Immutable, arbitrary-precision signed decimal numbers. A
BigDecimal consists of an arbitrary precision integer
unscaled value and a 32-bit integer
scale. If zero
or positive, the scale is the number of digits to the right of the
decimal point. If negative, the unscaled value of the number is
multiplied by ten to the power of the negation of the scale. The
value of the number represented by the
BigDecimal is
therefore
(unscaledValue × 10-scale).
The BigDecimal class provides operations for
arithmetic, scale manipulation, rounding, comparison, hashing, and
format conversion. The #toString
method provides a
canonical representation of a BigDecimal.
The BigDecimal class gives its user complete control
over rounding behavior. If no rounding mode is specified and the
exact result cannot be represented, an exception is thrown;
otherwise, calculations can be carried out to a chosen precision
and rounding mode by supplying an appropriate MathContext
object to the operation. In either case, eight rounding
modes are provided for the control of rounding. Using the
integer fields in this class (such as #ROUND_HALF_UP
) to
represent rounding mode is largely obsolete; the enumeration values
of the RoundingMode enum, (such as RoundingMode#HALF_UP
) should be used instead.
When a MathContext object is supplied with a precision
setting of 0 (for example, MathContext#UNLIMITED
),
arithmetic operations are exact, as are the arithmetic methods
which take no MathContext object. (This is the only
behavior that was supported in releases prior to 5.) As a
corollary of computing the exact result, the rounding mode setting
of a MathContext object with a precision setting of 0 is
not used and thus irrelevant. In the case of divide, the exact
quotient could have an infinitely long decimal expansion; for
example, 1 divided by 3. If the quotient has a nonterminating
decimal expansion and the operation is specified to return an exact
result, an ArithmeticException is thrown. Otherwise, the
exact result of the division is returned, as done for other
operations.
When the precision setting is not 0, the rules of
BigDecimal arithmetic are broadly compatible with selected
modes of operation of the arithmetic defined in ANSI X3.274-1996
and ANSI X3.274-1996/AM 1-2000 (section 7.4). Unlike those
standards, BigDecimal includes many rounding modes, which
were mandatory for division in BigDecimal releases prior
to 5. Any conflicts between these ANSI standards and the
BigDecimal specification are resolved in favor of
BigDecimal.
Since the same numerical value can have different
representations (with different scales), the rules of arithmetic
and rounding must specify both the numerical result and the scale
used in the result's representation.
In general the rounding modes and precision setting determine
how operations return results with a limited number of digits when
the exact result has more digits (perhaps infinitely many in the
case of division) than the number of digits returned.
First, the
total number of digits to return is specified by the
MathContext's precision setting; this determines
the result's precision. The digit count starts from the
leftmost nonzero digit of the exact result. The rounding mode
determines how any discarded trailing digits affect the returned
result.
For all arithmetic operators , the operation is carried out as
though an exact intermediate result were first calculated and then
rounded to the number of digits specified by the precision setting
(if necessary), using the selected rounding mode. If the exact
result is not returned, some digit positions of the exact result
are discarded. When rounding increases the magnitude of the
returned result, it is possible for a new digit position to be
created by a carry propagating to a leading "9" digit.
For example, rounding the value 999.9 to three digits rounding up
would be numerically equal to one thousand, represented as
100×101. In such cases, the new "1" is
the leading digit position of the returned result.
Besides a logical exact result, each arithmetic operation has a
preferred scale for representing a result. The preferred
scale for each operation is listed in the table below.
Preferred Scales for Results of Arithmetic Operations
| Operation | Preferred Scale of Result |
|---|
| Add | max(addend.scale(), augend.scale()) |
| Subtract | max(minuend.scale(), subtrahend.scale()) |
| Multiply | multiplier.scale() + multiplicand.scale() |
| Divide | dividend.scale() - divisor.scale() |
These scales are the ones used by the methods which return exact
arithmetic results; except that an exact divide may have to use a
larger scale since the exact result may have more digits. For
example,
1/32 is
0.03125.
Before rounding, the scale of the logical exact intermediate
result is the preferred scale for that operation. If the exact
numerical result cannot be represented in precision
digits, rounding selects the set of digits to return and the scale
of the result is reduced from the scale of the intermediate result
to the least scale which can represent the precision
digits actually returned. If the exact result can be represented
with at most precision digits, the representation
of the result with the scale closest to the preferred scale is
returned. In particular, an exactly representable quotient may be
represented in fewer than precision digits by removing
trailing zeros and decreasing the scale. For example, rounding to
three digits using the
rounding mode,
19/100 = 0.19 // integer=19, scale=2
but
21/110 = 0.190 // integer=190, scale=3
Note that for add, subtract, and multiply, the reduction in
scale will equal the number of digit positions of the exact result
which are discarded. If the rounding causes a carry propagation to
create a new high-order digit position, an additional digit of the
result is discarded than when no new digit position is created.
