Fields Summary |
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public static final double | POSITIVE_INFINITYThe positive infinity of type double .
It is equal to the value returned by
Double.longBitsToDouble(0x7ff0000000000000L) . |
public static final double | NEGATIVE_INFINITYThe negative infinity of type double .
It is equal to the value returned by
Double.longBitsToDouble(0xfff0000000000000L) . |
public static final double | NaNA Not-a-Number (NaN) value of type double .
It is equal to the value returned by
Double.longBitsToDouble(0x7ff8000000000000L) . |
public static final double | MAX_VALUEThe largest positive finite value of type double .
It is equal to the value returned by
Double.longBitsToDouble(0x7fefffffffffffffL)
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public static final double | MIN_VALUEThe smallest positive value of type double .
It is equal to the value returned by
Double.longBitsToDouble(0x1L) . |
private double | valueThe value of the Double. |
Methods Summary |
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public byte | byteValue()Returns the value of this Double as a byte (by casting to a byte).
return (byte)value;
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public static native 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 {@link #longBitsToDouble(long)} method, will produce a
floating-point value equal to the argument to
doubleToLongBits .
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public double | doubleValue()Returns the double value of this Double.
return (double)value;
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public boolean | equals(java.lang.Object obj)Compares this object against the specified object.
The result is true if and only if the argument is
not null and is a Double object that
represents a double that has the identical bit pattern to the bit
pattern of the double represented by this object. For this purpose,
two double values are considered to be the same if and
only if the method {@link #doubleToLongBits(double)} returns the same
long value when applied to each.
Note that in most cases, for two instances of class
Double , d1 and d2 , the
value of d1.equals(d2) is true if and
only if
d1.doubleValue() == d2.doubleValue()
also has the value true . However, there are two
exceptions:
- If
d1 and d2 both represent
Double.NaN , then the equals method
returns true , even though
Double.NaN==Double.NaN has the value
false .
- If
d1 represents +0.0 while
d2 represents -0.0 , or vice versa,
the equals test has the value false ,
even though +0.0==-0.0 has the value true .
This allows hashtables to operate properly.
return (obj instanceof Double)
&& (doubleToLongBits(((Double)obj).value) ==
doubleToLongBits(value));
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public float | floatValue()Returns the float value of this Double.
return (float)value;
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public int | hashCode()Returns a hashcode for this Double object. The result
is the exclusive OR of the two halves of the long integer bit
representation, exactly as produced by the method
{@link #doubleToLongBits(double)}, of the primitive
double value represented by this Double
object. That is, the hashcode is the value of the expression:
(int)(v^(v>>>32))
where v is defined by:
long v = Double.doubleToLongBits(this.doubleValue());
long bits = doubleToLongBits(value);
return (int)(bits ^ (bits >>> 32));
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public int | intValue()Returns the integer value of this Double (by casting to an int).
return (int)value;
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public static boolean | isInfinite(double v)Returns true if the specified number is infinitely large in magnitude.
return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
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public boolean | isInfinite()Returns true if this Double value is infinitely large in magnitude.
return isInfinite(value);
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public static boolean | isNaN(double v)Returns true if the specified number is the special Not-a-Number (NaN)
value.
return (v != v);
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public boolean | isNaN()Returns true if this Double value is the special Not-a-Number (NaN)
value.
return isNaN(value);
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public static native double | longBitsToDouble(long bits)Returns the double-float corresponding to a given bit representation.
The argument is considered to be a representation of a
floating-point value according to the IEEE 754 floating-point
"double precision" bit layout. That floating-point
value is returned as the result.
If the argument is 0x7ff0000000000000L , the result
is positive infinity.
If the argument is 0xfff0000000000000L , the result
is negative infinity.
If the argument is any value in the range
0x7ff0000000000001L through
0x7fffffffffffffffL or in the range
0xfff0000000000001L through
0xffffffffffffffffL , the result is NaN. All IEEE 754
NaN values of type double are, in effect, lumped together
by the Java programming language into a single value called NaN.
In all other cases, let s, e, and m be three
values that can be computed from the argument:
int s = ((bits >> 63) == 0) ? 1 : -1;
int e = (int)((bits >> 52) & 0x7ffL);
long m = (e == 0) ?
(bits & 0xfffffffffffffL) << 1 :
(bits & 0xfffffffffffffL) | 0x10000000000000L;
Then the floating-point result equals the value of the mathematical
expression s·m·2e-1075.
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public long | longValue()Returns the long value of this Double (by casting to a long).
return (long)value;
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public static double | parseDouble(java.lang.String s)Returns a new double initialized to the value represented by the
specified String , as performed by the valueOf
method of class Double .
return FloatingDecimal.readJavaFormatString(s).doubleValue();
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public short | shortValue()Returns the value of this Double as a short (by casting to a short).
return (short)value;
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public static java.lang.String | toString(double d)Creates a string representation of the double
argument. All characters mentioned below are ASCII characters.
- If the argument is NaN, the result is the string "NaN".
- Otherwise, the result is a string that represents the sign and
magnitude (absolute value) of the argument. If the sign is negative,
the first character of the result is '
- '
('\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 not less than
107, then it is represented in so-called "computerized
scientific notation." Let n be the unique integer such that
10n<=m<10n+1; then let a be
the mathematically exact quotient of m and 10n so
that 1<=a<10. The magnitude is then represented as the
integer part of a, as a single decimal digit, followed
by
'.' (\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
{@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 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 .
return new FloatingDecimal(d).toJavaFormatString();
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public java.lang.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.
return String.valueOf(value);
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public static java.lang.Double | valueOf(java.lang.String s)Returns a new Double object initialized to the value
represented by the specified string. The string s is
interpreted as the representation of a floating-point value and a
Double object representing that value is created and
returned.
If s is null , then a
NullPointerException is thrown.
Leading and trailing whitespace characters in s are ignored. The rest
of s should constitute a FloatValue as described
by the lexical rule:
FloatValue:
Signopt FloatingPointLiteral
where Sign and FloatingPointLiteral are as defined in
Section 3.10.2 of the Java
Language Specification. If it does not have the form of a
FloatValue, then a NumberFormatException is
thrown. Otherwise, it is regarded as representing an exact decimal
value in the usual "computerized scientific notation"; this exact
decimal value is then conceptually converted to an "infinitely
precise" binary value that is then rounded to type double
by the usual round-to-nearest rule of IEEE 754 floating-point
arithmetic. Finally, a new object of class Double is
created to represent the double value.
return new Double(FloatingDecimal.readJavaFormatString(s).doubleValue());
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