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package java.lang;
import java.lang.invoke.MethodHandles;
import java.lang.constant.Constable;
import java.lang.constant.ConstantDesc;
import java.util.Optional;
import jdk.internal.math.FloatingDecimal;
import jdk.internal.math.DoubleConsts;
import jdk.internal.vm.annotation.IntrinsicCandidate;
/**
* The {@code Double} class wraps a value of the primitive type
* {@code double} in an object. An object of type
* {@code Double} contains a single field whose type is
* {@code double}.
*
* In addition, this class provides several methods for converting a
* {@code double} to a {@code String} and a
* {@code String} to a {@code double}, as well as other
* constants and methods useful when dealing with a
* {@code double}.
*
*
This is a value-based
* class; programmers should treat instances that are
* {@linkplain #equals(Object) equal} as interchangeable and should not
* use instances for synchronization, or unpredictable behavior may
* occur. For example, in a future release, synchronization may fail.
*
*
Floating-point Equality, Equivalence,
* and Comparison
*
* IEEE 754 floating-point values include finite nonzero values,
* signed zeros ({@code +0.0} and {@code -0.0}), signed infinities
* {@linkplain Double#POSITIVE_INFINITY positive infinity} and
* {@linkplain Double#NEGATIVE_INFINITY negative infinity}), and
* {@linkplain Double#NaN 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 {@link Object#equals 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 {@code ==} operation on floating-point
* values is not an equivalence relation. Despite not
* defining an equivalence relation, the semantics of the IEEE 754
* {@code ==} 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 {@code
* ==} on floating-point values:
*
*
*
* - If {@code v1} and {@code v2} are both NaN, then {@code v1
* == v2} has the value {@code false}. Therefore, for two NaN
* arguments the reflexive property of an equivalence
* relation is not satisfied by the {@code ==} operator.
*
*
- If {@code v1} represents {@code +0.0} while {@code v2}
* represents {@code -0.0}, or vice versa, then {@code v1 == v2} has
* the value {@code true} even though {@code +0.0} and {@code -0.0}
* are distinguishable under various floating-point operations. For
* example, {@code 1.0/+0.0} evaluates to positive infinity while
* {@code 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, {@code +0.0} and {@code -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
* ({@code <}, {@code <=}, 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 {@code equals} and
* {@code compareTo} methods, those methods cannot simply be wrappers
* around {@code ==} or ordered comparison operations. Instead, {@link
* Double#equals equals} defines NaN arguments to be equal to each
* other and defines {@code +0.0} to not be equal to {@code
* -0.0}, restoring reflexivity. For comparisons, {@link
* Double#compareTo compareTo} defines a total order where {@code
* -0.0} is less than {@code +0.0} and where a NaN is equal to itself
* and considered greater than positive infinity.
*
*
The operational semantics of {@code equals} and {@code
* compareTo} are expressed in terms of {@linkplain #doubleToLongBits
* bit-wise converting} the floating-point values to integral values.
*
*
The natural ordering implemented by {@link #compareTo
* compareTo} is {@linkplain Comparable consistent with equals}. That
* is, two objects are reported as equal by {@code equals} if and only
* if {@code compareTo} on those objects returns zero.
*
*
The adjusted behaviors defined for {@code equals} and {@code
* compareTo} allow instances of wrapper classes to work properly with
* conventional data structures. For example, defining NaN
* values to be {@code equals} to one another allows NaN to be used as
* an element of a {@link java.util.HashSet HashSet} or as the key of
* a {@link java.util.HashMap HashMap}. Similarly, defining {@code
* compareTo} as a total ordering, including {@code +0.0}, {@code
* -0.0}, and NaN, allows instances of wrapper classes to be used as
* elements of a {@link java.util.SortedSet SortedSet} or as keys of a
* {@link java.util.SortedMap SortedMap}.