Other methods may have slightly different rounding semantics.
For example, the result of the pow method using the
can
occasionally differ from the rounded mathematical result by more
than one unit in the last place, one .
Two types of operations are provided for manipulating the scale
of a BigDecimal: scaling/rounding operations and decimal
point motion operations. Scaling/rounding operations (setScale
and round
) return a
BigDecimal whose value is approximately (or exactly) equal
to that of the operand, but whose scale or precision is the
specified value; that is, they increase or decrease the precision
of the stored number with minimal effect on its value. Decimal
point motion operations (movePointLeft
and
movePointRight
) return a
BigDecimal created from the operand by moving the decimal
point a specified distance in the specified direction.
For the sake of brevity and clarity, pseudo-code is used
throughout the descriptions of BigDecimal methods. The
pseudo-code expression (i + j) is shorthand for "a
BigDecimal whose value is that of the BigDecimal
i added to that of the BigDecimal
j." The pseudo-code expression (i == j) is
shorthand for "true if and only if the
BigDecimal i represents the same value as the
BigDecimal j." Other pseudo-code expressions
are interpreted similarly. Square brackets are used to represent
the particular BigInteger and scale pair defining a
BigDecimal value; for example [19, 2] is the
BigDecimal numerically equal to 0.19 having a scale of 2.
Note: care should be exercised if BigDecimal objects
are used as keys in a SortedMap
or
elements in a SortedSet
since
BigDecimal's natural ordering is inconsistent
with equals. See Comparable
, java.util.SortedMap
or java.util.SortedSet
for more
information.
All methods and constructors for this class throw
NullPointerException when passed a null object
reference for any input parameter.
Translates a character array representation of a
BigDecimal into a
BigDecimal, accepting the
same sequence of characters as the
constructor, while allowing a sub-array to be specified.
Note that if the sequence of characters is already available
within a character array, using this constructor is faster than
converting the char array to string and using the
BigDecimal(String) constructor .
Translates a character array representation of a
BigDecimal into a
BigDecimal, accepting the
same sequence of characters as the
constructor, while allowing a sub-array to be specified and
with rounding according to the context settings.
Note that if the sequence of characters is already available
within a character array, using this constructor is faster than
converting the char array to string and using the
BigDecimal(String) constructor .
Translates a character array representation of a
BigDecimal into a
BigDecimal, accepting the
same sequence of characters as the
constructor.
Note that if the sequence of characters is already available
as a character array, using this constructor is faster than
converting the char array to string and using the
BigDecimal(String) constructor .
Translates a character array representation of a
BigDecimal into a
BigDecimal, accepting the
same sequence of characters as the
constructor and with rounding according to the context
settings.
Note that if the sequence of characters is already available
as a character array, using this constructor is faster than
converting the char array to string and using the
BigDecimal(String) constructor .
Translates the string representation of a
BigDecimal
into a
BigDecimal. The string representation consists
of an optional sign,
'+' (
'\u002B') or
'-' (
'\u002D'), followed by a sequence of
zero or more decimal digits ("the integer"), optionally
followed by a fraction, optionally followed by an exponent.
The fraction consists of a decimal point followed by zero
or more decimal digits. The string must contain at least one
digit in either the integer or the fraction. The number formed
by the sign, the integer and the fraction is referred to as the
significand.
The exponent consists of the character 'e'
('\u0075') or 'E' ('\u0045')
followed by one or more decimal digits. The value of the
exponent must lie between -Integer#MAX_VALUE
(Integer#MIN_VALUE
+1) and Integer#MAX_VALUE
, inclusive.
More formally, the strings this constructor accepts are
described by the following grammar:
- BigDecimalString:
- Signopt Significand Exponentopt
- Sign:
- +
- -
- Significand:
- IntegerPart . FractionPartopt
- . FractionPart
- IntegerPart
- IntegerPart:
- Digits
- FractionPart:
- Digits
- Exponent:
- ExponentIndicator SignedInteger
- ExponentIndicator:
- e
- E
- SignedInteger:
- Signopt Digits
- Digits:
- Digit
- Digits Digit
- Digit:
- any character for which Character#isDigit
returns true, including 0, 1, 2 ...
The scale of the returned BigDecimal will be the
number of digits in the fraction, or zero if the string
contains no decimal point, subject to adjustment for any
exponent; if the string contains an exponent, the exponent is
subtracted from the scale. The value of the resulting scale
must lie between Integer.MIN_VALUE and
Integer.MAX_VALUE, inclusive.
