Serializable
, Comparable<Double>
, Constable
, ConstantDesc
public final class Double extends Number implements Comparable<Double>, Constable, ConstantDesc
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
.
This is a value-based class; programmers should treat instances that are equal as interchangeable and should not use instances for synchronization, or unpredictable behavior may occur. For example, in a future release, synchronization may fail.
+0.0
and -0.0
), signed infinities (positive infinity and negative infinity), and NaN (not-a-number). An equivalence relation on a set of values is a boolean relation on pairs of values that is reflexive, symmetric, and transitive. For more discussion of equivalence relations and object equality, see the Object.equals
specification. An equivalence relation partitions the values it operates over into sets called equivalence classes. All the members of the equivalence class are equal to each other under the relation. An equivalence class may contain only a single member. At least for some purposes, all the members of an equivalence class are substitutable for each other. In particular, in a numeric expression equivalent values can be substituted for one another without changing the result of the expression, meaning changing the equivalence class of the result of the expression.
Notably, the built-in ==
operation on floating-point values is not an equivalence relation. Despite not defining an equivalence relation, the semantics of the IEEE 754 ==
operator were deliberately designed to meet other needs of numerical computation. There are two exceptions where the properties of an equivalence relation are not satisfied by
==
on floating-point values:
v1
and v2
are both NaN, then v1
== v2
has the value false
. Therefore, for two NaN arguments the reflexive property of an equivalence relation is not satisfied by the ==
operator. v1
represents +0.0
while v2
represents -0.0
, or vice versa, then v1 == v2
has the value true
even though +0.0
and -0.0
are distinguishable under various floating-point operations. For example, 1.0/+0.0
evaluates to positive infinity while 1.0/-0.0
evaluates to negative infinity and positive infinity and negative infinity are neither equal to each other nor equivalent to each other. Thus, while a signed zero input most commonly determines the sign of a zero result, because of dividing by zero, +0.0
and -0.0
may not be substituted for each other in general. The sign of a zero input also has a non-substitutable effect on the result of some math library methods. For ordered comparisons using the built-in comparison operators (<
, <=
, etc.), NaN values have another anomalous situation: a NaN is neither less than, nor greater than, nor equal to any value, including itself. This means the trichotomy of comparison does not hold.
To provide the appropriate semantics for equals
and compareTo
methods, those methods cannot simply be wrappers around ==
or ordered comparison operations. Instead, equals
uses representation equivalence, defining NaN arguments to be equal to each other, restoring reflexivity, and defining +0.0
to not be equal to -0.0
. For comparisons, compareTo
defines a total order where -0.0
is less than +0.0
and where a NaN is equal to itself and considered greater than positive infinity.
The operational semantics of equals
and
compareTo
are expressed in terms of bit-wise converting the floating-point values to integral values.
The natural ordering implemented by compareTo
is consistent with equals. That is, two objects are reported as equal by equals
if and only if compareTo
on those objects returns zero.
The adjusted behaviors defined for equals
and
compareTo
allow instances of wrapper classes to work properly with conventional data structures. For example, defining NaN values to be equals
to one another allows NaN to be used as an element of a HashSet
or as the key of a HashMap
. Similarly, defining
compareTo
as a total ordering, including +0.0
,
-0.0
, and NaN, allows instances of wrapper classes to be used as elements of a SortedSet
or as keys of a SortedMap
.