*
* @jls 4.2.3 Floating-Point Types, Formats, and Values
* @jls 4.2.4. Floating-Point Operations
* @jls 15.21.1 Numerical Equality Operators == and !=
* @jls 15.20.1 Numerical Comparison Operators {@code <}, {@code <=}, {@code >}, and {@code >=}
*
* @author Lee Boynton
* @author Arthur van Hoff
* @author Joseph D. Darcy
* @since 1.0
*/
@jdk.internal.ValueBased
public final class Double extends Number
implements Comparable, Constable, ConstantDesc {
/**
* A constant holding the positive infinity of type
* {@code double}. It is equal to the value returned by
* {@code Double.longBitsToDouble(0x7ff0000000000000L)}.
*/
public static final double POSITIVE_INFINITY = 1.0 / 0.0;
/**
* A constant holding the negative infinity of type
* {@code double}. It is equal to the value returned by
* {@code Double.longBitsToDouble(0xfff0000000000000L)}.
*/
public static final double NEGATIVE_INFINITY = -1.0 / 0.0;
/**
* A constant holding a Not-a-Number (NaN) value of type
* {@code double}. It is equivalent to the value returned by
* {@code Double.longBitsToDouble(0x7ff8000000000000L)}.
*/
public static final double NaN = 0.0d / 0.0;
/**
* A constant holding the largest positive finite value of type
* {@code double},
* (2-2-52)·21023. It is equal to
* the hexadecimal floating-point literal
* {@code 0x1.fffffffffffffP+1023} and also equal to
* {@code Double.longBitsToDouble(0x7fefffffffffffffL)}.
*/
public static final double MAX_VALUE = 0x1.fffffffffffffP+1023; // 1.7976931348623157e+308
/**
* A constant holding the smallest positive normal value of type
* {@code double}, 2-1022. It is equal to the
* hexadecimal floating-point literal {@code 0x1.0p-1022} and also
* equal to {@code Double.longBitsToDouble(0x0010000000000000L)}.
*
* @since 1.6
*/
public static final double MIN_NORMAL = 0x1.0p-1022; // 2.2250738585072014E-308
/**
* A constant holding the smallest positive nonzero value of type
* {@code double}, 2-1074. It is equal to the
* hexadecimal floating-point literal
* {@code 0x0.0000000000001P-1022} and also equal to
* {@code Double.longBitsToDouble(0x1L)}.
*/
public static final double MIN_VALUE = 0x0.0000000000001P-1022; // 4.9e-324
/**
* Maximum exponent a finite {@code double} variable may have.
* It is equal to the value returned by
* {@code Math.getExponent(Double.MAX_VALUE)}.
*
* @since 1.6
*/
public static final int MAX_EXPONENT = 1023;
/**
* Minimum exponent a normalized {@code double} variable may
* have. It is equal to the value returned by
* {@code Math.getExponent(Double.MIN_NORMAL)}.
*
* @since 1.6
*/
public static final int MIN_EXPONENT = -1022;
/**
* The number of bits used to represent a {@code double} value.
*
* @since 1.5
*/
public static final int SIZE = 64;
/**
* The number of bytes used to represent a {@code double} value.
*
* @since 1.8
*/
public static final int BYTES = SIZE / Byte.SIZE;
/**
* The {@code Class} instance representing the primitive type
* {@code double}.
*
* @since 1.1
*/
@SuppressWarnings("unchecked")
public static final Class TYPE = (Class) Class.getPrimitiveClass("double");
/**
* Returns a string representation of the {@code double}
* argument. All characters mentioned below are ASCII characters.
*
* - If the argument is NaN, the result is the string
* "{@code 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 '{@code -}'
* ({@code '\u005Cu002D'}); 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
* {@code "Infinity"}; thus, positive infinity produces the result
* {@code "Infinity"} and negative infinity produces the result
* {@code "-Infinity"}.