The character-to-digit mapping is provided by java.lang.Character#digit
set to convert to radix 10. The
String may not contain any extraneous characters (whitespace,
for example).
Examples:
The value of the returned BigDecimal is equal to
significand × 10 exponent.
For each string on the left, the resulting representation
[BigInteger, scale] is shown on the right.
"0" [0,0]
"0.00" [0,2]
"123" [123,0]
"-123" [-123,0]
"1.23E3" [123,-1]
"1.23E+3" [123,-1]
"12.3E+7" [123,-6]
"12.0" [120,1]
"12.3" [123,1]
"0.00123" [123,5]
"-1.23E-12" [-123,14]
"1234.5E-4" [12345,5]
"0E+7" [0,-7]
"-0" [0,0]
Note: For values other than float and
double NaN and ±Infinity, this constructor is
compatible with the values returned by Float#toString
and Double#toString
. This is generally the preferred
way to convert a float or double into a
BigDecimal, as it doesn't suffer from the unpredictability of
the
constructor.
Translates the string representation of a
BigDecimal
into a
BigDecimal, accepting the same strings as the
constructor, with rounding
according to the context settings.
Translates a
double into a
BigDecimal which
is the exact decimal representation of the
double's
binary floating-point value. The scale of the returned
BigDecimal is the smallest value such that
(10scale × val) is an integer.
Notes:
-
The results of this constructor can be somewhat unpredictable.
One might assume that writing new BigDecimal(0.1) in
Java creates a BigDecimal which is exactly equal to
0.1 (an unscaled value of 1, with a scale of 1), but it is
actually equal to
0.1000000000000000055511151231257827021181583404541015625.
This is because 0.1 cannot be represented exactly as a
double (or, for that matter, as a binary fraction of
any finite length). Thus, the value that is being passed
in to the constructor is not exactly equal to 0.1,
appearances notwithstanding.
-
The String constructor, on the other hand, is
perfectly predictable: writing new BigDecimal("0.1")
creates a BigDecimal which is exactly equal to
0.1, as one would expect. Therefore, it is generally
recommended that the be used in preference to this one.
-
When a double must be used as a source for a
BigDecimal, note that this constructor provides an
exact conversion; it does not give the same result as
converting the double to a String using the
method and then using the
constructor. To get that result,
use the static
method.
Translates a
double into a
BigDecimal, with
rounding according to the context settings. The scale of the
BigDecimal is the smallest value such that
(10scale × val) is an integer.
The results of this constructor can be somewhat unpredictable
and its use is generally not recommended; see the notes under
the
constructor.
Translates a BigInteger into a BigDecimal.
The scale of the BigDecimal is zero.
Translates a BigInteger into a BigDecimal
rounding according to the context settings. The scale of the
BigDecimal is zero.
Translates a BigInteger unscaled value and an
int scale into a BigDecimal. The value of
the BigDecimal is
(unscaledVal × 10-scale).
Translates a BigInteger unscaled value and an
int scale into a BigDecimal, with rounding
according to the context settings. The value of the
BigDecimal is (unscaledVal ×
10-scale), rounded according to the
precision and rounding mode settings.
Translates an int into a BigDecimal. The
scale of the BigDecimal is zero.
Translates an int into a BigDecimal, with
rounding according to the context settings. The scale of the
BigDecimal, before any rounding, is zero.
Translates a long into a BigDecimal. The
scale of the BigDecimal is zero.
Translates a long into a BigDecimal, with
rounding according to the context settings. The scale of the
BigDecimal, before any rounding, is zero.
The value 1, with a scale of 0.
Rounding mode to round towards positive infinity. If the
BigDecimal is positive, behaves as for
ROUND_UP; if negative, behaves as for
ROUND_DOWN. Note that this rounding mode never
decreases the calculated value.
Rounding mode to round towards zero. Never increments the digit
prior to a discarded fraction (i.e., truncates). Note that this
rounding mode never increases the magnitude of the calculated value.
Rounding mode to round towards negative infinity. If the
BigDecimal is positive, behave as for
ROUND_DOWN; if negative, behave as for
ROUND_UP. Note that this rounding mode never
increases the calculated value.
Rounding mode to round towards "nearest neighbor"
unless both neighbors are equidistant, in which case round
down. Behaves as for ROUND_UP if the discarded
fraction is > 0.5; otherwise, behaves as for
ROUND_DOWN.