Comparing numerical equality to various useful equivalence relations that can be defined over floating-point values:
==
operator): (Not an equivalence relation)+0.0
and -0.0
are equal since they both map to the same real value, 0. A NaN does not map to any real number and is not equal to any value, including itself. double
values a
and
b
is implemented by the expression Double.doubleTo
Raw
LongBits(a) == Double.doubleTo
Raw
LongBits(b)
+0.0
and -0.0
are distinguished from each other and every bit pattern encoding a NaN is distinguished from every other bit pattern encoding a NaN. +0.0
and -0.0
are distinguished from each other. Double.doubleToLongBits(a) == Double.doubleToLongBits(b)
Double.valueOf(a).equals(Double.valueOf(b))
Double.compare(a, b) == 0
a
and b
, if neither of a
and b
is zero or NaN, then the three relations numerical equality, bit-wise equivalence, and representation equivalence of a
and b
have the same true
/false
value. In other words, for binary floating-point values, the three relations only differ if at least one argument is zero or NaN.<
, <=
, >
, and >=
Modifier and Type | Field | Description |
---|---|---|
static final int |
BYTES |
The number of bytes used to represent a double value. |
static final int |
MAX_EXPONENT |
Maximum exponent a finite double variable may have. |
static final double |
MAX_VALUE |
A constant holding the largest positive finite value of type double , (2-2-52)·21023. |
static final int |
MIN_EXPONENT |
Minimum exponent a normalized double variable may have. |
static final double |
MIN_NORMAL |
A constant holding the smallest positive normal value of type double , 2-1022. |
static final double |
MIN_VALUE |
A constant holding the smallest positive nonzero value of type double , 2-1074. |
static final double |
NaN |
A constant holding a Not-a-Number (NaN) value of type double . |
static final double |
NEGATIVE_INFINITY |
A constant holding the negative infinity of type double . |
static final double |
POSITIVE_INFINITY |
A constant holding the positive infinity of type double . |
static final int |
PRECISION |
The number of bits in the significand of a double value. |
static final int |
SIZE |
The number of bits used to represent a double value. |
static final Class |
TYPE |
The Class instance representing the primitive type double . |
Constructor | Description |
---|---|
Double |
Deprecated, for removal: This API element is subject to removal in a future version. It is rarely appropriate to use this constructor. |
Double |
Deprecated, for removal: This API element is subject to removal in a future version. It is rarely appropriate to use this constructor. |
Modifier and Type | Method | Description |
---|---|---|
byte |
byteValue() |
Returns the value of this Double as a byte after a narrowing primitive conversion. |
static int |
compare |
Compares the two specified double values. |
int |
compareTo |
Compares two Double objects numerically. |
Optional |
describeConstable() |
Returns an Optional containing the nominal descriptor for this instance, which is the instance itself. |
static long |
doubleToLongBits |
Returns a representation of the specified floating-point value according to the IEEE 754 floating-point "double format" bit layout. |
static long |
doubleToRawLongBits |
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 |
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 |
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 |
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 |
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 |
Returns true if the specified number is a Not-a-Number (NaN) value, false otherwise. |
static double |
longBitsToDouble |
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 |
Returns the greater of two double values as if by calling Math.max . |
static double |
min |
Returns the smaller of two double values as if by calling Math.min . |
static double |
parseDouble |
Returns a new double initialized to the value represented by the specified String , as performed by the valueOf method of class Double . |
Double |
resolveConstantDesc |
Resolves this instance as a ConstantDesc , the result of which is the instance itself. |
short |
shortValue() |
Returns the value of this Double as a short after a narrowing primitive conversion. |
static double |
sum |
Adds two double values together as per the + operator. |
static String |
toHexString |
Returns a hexadecimal string representation of the double argument. |
String |
toString() |
Returns a string representation of this Double object. |
static String |
toString |
Returns a string representation of the double argument. |
static Double |
valueOf |
Returns a Double instance representing the specified double value. |
static Double |
valueOf |
Returns a Double object holding the double value represented by the argument string s . |
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 SIZE
double
value.public static final int PRECISION
double
value. This is the parameter N in section 4.2.3 of The Java Language Specification.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 BYTES
double
value.public static final Class<Double> TYPE
Class
instance representing the primitive type double
.@Deprecated(since="9", forRemoval=true) public Double(double value)
valueOf(double)
is generally a better choice, as it is likely to yield significantly better space and time performance.Double
object that represents the primitive double
argument.value
- the value to be represented by the Double
.@Deprecated(since="9", forRemoval=true) public Double(String s) throws NumberFormatException
parseDouble(String)
to convert a string to a double
primitive, or use valueOf(String)
to convert a string to a Double
object.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.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"
. A decimal is a number of the form s×10i for some (unique) integers s > 0 and i such that s is not a multiple of 10. These integers are the significand and the exponent, respectively, of the decimal. The length of the decimal is the (unique) positive integer n meeting 10n-1 ≤ s < 10n.
The decimal dm for a finite positive m is defined as follows:
The (uniquely) selected decimal dm is then formatted. Let s, i and n be the significand, exponent and length of dm, respectively. Further, let e = n + i - 1 and let s1…sn be the usual decimal expansion of s. Note that s1 ≠ 0 and sn ≠ 0. Below, the decimal point '.'
is '\u002E'
and the exponent indicator 'E'
is '\u0045'
.