*
*
- If m is zero, it is represented by the characters
* {@code "0.0"}; thus, negative zero produces the result
* {@code "-0.0"} and positive zero produces the result
* {@code "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
* '{@code .}' ({@code '\u005Cu002E'}), 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 {@literal <}
* 10n+1; then let a be the
* mathematically exact quotient of m and
* 10n so that 1 ≤ a {@literal <} 10. The
* magnitude is then represented as the integer part of a,
* as a single decimal digit, followed by '{@code .}'
* ({@code '\u005Cu002E'}), followed by decimal digits
* representing the fractional part of a, followed by the
* letter '{@code E}' ({@code '\u005Cu0045'}), followed
* by a representation of n as a decimal integer, as
* produced by the method {@link 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 {@code 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 {@code double} value nearest
* to x; or if two {@code 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 {@code 0}.
*
* To create localized string representations of a floating-point
* value, use subclasses of {@link java.text.NumberFormat}.
*
* @param d the {@code double} to be converted.
* @return a string representation of the argument.
*/
public static String toString(double d) {
return FloatingDecimal.toJavaFormatString(d);
}
/**
* Returns a hexadecimal string representation of the
* {@code double} argument. All characters mentioned below
* are ASCII characters.
*
*
* - If the argument is NaN, the result is the string
* "{@code 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 '{@code -}'
* ({@code '\u005Cu002D'}); 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
* {@code "Infinity"}; thus, positive infinity produces the
* result {@code "Infinity"} and negative infinity produces
* the result {@code "-Infinity"}.
*
*
- If m is zero, it is represented by the string
* {@code "0x0.0p0"}; thus, negative zero produces the result
* {@code "-0x0.0p0"} and positive zero produces the result
* {@code "0x0.0p0"}.
*
*
- If m is a {@code double} value with a
* normalized representation, substrings are used to represent the
* significand and exponent fields. The significand is
* represented by the characters {@code "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 {@code "p"} followed
* by a decimal string of the unbiased exponent as if produced by
* a call to {@link Integer#toString(int) Integer.toString} on the
* exponent value.
*
*
- If m is a {@code double} value with a subnormal
* representation, the significand is represented by the
* characters {@code "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
* {@code "p-1022"}. Note that there must be at
* least one nonzero digit in a subnormal significand.
*
*
*
*
*
*
* Examples
*
* Floating-point Value Hexadecimal String
* {@code 1.0} {@code 0x1.0p0}
* {@code -1.0} {@code -0x1.0p0}
* {@code 2.0} {@code 0x1.0p1}
* {@code 3.0} {@code 0x1.8p1}
* {@code 0.5} {@code 0x1.0p-1}
* {@code 0.25} {@code 0x1.0p-2}
* {@code Double.MAX_VALUE}
* {@code 0x1.fffffffffffffp1023}
* {@code Minimum Normal Value}
* {@code 0x1.0p-1022}
* {@code Maximum Subnormal Value}
* {@code 0x0.fffffffffffffp-1022}
* {@code Double.MIN_VALUE}
* {@code 0x0.0000000000001p-1022}
*
* @param d the {@code double} to be converted.
* @return a hex string representation of the argument.
* @since 1.5
* @author Joseph D. Darcy
*/
public static String toHexString(double d) {
/*
* Modeled after the "a" conversion specifier in C99, section
* 7.19.6.1; however, the output of this method is more
* tightly specified.
*/
if (!isFinite(d) )
// For infinity and NaN, use the decimal output.
return Double.toString(d);
else {
// Initialized to maximum size of output.
StringBuilder answer = new StringBuilder(24);
if (Math.copySign(1.0, d) == -1.0) // value is negative,
answer.append("-"); // so append sign info
answer.append("0x");
d = Math.abs(d);
if(d == 0.0) {
answer.append("0.0p0");
} else {
boolean subnormal = (d < Double.MIN_NORMAL);
// Isolate significand bits and OR in a high-order bit
// so that the string representation has a known
// length.
long signifBits = (Double.doubleToLongBits(d)
& DoubleConsts.SIGNIF_BIT_MASK) |
0x1000000000000000L;
// Subnormal values have a 0 implicit bit; normal
// values have a 1 implicit bit.
answer.append(subnormal ? "0." : "1.");
// Isolate the low-order 13 digits of the hex
// representation. If all the digits are zero,
// replace with a single 0; otherwise, remove all
// trailing zeros.