Rounding mode to round towards the "nearest neighbor"
unless both neighbors are equidistant, in which case, round
towards the even neighbor. Behaves as for
ROUND_HALF_UP if the digit to the left of the
discarded fraction is odd; behaves as for
ROUND_HALF_DOWN if it's even. Note that this is the
rounding mode that minimizes cumulative error when applied
repeatedly over a sequence of calculations.
Rounding mode to round towards "nearest neighbor"
unless both neighbors are equidistant, in which case round up.
Behaves as for ROUND_UP if the discarded fraction is
>= 0.5; otherwise, behaves as for ROUND_DOWN. Note
that this is the rounding mode that most of us were taught in
grade school.
Rounding mode to assert that the requested operation has an exact
result, hence no rounding is necessary. If this rounding mode is
specified on an operation that yields an inexact result, an
ArithmeticException is thrown.
Rounding mode to round away from zero. Always increments the
digit prior to a nonzero discarded fraction. Note that this rounding
mode never decreases the magnitude of the calculated value.
The value 10, with a scale of 0.
The value 0, with a scale of 0.
Returns a BigDecimal whose value is the absolute value
of this BigDecimal, and whose scale is
this.scale().
Returns a BigDecimal whose value is the absolute value
of this BigDecimal, with rounding according to the
context settings.
Returns a BigDecimal whose value is (this +
augend), and whose scale is max(this.scale(),
augend.scale()).
Returns a BigDecimal whose value is (this + augend),
with rounding according to the context settings.
If either number is zero and the precision setting is nonzero then
the other number, rounded if necessary, is used as the result.
Returns the value of the specified number as a byte.
This may involve rounding or truncation.
Converts this BigDecimal to a byte, checking
for lost information. If this BigDecimal has a
nonzero fractional part or is out of the possible range for a
byte result then an ArithmeticException is
thrown.
Compares this BigDecimal with the specified
BigDecimal. Two BigDecimal objects that are
equal in value but have a different scale (like 2.0 and 2.00)
are considered equal by this method. This method is provided
in preference to individual methods for each of the six boolean
comparison operators (<, ==, >, >=, !=, <=). The
suggested idiom for performing these comparisons is:
(x.compareTo(y) <op> 0), where
<op> is one of the six comparison operators.
Compares this object with the specified object for order. Returns a
negative integer, zero, or a positive integer as this object is less
than, equal to, or greater than the specified object.
In the foregoing description, the notation
sgn(expression) designates the mathematical
signum function, which is defined to return one of -1,
0, or 1 according to whether the value of expression
is negative, zero or positive.
The implementor must ensure sgn(x.compareTo(y)) ==
-sgn(y.compareTo(x)) for all x and y. (This
implies that x.compareTo(y) must throw an exception iff
y.compareTo(x) throws an exception.)
The implementor must also ensure that the relation is transitive:
(x.compareTo(y)>0 && y.compareTo(z)>0) implies
x.compareTo(z)>0.
Finally, the implementer must ensure that x.compareTo(y)==0
implies that sgn(x.compareTo(z)) == sgn(y.compareTo(z)), for
all z.
It is strongly recommended, but not strictly required that
(x.compareTo(y)==0) == (x.equals(y)). Generally speaking, any
class that implements the Comparable interface and violates
this condition should clearly indicate this fact. The recommended
language is "Note: this class has a natural ordering that is
inconsistent with equals."
Returns a BigDecimal whose value is (this /
divisor), and whose preferred scale is (this.scale() -
divisor.scale()); if the exact quotient cannot be
represented (because it has a non-terminating decimal
expansion) an ArithmeticException is thrown.
Returns a
BigDecimal whose value is
(this /
divisor), and whose scale is
this.scale(). If
rounding must be performed to generate a result with the given
scale, the specified rounding mode is applied.
The new
method
should be used in preference to this legacy method.
Returns a
BigDecimal whose value is
(this /
divisor), and whose scale is as specified. If rounding must
be performed to generate a result with the specified scale, the
specified rounding mode is applied.
The new
method
should be used in preference to this legacy method.
Returns a BigDecimal whose value is (this /
divisor), and whose scale is as specified. If rounding must
be performed to generate a result with the specified scale, the
specified rounding mode is applied.
Returns a BigDecimal whose value is (this /
divisor), with rounding according to the context settings.
Returns a BigDecimal whose value is (this /
divisor), and whose scale is this.scale(). If
rounding must be performed to generate a result with the given
scale, the specified rounding mode is applied.
Returns a two-element
BigDecimal array containing the
result of
divideToIntegralValue followed by the result of
remainder on the two operands.
Note that if both the integer quotient and remainder are
needed, this method is faster than using the
divideToIntegralValue and remainder methods
separately because the division need only be carried out once.
