compares this object against the specified object.
`float`	`floatValue()`	Returns the value of this `Double` as a `float` after a narrowing primitive conversion.
`int`	`hashCode()`	Returns a hash code for this `Double` object.
`static int`	`hashCode(double value)`	Returns a hash code for a `double` value; compatible with `Double.hashCode()`.
`int`	`intValue()`	Returns the value of this `Double` as an `int` after a narrowing primitive conversion.
`static boolean`	`isFinite(double d)`	Returns `true` if the argument is a finite floating-point value; returns `false` otherwise (for NaN and infinity arguments).
`boolean`	`isInfinite()`	Returns `true` if this `Double` value is infinitely large in magnitude, `false` otherwise.
`static boolean`	`isInfinite(double v)`	Returns `true` if the specified number is infinitely large in magnitude, `false` otherwise.
`boolean`	`isNaN()`	Returns `true` if this `Double` value is a Not-a-Number (NaN), `false` otherwise.
`static boolean`	`isNaN(double v)`	Returns `true` if the specified number is a Not-a-Number (NaN) value, `false` otherwise.
`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` after a narrowing primitive conversion.
`static double`	`max(double a, double b)`	Returns the greater of two `double` values as if by calling `Math#max(double, double)`.
`static double`	`min(double a, double b)`	Returns the smaller of two `double` values as if by calling `Math#min(double, double)`.
`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` after a narrowing primitive conversion.
`static double`	`sum(double a, double b)`	Adds two `double` values together as per the + operator.
`static String`	`toHexString(double d)`	Returns a hexadecimal string representation of the `double` argument.
`String`	`toString()`	Returns a string representation of this `Double` object.
`static String`	`toString(double d)`	Returns a string representation of the `double` argument.
`static Double`	`valueOf(double d)`	Returns a `Double` instance representing the specified `double` value.
`static Double`	`valueOf(String s)`	Returns a `Double` object holding the `double` value represented by the argument string `s`.

从类继承的方法 java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

字段详细资料
- BYTES
```
public static final int BYTES
```
  The number of bytes used to represent a double value.
  
  从以下版本开始:
  
  1.8
  
  另请参阅:
  
  常量字段值
- 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).
  
  从以下版本开始:
  
  1.6
  
  另请参阅:
  
  常量字段值
- MAX_VALUE
```
public static final double MAX_VALUE
```
  A constant holding the largest positive finite value of type double, (2-2^-52)·2¹⁰²³. It is equal to the hexadecimal floating-point literal 0x1.fffffffffffffP+1023 and also equal to Double.longBitsToDouble(0x7fefffffffffffffL).
  
  另请参阅:
  
  常量字段值
- 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).
  
  从以下版本开始:
  
  1.6
  
  另请参阅:
  
  常量字段值
- 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 floating-point literal 0x1.0p-1022 and also equal to Double.longBitsToDouble(0x0010000000000000L).
  
  从以下版本开始:
  
  1.6
  
  另请参阅:
  
  常量字段值
- 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 floating-point literal 0x0.0000000000001P-1022 and also equal to Double.longBitsToDouble(0x1L).
  
  另请参阅:
  
  常量字段值
- 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).
  
  另请参阅:
  
  常量字段值
- 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).
  
  另请参阅:
  
  常量字段值
- 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).
  
  另请参阅:
  
  常量字段值
- SIZE
```
public static final int SIZE
```
  The number of bits used to represent a double value.
  
  从以下版本开始:
  
  1.5
  
  另请参阅:
  
  常量字段值
- TYPE
```
public static final Class<Double> TYPE
```
  The Class instance representing the primitive type double.
  
  从以下版本开始:
  
  JDK1.1

构造器详细资料
- Double
```
public Double(double value)
```
  Constructs a newly allocated Double object that represents the primitive double argument.
  
  参数:
  
  value - the value to be represented by the Double.
- Double
```
public Double(String s)
       throws NumberFormatException
```
  Constructs a newly allocated 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.
  
  参数:
  
  s - a string to be converted to a Double.
  
  抛出:
  
  NumberFormatException - if the string does not contain a parsable number.
  
  另请参阅:
  
  valueOf(java.lang.String)

方法详细资料

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 10⁷, 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 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 '.' ('\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).
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.
To create localized string representations of a floating-point value, use subclasses of NumberFormat.
参数:

d - the double to be converted.

返回:

a string representation of the argument.

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 to Integer#toString(int) 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 "p-1022". Note that there must be at least one nonzero digit in a subnormal significand.