0.0
…0
s1…sn, where there are exactly -(n + i) zeroes between the decimal point and s1. For example, 123 × 10-4 is formatted as 0.0123
. 0
…0.0
, where there are exactly i zeroes between sn and the decimal point. For example, 123 × 102 is formatted as 12300.0
. .
sn+i+1…sn, where there are exactly -i digits to the right of the decimal point. For example, 123 × 10-1 is formatted as 12.3
. Integer.toString(int)
. .0E
e. For example, 1 × 1023 is formatted as 1.0E23
. .
s2…snE
e. For example, 123 × 10-21 is formatted as 1.23E-19
. 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 Java Language Specification, except that underscores are not accepted between digits. If
- FloatValue:
- Signopt
NaN
- Signopt
Infinity
- Signopt FloatingPointLiteral
- Signopt HexFloatingPointLiteral
- SignedInteger
- HexFloatingPointLiteral:
- HexSignificand BinaryExponent FloatTypeSuffixopt
- HexSignificand:
- HexNumeral
- HexNumeral
.
0x
HexDigitsopt.
HexDigits0X
HexDigitsopt.
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. 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
+ ulp(MAX_VALUE)
/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
}
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
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.d
- a double value.Double
instance representing d
.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.NullPointerException
- if the string is nullNumberFormatException
- if the string does not contain a parsable double
.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 static boolean isFinite(double d)
true
if the argument is a finite floating-point value; returns false
otherwise (for NaN and infinity arguments).d
- the double
value to be testedtrue
if the argument is a finite floating-point value, 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.public byte byteValue()
Double
as a byte
after a narrowing primitive conversion.byteValue
in class Number
double
value represented by this object converted to type byte
public short shortValue()
Double
as a short
after a narrowing primitive conversion.shortValue
in class Number
double
value represented by this object converted to type short
public int intValue()
Double
as an int
after a narrowing primitive conversion.intValue
in class Number
double
value represented by this object converted to type int
public long longValue()
Double
as a long
after a narrowing primitive conversion.longValue
in class Number
double
value represented by this object converted to type long
public float floatValue()
Double
as a float
after a narrowing primitive conversion.floatValue
in class Number
double
value represented by this object converted to type float
public double doubleValue()
double
value of this Double
object.doubleValue
in class Number
double
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: (int)(v^(v>>>32))
where v
is defined by: long v = Double.doubleToLongBits(this.doubleValue());
public static int hashCode(double value)
double
value; compatible with Double.hashCode()
.value
- the value to hashdouble
value.public 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.equals
in class Object
doubleToLongBits(double)
rather than the ==
operator on double
values since the ==
operator does not define an equivalence relation and to satisfy the equals contract an equivalence relation must be implemented; see this discussion for details of floating-point equality and equivalence.obj
- the reference object with which to compare.true
if this object is the same as the obj argument; false
otherwise.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. This method imposes a total order on Double
objects with two differences compared to the incomplete order defined by the Java language numerical comparison operators (<, <=,
==, >=, >
) on double
values.
Double.NaN
to be equal to itself and greater than all other double
values (including
Double.POSITIVE_INFINITY
). +0.0d
), to be greater than negative zero (-0.0d
). Double
objects imposed by this method is consistent with equals; see this discussion for details of floating-point comparison and ordering.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
.<
, <=
, >
, and >=
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: Double.valueOf(d1).compareTo(Double.valueOf(d2))
d1
- the first double
to compared2
- the second double
to compare0
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
.public static double sum(double a, double b)
double
values together as per the + operator.a
- the first operandb
- the second operanda
and b
public static double max(double a, double b)
double
values as if by calling Math.max
.a
- the first operandb
- the second operanda
and b
public static double min(double a, double b)
double
values as if by calling Math.min
.a
- the first operandb
- the second operanda
and b
.public Optional<Double> describeConstable()
Optional
containing the nominal descriptor for this instance, which is the instance itself.describeConstable
in interface Constable
Optional
describing the Double instancepublic Double resolveConstantDesc(MethodHandles.Lookup lookup)
ConstantDesc
, the result of which is the instance itself.resolveConstantDesc
in interface ConstantDesc
lookup
- ignored
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/Double.html