Returns a two-element
BigDecimal array containing the
result of
divideToIntegralValue followed by the result of
remainder on the two operands calculated with rounding
according to the context settings.
Note that if both the integer quotient and remainder are
needed, this method is faster than using the
divideToIntegralValue and remainder methods
separately because the division need only be carried out once.
Returns a BigDecimal whose value is the integer part
of the quotient (this / divisor) rounded down. The
preferred scale of the result is (this.scale() -
divisor.scale()).
Returns a BigDecimal whose value is the integer part
of (this / divisor). Since the integer part of the
exact quotient does not depend on the rounding mode, the
rounding mode does not affect the values returned by this
method. The preferred scale of the result is
(this.scale() - divisor.scale()). An
ArithmeticException is thrown if the integer part of
the exact quotient needs more than mc.precision
digits.
Compares this
BigDecimal with the specified
Object for equality. Unlike
compareTo
, this method considers two
BigDecimal objects equal only if they are equal in
value and scale (thus 2.0 is not equal to 2.00 when compared by
this method).
Returns the runtime class of an object. That Class
object is the object that is locked by static synchronized
methods of the represented class.
Returns the hash code for this BigDecimal. Note that
two BigDecimal objects that are numerically equal but
differ in scale (like 2.0 and 2.00) will generally not
have the same hash code.
Converts this
BigDecimal to an
int. This
conversion is analogous to a
narrowing
primitive conversion from
double to
short as defined in the
Java Language
Specification: any fractional part of this
BigDecimal will be discarded, and if the resulting
"
BigInteger" is too big to fit in an
int, only the low-order 32 bits are returned.
Note that this conversion can lose information about the
overall magnitude and precision of this
BigDecimal
value as well as return a result with the opposite sign.
Converts this BigDecimal to an int, checking
for lost information. If this BigDecimal has a
nonzero fractional part or is out of the possible range for an
int result then an ArithmeticException is
thrown.
Converts this
BigDecimal to a
long. This
conversion is analogous to a
narrowing
primitive conversion from
double to
short as defined in the
Java Language
Specification: any fractional part of this
BigDecimal will be discarded, and if the resulting
"
BigInteger" is too big to fit in a
long, only the low-order 64 bits are returned.
Note that this conversion can lose information about the
overall magnitude and precision of this
BigDecimal value as well
as return a result with the opposite sign.
Converts this BigDecimal to a long, checking
for lost information. If this BigDecimal has a
nonzero fractional part or is out of the possible range for a
long result then an ArithmeticException is
thrown.
Returns the maximum of this BigDecimal and val.
Returns the minimum of this BigDecimal and
val.
Returns a BigDecimal which is equivalent to this one
with the decimal point moved n places to the left. If
n is non-negative, the call merely adds n to
the scale. If n is negative, the call is equivalent
to movePointRight(-n). The BigDecimal
returned by this call has value (this ×
10-n) and scale max(this.scale()+n,
0).
Returns a BigDecimal which is equivalent to this one
with the decimal point moved n places to the right.
If n is non-negative, the call merely subtracts
n from the scale. If n is negative, the call
is equivalent to movePointLeft(-n). The
BigDecimal returned by this call has value (this
× 10n) and scale max(this.scale()-n,
0).
Returns a BigDecimal whose value is (this ×
multiplicand), and whose scale is (this.scale() +
multiplicand.scale()).
Returns a BigDecimal whose value is (this ×
multiplicand), with rounding according to the context settings.
Returns a BigDecimal whose value is (-this),
and whose scale is this.scale().
Returns a BigDecimal whose value is (-this),
with rounding according to the context settings.
Wakes up a single thread that is waiting on this object's
monitor. If any threads are waiting on this object, one of them
is chosen to be awakened. The choice is arbitrary and occurs at
the discretion of the implementation. A thread waits on an object's
monitor by calling one of the
wait methods.
The awakened thread will not be able to proceed until the current
thread relinquishes the lock on this object. The awakened thread will
compete in the usual manner with any other threads that might be
actively competing to synchronize on this object; for example, the
awakened thread enjoys no reliable privilege or disadvantage in being
the next thread to lock this object.
This method should only be called by a thread that is the owner
of this object's monitor. A thread becomes the owner of the
object's monitor in one of three ways:
- By executing a synchronized instance method of that object.
- By executing the body of a
synchronized statement
that synchronizes on the object.
- For objects of type
Class, by executing a
synchronized static method of that class.
Only one thread at a time can own an object's monitor.
Wakes up all threads that are waiting on this object's monitor. A
thread waits on an object's monitor by calling one of the
wait methods.