String signif = Long.toHexString(signifBits).substring(3,16);
answer.append(signif.equals("0000000000000") ? // 13 zeros
"0":
signif.replaceFirst("0{1,12}$", ""));
answer.append('p');
// If the value is subnormal, use the E_min exponent
// value for double; otherwise, extract and report d's
// exponent (the representation of a subnormal uses
// E_min -1).
answer.append(subnormal ?
Double.MIN_EXPONENT:
Math.getExponent(d));
}
return answer.toString();
}
}
/**
* Returns a {@code Double} object holding the
* {@code double} value represented by the argument string
* {@code s}.
*
* If {@code s} is {@code null}, then a
* {@code NullPointerException} is thrown.
*
*
Leading and trailing whitespace characters in {@code s}
* are ignored. Whitespace is removed as if by the {@link
* String#trim} method; that is, both ASCII space and control
* characters are removed. The rest of {@code s} should
* constitute a FloatValue as described by the lexical
* syntax rules:
*
*
*
* - FloatValue:
*
- Signopt {@code NaN}
*
- Signopt {@code Infinity}
*
- Signopt FloatingPointLiteral
*
- Signopt HexFloatingPointLiteral
*
- SignedInteger
*
*
*
* - HexFloatingPointLiteral:
*
- HexSignificand BinaryExponent FloatTypeSuffixopt
*
*
*
* - HexSignificand:
*
- HexNumeral
*
- HexNumeral {@code .}
*
- {@code 0x} HexDigitsopt
* {@code .} HexDigits
*
- {@code 0X} HexDigitsopt
* {@code .} HexDigits
*
*
*
* - BinaryExponent:
*
- BinaryExponentIndicator SignedInteger
*
*
*
* - BinaryExponentIndicator:
*
- {@code p}
*
- {@code 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 {@code s} does not have the form of
* a FloatValue, then a {@code NumberFormatException}
* is thrown. Otherwise, {@code 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 {@code 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 {@code s} is large
* enough in magnitude (greater than or equal to ({@link
* #MAX_VALUE} + {@link Math#ulp(double) ulp(MAX_VALUE)}/2),
* rounding to {@code double} will result in an infinity and if the
* exact value of {@code s} is small enough in magnitude (less
* than or equal to {@link #MIN_VALUE}/2), rounding to float will
* result in a zero.
*
* Finally, after rounding a {@code Double} object representing
* this {@code double} value is returned.
*
* To interpret localized string representations of a
* floating-point value, use subclasses of {@link
* java.text.NumberFormat}.
*
*
Note that trailing format specifiers, specifiers that
* determine the type of a floating-point literal
* ({@code 1.0f} is a {@code float} value;
* {@code 1.0d} is a {@code 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 {@code float} followed
* by {@code float} to {@code double}, is not
* equivalent to converting a string directly to
* {@code double}. For example, the {@code float}
* literal {@code 0.1f} is equal to the {@code double}
* value {@code 0.10000000149011612}; the {@code float}
* literal {@code 0.1f} represents a different numerical
* value than the {@code double} literal
* {@code 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 {@code NumberFormatException} be thrown, the regular
* expression below can be used to screen the input string:
*
*
{@code
* 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
* }
* }
*
* @param s the string to be parsed.
* @return a {@code Double} object holding the value
* represented by the {@code String} argument.
* @throws NumberFormatException if the string does not contain a
* parsable number.