Examples
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`

参数:: d - the double to be converted.
返回:: a hex string representation of the argument.
从以下版本开始:: 1.5

valueOf
```
public static Double valueOf(String s)
                      throws NumberFormatException
```
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:

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 . HexDigits
0X HexDigits_opt . HexDigits

BinaryExponent:
BinaryExponentIndicator SignedInteger

BinaryExponentIndicator:
p
P

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 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. Note that the round-to-nearest 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 + Math#ulp(double)/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 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 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
  }
 
```
参数:

s - the string to be parsed.

返回:

a Double object holding the value represented by the String argument.

抛出:

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.

参数:

d - a double value.

返回:

a Double instance representing d.

从以下版本开始:

1.5

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.

参数:

s - the string to be parsed.

返回:

the double value represented by the string argument.

抛出:

NullPointerException - if the string is null

NumberFormatException - if the string does not contain a parsable double.

从以下版本开始:

1.2

另请参阅:

valueOf(String)

isNaN
```
public static boolean isNaN(double v)
```
Returns true if the specified number is a Not-a-Number (NaN) value, false otherwise.

参数:

v - the value to be tested.

返回:

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, false otherwise.

参数:

v - the value to be tested.

返回:

true if the value of the argument is positive infinity or negative infinity; false otherwise.

isFinite
```
public static boolean isFinite(double d)
```
Returns true if the argument is a finite floating-point value; returns false otherwise (for NaN and infinity arguments).

参数:

d - the double value to be tested

返回:

true if the argument is a finite floating-point value, false otherwise.

从以下版本开始:

1.8

isNaN
```
public boolean isNaN()
```
Returns true if this Double value is a Not-a-Number (NaN), false otherwise.

返回:

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, false otherwise.

返回:

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.

覆盖:

toString 在类中 Object

返回:

a String representation of this object.

另请参阅:

toString(double)

byteValue
```
public byte byteValue()
```
Returns the value of this Double as a byte after a narrowing primitive conversion.

覆盖:

byteValue 在类中 Number

返回:

the double value represented by this object converted to type byte

从以下版本开始:

JDK1.1

shortValue
```
public short shortValue()
```
Returns the value of this Double as a short after a narrowing primitive conversion.

覆盖:

shortValue 在类中 Number

返回:

the double value represented by this object converted to type short

从以下版本开始:

JDK1.1

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

指定者:

intValue 在类中 Number

返回:

the double value represented by this object converted to type int

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

指定者:

longValue 在类中 Number

返回:

the double value represented by this object converted to type long

floatValue
```
public float floatValue()
```
Returns the value of this Double as a float after a narrowing primitive conversion.

指定者:

floatValue 在类中 Number

返回:

the double value represented by this object converted to type float

从以下版本开始:

JDK1.0

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

指定者:

doubleValue 在类中 Number

返回:

the double value represented by this object

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());

覆盖:

hashCode 在类中 Object

返回:

a hash code value for this object.

另请参阅:

Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

hashCode
```
public static int hashCode(double value)
```
Returns a hash code for a double value; compatible with Double.hashCode().

参数:

value - the value to hash

返回:

a hash code value for a double value.

从以下版本开始:

1.8

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 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 equal test has the value false, even though +0.0==-0.0 has the value true.
This definition allows hash tables to operate properly.
覆盖:

equals 在类中 Object

参数:

obj - the object to compare with.

返回:

true if the objects are the same; false otherwise.

另请参阅:

doubleToLongBits(double)

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 the same as the argument to doubleToLongBits (except all NaN values are collapsed to a single "canonical" NaN value).

参数:

value - a double precision floating-point number.

返回:

the bits that represent the floating-point number.

doubleToRawLongBits
```
public 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.
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.

参数:

value - a double precision floating-point number.

返回:

the bits that represent the floating-point number.

从以下版本开始:

1.3

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.
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;
 
```
Then the floating-point result equals the value of the mathematical expression s·m·2^e-1075.
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.
参数:

bits - any long integer.

返回:

the double floating-point value with the same bit pattern.

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 other double values (including Double.POSITIVE_INFINITY).
- 0.0d is considered by this method to be greater than -0.0d.
This ensures that the natural ordering of Double objects imposed by this method is consistent with equals.
指定者:

compareTo 在接口中 Comparable<Double>

参数:

anotherDouble - the Double to be compared.

返回:

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.

从以下版本开始:

1.2

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))
 
```
参数:

d1 - the first double to compare

d2 - the second double to compare

返回:

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.

从以下版本开始:

1.4

sum
```
public static double sum(double a,
                         double b)
```
Adds two double values together as per the + operator.

参数:

a - the first operand

b - the second operand

返回:

the sum of a and b

从以下版本开始:

1.8

另请参阅:

BinaryOperator

max
```
public static double max(double a,
                         double b)
```
Returns the greater of two double values as if by calling Math#max(double, double).

参数:

a - the first operand

b - the second operand

返回:

the greater of a and b

从以下版本开始:

1.8

另请参阅:

BinaryOperator

min
```
public static double min(double a,
                         double b)
```
Returns the smaller of two double values as if by calling Math#min(double, double).

参数:

a - the first operand

b - the second operand

返回:

the smaller of a and b.

从以下版本开始:

1.8

另请参阅:

BinaryOperator

类 Double

字段概要

构造器概要

方法概要

从类继承的方法 java.lang.Object

字段详细资料

BYTES

MAX_EXPONENT

MAX_VALUE

MIN_EXPONENT

MIN_NORMAL

MIN_VALUE

NEGATIVE_INFINITY

NaN

POSITIVE_INFINITY

SIZE

TYPE

构造器详细资料

Double

Double

方法详细资料

toString

toHexString

valueOf

valueOf

parseDouble

isNaN

isInfinite

isFinite

isNaN

isInfinite

toString

byteValue

shortValue

intValue

longValue

floatValue

doubleValue

hashCode

hashCode

equals

doubleToLongBits

doubleToRawLongBits

longBitsToDouble

compareTo

compare

sum

max

min