The awakened threads will not be able to proceed until the current
thread relinquishes the lock on this object. The awakened threads
will compete in the usual manner with any other threads that might
be actively competing to synchronize on this object; for example,
the awakened threads enjoy no reliable privilege or disadvantage in
being the next thread to lock this object.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
Returns a
BigDecimal whose value is
(+this), and whose
scale is
this.scale().
This method, which simply returns this BigDecimal
is included for symmetry with the unary minus method
.
Returns a
BigDecimal whose value is
(+this),
with rounding according to the context settings.
The effect of this method is identical to that of the
method.
Returns a
BigDecimal whose value is
(thisn), The power is computed exactly, to
unlimited precision.
The parameter n must be in the range 0 through
999999999, inclusive. ZERO.pow(0) returns #ONE
.
Note that future releases may expand the allowable exponent
range of this method.
Returns a
BigDecimal whose value is
(thisn). The current implementation uses
the core algorithm defined in ANSI standard X3.274-1996 with
rounding according to the context settings. In general, the
returned numerical value is within two ulps of the exact
numerical value for the chosen precision. Note that future
releases may use a different algorithm with a decreased
allowable error bound and increased allowable exponent range.
The X3.274-1996 algorithm is:
- An ArithmeticException exception is thrown if
- abs(n) > 999999999
- mc.precision == 0 and n < 0
- mc.precision > 0 and n has more than
mc.precision decimal digits
- if n is zero, #ONE
is returned even if
this is zero, otherwise
- if n is positive, the result is calculated via
the repeated squaring technique into a single accumulator.
The individual multiplications with the accumulator use the
same math context settings as in mc except for a
precision increased to mc.precision + elength + 1
where elength is the number of decimal digits in
n.
- if n is negative, the result is calculated as if
n were positive; this value is then divided into one
using the working precision specified above.
- The final value from either the positive or negative case
is then rounded to the destination precision.
Returns the
precision of this
BigDecimal. (The
precision is the number of digits in the unscaled value.)
The precision of a zero value is 1.
Returns a
BigDecimal whose value is
(this % divisor).
The remainder is given by
this.subtract(this.divideToIntegralValue(divisor).multiply(divisor)).
Note that this is not the modulo operation (the result can be
negative).
Returns a
BigDecimal whose value is
(this %
divisor), with rounding according to the context settings.
The
MathContext settings affect the implicit divide
used to compute the remainder. The remainder computation
itself is by definition exact. Therefore, the remainder may
contain more than
mc.getPrecision() digits.
The remainder is given by
this.subtract(this.divideToIntegralValue(divisor,
mc).multiply(divisor)). Note that this is not the modulo
operation (the result can be negative).
Returns a
BigDecimal rounded according to the
MathContext settings. If the precision setting is 0 then
no rounding takes place.
The effect of this method is identical to that of the
method.
Returns the scale of this BigDecimal. If zero
or positive, the scale is the number of digits to the right of
the decimal point. If negative, the unscaled value of the
number is multiplied by ten to the power of the negation of the
scale. For example, a scale of -3 means the unscaled
value is multiplied by 1000.
Returns a BigDecimal whose numerical value is equal to
(this * 10n). The scale of
the result is (this.scale() - n).
Returns a
BigDecimal whose scale is the specified
value, and whose value is numerically equal to this
BigDecimal's. Throws an
ArithmeticException
if this is not possible.
This call is typically used to increase the scale, in which
case it is guaranteed that there exists a BigDecimal
of the specified scale and the correct value. The call can
also be used to reduce the scale if the caller knows that the
BigDecimal has sufficiently many zeros at the end of
its fractional part (i.e., factors of ten in its integer value)
to allow for the rescaling without changing its value.
This method returns the same result as the two-argument
versions of setScale, but saves the caller the trouble
of specifying a rounding mode in cases where it is irrelevant.
Note that since BigDecimal objects are immutable,
calls of this method do not result in the original
object being modified, contrary to the usual convention of
having methods named setX mutate field
X. Instead, setScale returns an
object with the proper scale; the returned object may or may
not be newly allocated.
Returns a
BigDecimal whose scale is the specified
value, and whose unscaled value is determined by multiplying or
dividing this
BigDecimal's unscaled value by the
appropriate power of ten to maintain its overall value. If the
scale is reduced by the operation, the unscaled value must be
divided (rather than multiplied), and the value may be changed;
in this case, the specified rounding mode is applied to the
division.
Note that since BigDecimal objects are immutable, calls of
this method do not result in the original object being
modified, contrary to the usual convention of having methods
named setX mutate field X.
Instead, setScale returns an object with the proper
scale; the returned object may or may not be newly allocated.
The new
method should
be used in preference to this legacy method.