*/
public static Double valueOf(String s) throws NumberFormatException {
return new Double(parseDouble(s));
}
/**
* Returns a {@code Double} instance representing the specified
* {@code double} value.
* If a new {@code Double} instance is not required, this method
* should generally be used in preference to the constructor
* {@link #Double(double)}, as this method is likely to yield
* significantly better space and time performance by caching
* frequently requested values.
*
* @param d a double value.
* @return a {@code Double} instance representing {@code d}.
* @since 1.5
*/
@IntrinsicCandidate
public static Double valueOf(double d) {
return new Double(d);
}
/**
* Returns a new {@code double} initialized to the value
* represented by the specified {@code String}, as performed
* by the {@code valueOf} method of class
* {@code Double}.
*
* @param s the string to be parsed.
* @return the {@code double} value represented by the string
* argument.
* @throws NullPointerException if the string is null
* @throws NumberFormatException if the string does not contain
* a parsable {@code double}.
* @see java.lang.Double#valueOf(String)
* @since 1.2
*/
public static double parseDouble(String s) throws NumberFormatException {
return FloatingDecimal.parseDouble(s);
}
/**
* Returns {@code true} if the specified number is a
* Not-a-Number (NaN) value, {@code false} otherwise.
*
* @param v the value to be tested.
* @return {@code true} if the value of the argument is NaN;
* {@code false} otherwise.
*/
public static boolean isNaN(double v) {
return (v != v);
}
/**
* Returns {@code true} if the specified number is infinitely
* large in magnitude, {@code false} otherwise.
*
* @param v the value to be tested.
* @return {@code true} if the value of the argument is positive
* infinity or negative infinity; {@code false} otherwise.
*/
public static boolean isInfinite(double v) {
return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
}
/**
* Returns {@code true} if the argument is a finite floating-point
* value; returns {@code false} otherwise (for NaN and infinity
* arguments).
*
* @param d the {@code double} value to be tested
* @return {@code true} if the argument is a finite
* floating-point value, {@code false} otherwise.
* @since 1.8
*/
public static boolean isFinite(double d) {
return Math.abs(d) <= Double.MAX_VALUE;
}
/**
* The value of the Double.
*
* @serial
*/
private final double value;
/**
* Constructs a newly allocated {@code Double} object that
* represents the primitive {@code double} argument.
*
* @param value the value to be represented by the {@code Double}.
*
* @deprecated
* It is rarely appropriate to use this constructor. The static factory
* {@link #valueOf(double)} is generally a better choice, as it is
* likely to yield significantly better space and time performance.
*/
@Deprecated(since="9", forRemoval = true)
public Double(double value) {
this.value = value;
}
/**
* Constructs a newly allocated {@code Double} object that
* represents the floating-point value of type {@code double}
* represented by the string. The string is converted to a
* {@code double} value as if by the {@code valueOf} method.
*
* @param s a string to be converted to a {@code Double}.
* @throws NumberFormatException if the string does not contain a
* parsable number.
*
* @deprecated
* It is rarely appropriate to use this constructor.
* Use {@link #parseDouble(String)} to convert a string to a
* {@code double} primitive, or use {@link #valueOf(String)}
* to convert a string to a {@code Double} object.
*/
@Deprecated(since="9", forRemoval = true)
public Double(String s) throws NumberFormatException {
value = parseDouble(s);
}
/**
* Returns {@code true} if this {@code Double} value is
* a Not-a-Number (NaN), {@code false} otherwise.
*
* @return {@code true} if the value represented by this object is
* NaN; {@code false} otherwise.
*/
public boolean isNaN() {
return isNaN(value);
}
/**
* Returns {@code true} if this {@code Double} value is
* infinitely large in magnitude, {@code false} otherwise.
*
* @return {@code true} if the value represented by this object is
* positive infinity or negative infinity;
* {@code false} otherwise.
*/
public boolean isInfinite() {
return isInfinite(value);
}
/**
* Returns a string representation of this {@code Double} object.