Returns a BigDecimal whose scale is the specified
value, and whose unscaled value is determined by multiplying or
dividing this BigDecimal's unscaled value by the
appropriate power of ten to maintain its overall value. If the
scale is reduced by the operation, the unscaled value must be
divided (rather than multiplied), and the value may be changed;
in this case, the specified rounding mode is applied to the
division.
Returns the value of the specified number as a short.
This may involve rounding or truncation.
Converts this BigDecimal to a short, checking
for lost information. If this BigDecimal has a
nonzero fractional part or is out of the possible range for a
short result then an ArithmeticException is
thrown.
Returns the signum function of this BigDecimal.
Returns a BigDecimal which is numerically equal to
this one but with any trailing zeros removed from the
representation. For example, stripping the trailing zeros from
the BigDecimal value 600.0, which has
[BigInteger, scale] components equals to
[6000, 1], yields 6E2 with [BigInteger,
scale] components equals to [6, -2]
Returns a BigDecimal whose value is (this -
subtrahend), and whose scale is max(this.scale(),
subtrahend.scale()).
Returns a BigDecimal whose value is (this - subtrahend),
with rounding according to the context settings.
If subtrahend is zero then this, rounded if necessary, is used as the
result. If this is zero then the result is subtrahend.negate(mc).
Converts this
BigDecimal to a
BigInteger.
This conversion is analogous to a
narrowing
primitive conversion from
double to
long as defined in the
Java Language
Specification: any fractional part of this
BigDecimal will be discarded. Note that this
conversion can lose information about the precision of the
BigDecimal value.
To have an exception thrown if the conversion is inexact (in
other words if a nonzero fractional part is discarded), use the
method.
Converts this BigDecimal to a BigInteger,
checking for lost information. An exception is thrown if this
BigDecimal has a nonzero fractional part.
Returns a string representation of this
BigDecimal,
using engineering notation if an exponent is needed.
Returns a string that represents the BigDecimal as
described in the
method, except that if
exponential notation is used, the power of ten is adjusted to
be a multiple of three (engineering notation) such that the
integer part of nonzero values will be in the range 1 through
999. If exponential notation is used for zero values, a
decimal point and one or two fractional zero digits are used so
that the scale of the zero value is preserved. Note that
unlike the output of
, the output of this
method is not guaranteed to recover the same [integer,
scale] pair of this BigDecimal if the output string is
converting back to a BigDecimal using the . The result of this method meets
the weaker constraint of always producing a numerically equal
result from applying the string constructor to the method's output.
Returns a string representation of this BigDecimal
without an exponent field. For values with a positive scale,
the number of digits to the right of the decimal point is used
to indicate scale. For values with a zero or negative scale,
the resulting string is generated as if the value were
converted to a numerically equal value with zero scale and as
if all the trailing zeros of the zero scale value were present
in the result.
The entire string is prefixed by a minus sign character '-'
('\u002D') if the unscaled value is less than
zero. No sign character is prefixed if the unscaled value is
zero or positive.
Note that if the result of this method is passed to the
, only the
numerical value of this BigDecimal will necessarily be
recovered; the representation of the new BigDecimal
may have a different scale. In particular, if this
BigDecimal has a positive scale, the string resulting
from this method will have a scale of zero when processed by
the string constructor.
(This method behaves analogously to the toString
method in 1.4 and earlier releases.)
Returns the string representation of this
BigDecimal,
using scientific notation if an exponent is needed.
A standard canonical string form of the BigDecimal
is created as though by the following steps: first, the
absolute value of the unscaled value of the BigDecimal
is converted to a string in base ten using the characters
'0' through '9' with no leading zeros (except
if its value is zero, in which case a single '0'
character is used).
Next, an adjusted exponent is calculated; this is the
negated scale, plus the number of characters in the converted
unscaled value, less one. That is,
-scale+(ulength-1), where ulength is the
length of the absolute value of the unscaled value in decimal
digits (its precision).
If the scale is greater than or equal to zero and the
adjusted exponent is greater than or equal to -6, the
number will be converted to a character form without using
exponential notation. In this case, if the scale is zero then
no decimal point is added and if the scale is positive a
decimal point will be inserted with the scale specifying the
number of characters to the right of the decimal point.
'0' characters are added to the left of the converted
unscaled value as necessary. If no character precedes the
decimal point after this insertion then a conventional
'0' character is prefixed.
Otherwise (that is, if the scale is negative, or the
adjusted exponent is less than -6), the number will be
converted to a character form using exponential notation. In
this case, if the converted BigInteger has more than
one digit a decimal point is inserted after the first digit.