* The primitive {@code double} value represented by this
* object is converted to a string exactly as if by the method
* {@code toString} of one argument.
*
* @return a {@code String} representation of this object.
* @see java.lang.Double#toString(double)
*/
public String toString() {
return toString(value);
}
/**
* Returns the value of this {@code Double} as a {@code byte}
* after a narrowing primitive conversion.
*
* @return the {@code double} value represented by this object
* converted to type {@code byte}
* @jls 5.1.3 Narrowing Primitive Conversion
* @since 1.1
*/
public byte byteValue() {
return (byte)value;
}
/**
* Returns the value of this {@code Double} as a {@code short}
* after a narrowing primitive conversion.
*
* @return the {@code double} value represented by this object
* converted to type {@code short}
* @jls 5.1.3 Narrowing Primitive Conversion
* @since 1.1
*/
public short shortValue() {
return (short)value;
}
/**
* Returns the value of this {@code Double} as an {@code int}
* after a narrowing primitive conversion.
* @jls 5.1.3 Narrowing Primitive Conversion
*
* @return the {@code double} value represented by this object
* converted to type {@code int}
*/
public int intValue() {
return (int)value;
}
/**
* Returns the value of this {@code Double} as a {@code long}
* after a narrowing primitive conversion.
*
* @return the {@code double} value represented by this object
* converted to type {@code long}
* @jls 5.1.3 Narrowing Primitive Conversion
*/
public long longValue() {
return (long)value;
}
/**
* Returns the value of this {@code Double} as a {@code float}
* after a narrowing primitive conversion.
*
* @return the {@code double} value represented by this object
* converted to type {@code float}
* @jls 5.1.3 Narrowing Primitive Conversion
* @since 1.0
*/
public float floatValue() {
return (float)value;
}
/**
* Returns the {@code double} value of this {@code Double} object.
*
* @return the {@code double} value represented by this object
*/
@IntrinsicCandidate
public double doubleValue() {
return value;
}
/**
* Returns a hash code for this {@code Double} object. The
* result is the exclusive OR of the two halves of the
* {@code long} integer bit representation, exactly as
* produced by the method {@link #doubleToLongBits(double)}, of
* the primitive {@code double} value represented by this
* {@code Double} object. That is, the hash code is the value
* of the expression:
*
*
* {@code (int)(v^(v>>>32))}
*
*
* where {@code v} is defined by:
*
*
* {@code long v = Double.doubleToLongBits(this.doubleValue());}
*
*
* @return a {@code hash code} value for this object.
*/
@Override
public int hashCode() {
return Double.hashCode(value);
}
/**
* Returns a hash code for a {@code double} value; compatible with
* {@code Double.hashCode()}.
*
* @param value the value to hash
* @return a hash code value for a {@code double} value.
* @since 1.8
*/
public static int hashCode(double value) {
long bits = doubleToLongBits(value);
return (int)(bits ^ (bits >>> 32));
}
/**
* Compares this object against the specified object. The result
* is {@code true} if and only if the argument is not
* {@code null} and is a {@code Double} object that
* represents a {@code double} that has the same value as the
* {@code double} represented by this object. For this
* purpose, two {@code double} values are considered to be
* the same if and only if the method {@link
* #doubleToLongBits(double)} returns the identical
* {@code long} value when applied to each.
*
* @apiNote
* This method is defined in terms of {@link
* #doubleToLongBits(double)} rather than the {@code ==} operator
* on {@code double} values since the {@code ==} operator does
* not define an equivalence relation and to satisfy the
* {@linkplain Object#equals equals contract} an equivalence
* relation must be implemented; see this discussion for details of
* floating-point equality and equivalence.
*
* @see java.lang.Double#doubleToLongBits(double)
* @jls 15.21.1 Numerical Equality Operators == and !=
*/
public boolean equals(Object obj) {
return (obj instanceof Double)
&& (doubleToLongBits(((Double)obj).value) ==
doubleToLongBits(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
* {@code 0x8000000000000000L}) represents the sign of the
* floating-point number. Bits
* 62-52 (the bits that are selected by the mask
* {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0
* (the bits that are selected by the mask
* {@code 0x000fffffffffffffL}) represent the significand
* (sometimes called the mantissa) of the floating-point number.
*
*
If the argument is positive infinity, the result is
* {@code 0x7ff0000000000000L}.
*
*
If the argument is negative infinity, the result is
* {@code 0xfff0000000000000L}.
*
*
If the argument is NaN, the result is
* {@code 0x7ff8000000000000L}.
*
*
In all cases, the result is a {@code long} integer that, when
* given to the {@link #longBitsToDouble(long)} method, will produce a
* floating-point value the same as the argument to
* {@code doubleToLongBits} (except all NaN values are
* collapsed to a single "canonical" NaN value).
*
* @param value a {@code double} precision floating-point number.
* @return the bits that represent the floating-point number.
*/
@IntrinsicCandidate
public static long doubleToLongBits(double value) {
if (!isNaN(value)) {
return doubleToRawLongBits(value);
}
return 0x7ff8000000000000L;
}
/**
* 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
* {@code 0x8000000000000000L}) represents the sign of the
* floating-point number. Bits
* 62-52 (the bits that are selected by the mask
* {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0
* (the bits that are selected by the mask
* {@code 0x000fffffffffffffL}) represent the significand
* (sometimes called the mantissa) of the floating-point number.
*
*
If the argument is positive infinity, the result is
* {@code 0x7ff0000000000000L}.
*
*
If the argument is negative infinity, the result is
* {@code 0xfff0000000000000L}.
*
*
If the argument is NaN, the result is the {@code long}
* integer representing the actual NaN value. Unlike the
* {@code doubleToLongBits} method,
* {@code doubleToRawLongBits} does not collapse all the bit
* patterns encoding a NaN to a single "canonical" NaN
* value.
*
*
In all cases, the result is a {@code long} integer that,
* when given to the {@link #longBitsToDouble(long)} method, will
* produce a floating-point value the same as the argument to
* {@code doubleToRawLongBits}.
*
* @param value a {@code double} precision floating-point number.
* @return the bits that represent the floating-point number.
* @since 1.3
*/
@IntrinsicCandidate
public static native long doubleToRawLongBits(double value);
/**
* Returns the {@code 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 {@code 0x7ff0000000000000L}, the result
* is positive infinity.
*
*
If the argument is {@code 0xfff0000000000000L}, the result
* is negative infinity.
*
*
If the argument is any value in the range
* {@code 0x7ff0000000000001L} through
* {@code 0x7fffffffffffffffL} or in the range
* {@code 0xfff0000000000001L} through
* {@code 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 {@code Double.doubleToRawLongBits} method.
*
*
In all other cases, let s, e, and m be three
* values that can be computed from the argument:
*
*
{@code
* 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.
*
* Note that this method may not be able to return a
* {@code double} NaN with exactly same bit pattern as the
* {@code 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 {@code longBitsToDouble}
* may not be able to return a {@code double} with a
* signaling NaN bit pattern. Consequently, for some
* {@code long} values,
* {@code doubleToRawLongBits(longBitsToDouble(start))} may
* not equal {@code 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.
*
* @param bits any {@code long} integer.
* @return the {@code double} floating-point value with the same
* bit pattern.
*/
@IntrinsicCandidate
public static native double longBitsToDouble(long bits);
/**
* Compares two {@code Double} objects numerically.
*
* This method imposes a total order on {@code Double} objects
* with two differences compared to the incomplete order defined by
* the Java language numerical comparison operators ({@code <, <=,
* ==, >=, >}) on {@code double} values.
*
*
- A NaN is unordered with respect to other
* values and unequal to itself under the comparison
* operators. This method chooses to define {@code
* Double.NaN} to be equal to itself and greater than all
* other {@code double} values (including {@code
* Double.POSITIVE_INFINITY}).
*
*
- Positive zero and negative zero compare equal
* numerically, but are distinct and distinguishable values.
* This method chooses to define positive zero ({@code +0.0d}),
* to be greater than negative zero ({@code -0.0d}).
*
* This ensures that the natural ordering of {@code Double}
* objects imposed by this method is consistent with
* equals; see this
* discussion for details of floating-point comparison and
* ordering.
*
* @param anotherDouble the {@code Double} to be compared.
* @return the value {@code 0} if {@code anotherDouble} is
* numerically equal to this {@code Double}; a value
* less than {@code 0} if this {@code Double}
* is numerically less than {@code anotherDouble};
* and a value greater than {@code 0} if this
* {@code Double} is numerically greater than
* {@code anotherDouble}.
*
* @jls 15.20.1 Numerical Comparison Operators {@code <}, {@code <=}, {@code >}, and {@code >=}
* @since 1.2
*/
public int compareTo(Double anotherDouble) {
return Double.compare(value, anotherDouble.value);
}
/**
* Compares the two specified {@code 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))
*
*
* @param d1 the first {@code double} to compare
* @param d2 the second {@code double} to compare
* @return the value {@code 0} if {@code d1} is
* numerically equal to {@code d2}; a value less than
* {@code 0} if {@code d1} is numerically less than
* {@code d2}; and a value greater than {@code 0}
* if {@code d1} is numerically greater than
* {@code d2}.
* @since 1.4
*/
public static int compare(double d1, double d2) {
if (d1 < d2)
return -1; // Neither val is NaN, thisVal is smaller
if (d1 > d2)
return 1; // Neither val is NaN, thisVal is larger
// Cannot use doubleToRawLongBits because of possibility of NaNs.
long thisBits = Double.doubleToLongBits(d1);
long anotherBits = Double.doubleToLongBits(d2);
return (thisBits == anotherBits ? 0 : // Values are equal
(thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
1)); // (0.0, -0.0) or (NaN, !NaN)
}
/**
* Adds two {@code double} values together as per the + operator.
*
* @param a the first operand
* @param b the second operand
* @return the sum of {@code a} and {@code b}
* @jls 4.2.4 Floating-Point Operations
* @see java.util.function.BinaryOperator
* @since 1.8
*/
public static double sum(double a, double b) {
return a + b;
}
/**
* Returns the greater of two {@code double} values
* as if by calling {@link Math#max(double, double) Math.max}.
*
* @param a the first operand
* @param b the second operand
* @return the greater of {@code a} and {@code b}
* @see java.util.function.BinaryOperator
* @since 1.8
*/
public static double max(double a, double b) {
return Math.max(a, b);
}
/**
* Returns the smaller of two {@code double} values
* as if by calling {@link Math#min(double, double) Math.min}.
*
* @param a the first operand
* @param b the second operand
* @return the smaller of {@code a} and {@code b}.
* @see java.util.function.BinaryOperator
* @since 1.8
*/
public static double min(double a, double b) {
return Math.min(a, b);
}
/**
* Returns an {@link Optional} containing the nominal descriptor for this
* instance, which is the instance itself.
*
* @return an {@link Optional} describing the {@linkplain Double} instance
* @since 12
*/
@Override
public Optional describeConstable() {
return Optional.of(this);
}
/**
* Resolves this instance as a {@link ConstantDesc}, the result of which is
* the instance itself.
*
* @param lookup ignored
* @return the {@linkplain Double} instance
* @since 12
*/
@Override
public Double resolveConstantDesc(MethodHandles.Lookup lookup) {
return this;
}
/** use serialVersionUID from JDK 1.0.2 for interoperability */
@java.io.Serial
private static final long serialVersionUID = -9172774392245257468L;
}