An exponent in character form is then suffixed to the converted
unscaled value (perhaps with inserted decimal point); this
comprises the letter 'E' followed immediately by the
adjusted exponent converted to a character form. The latter is
in base ten, using the characters '0' through
'9' with no leading zeros, and is always prefixed by a
sign character '-' ('\u002D') if the
adjusted exponent is negative, '+'
('\u002B') otherwise).
Finally, the entire string is prefixed by a minus sign
character '-' ('\u002D') if the unscaled
value is less than zero. No sign character is prefixed if the
unscaled value is zero or positive.
Examples:
For each representation [unscaled value, scale]
on the left, the resulting string is shown on the right.
[123,0] "123"
[-123,0] "-123"
[123,-1] "1.23E+3"
[123,-3] "1.23E+5"
[123,1] "12.3"
[123,5] "0.00123"
[123,10] "1.23E-8"
[-123,12] "-1.23E-10"
Notes:
- There is a one-to-one mapping between the distinguishable
BigDecimal values and the result of this conversion.
That is, every distinguishable BigDecimal value
(unscaled value and scale) has a unique string representation
as a result of using toString. If that string
representation is converted back to a BigDecimal using
the
constructor, then the original
value will be recovered.
- The string produced for a given number is always the same;
it is not affected by locale. This means that it can be used
as a canonical string representation for exchanging decimal
data, or as a key for a Hashtable, etc. Locale-sensitive
number formatting and parsing is handled by the java.text.NumberFormat
class and its subclasses.
- The #toEngineeringString
method may be used for
presenting numbers with exponents in engineering notation, and the
setScale
method may be used for
rounding a BigDecimal so it has a known number of digits after
the decimal point.
- The digit-to-character mapping provided by
Character.forDigit is used.
Returns the size of an ulp, a unit in the last place, of this
BigDecimal. An ulp of a nonzero BigDecimal
value is the positive distance between this value and the
BigDecimal value next larger in magnitude with the
same number of digits. An ulp of a zero value is numerically
equal to 1 with the scale of this. The result is
stored with the same scale as this so the result
for zero and nonzero values is equal to [1,
this.scale()].
Returns a BigInteger whose value is the unscaled
value of this BigDecimal. (Computes (this *
10this.scale()).)
Translates a
double into a
BigDecimal, using
the
double's canonical string representation provided
by the
method.
Note: This is generally the preferred way to convert
a double (or float) into a
BigDecimal, as the value returned is equal to that
resulting from constructing a BigDecimal from the
result of using
.
Translates a long value into a BigDecimal
with a scale of zero. This "static factory method"
is provided in preference to a (long) constructor
because it allows for reuse of frequently used
BigDecimal values.
Translates a long unscaled value and an
int scale into a BigDecimal. This
"static factory method" is provided in preference to
a (long, int) constructor because it
allows for reuse of frequently used BigDecimal values..
Causes current thread to wait until another thread invokes the
method or the
method for this object.
In other words, this method behaves exactly as if it simply
performs the call
wait(0).
The current thread must own this object's monitor. The thread
releases ownership of this monitor and waits until another thread
notifies threads waiting on this object's monitor to wake up
either through a call to the notify method or the
notifyAll method. The thread then waits until it can
re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are
possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait();
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the
notify method for a
description of the ways in which a thread can become the owner of
a monitor.
Causes current thread to wait until either another thread invokes the
method or the
method for this object, or a
specified amount of time has elapsed.
The current thread must own this object's monitor.
This method causes the current thread (call it T) to
place itself in the wait set for this object and then to relinquish
any and all synchronization claims on this object. Thread T
becomes disabled for thread scheduling purposes and lies dormant
until one of four things happens:
- Some other thread invokes the notify method for this
object and thread T happens to be arbitrarily chosen as
the thread to be awakened.
- Some other thread invokes the notifyAll method for this
object.
- Some other thread interrupts
thread T.
- The specified amount of real time has elapsed, more or less. If
timeout is zero, however, then real time is not taken into
consideration and the thread simply waits until notified.
The thread
T is then removed from the wait set for this
object and re-enabled for thread scheduling. It then competes in the
usual manner with other threads for the right to synchronize on the
object; once it has gained control of the object, all its
synchronization claims on the object are restored to the status quo
ante - that is, to the situation as of the time that the
wait
method was invoked. Thread
T then returns from the
invocation of the
wait method. Thus, on return from the
wait method, the synchronization state of the object and of
thread
T is exactly as it was when the
wait method
was invoked.
A thread can also wake up without being notified, interrupted, or
timing out, a so-called spurious wakeup. While this will rarely
occur in practice, applications must guard against it by testing for
the condition that should have caused the thread to be awakened, and
continuing to wait if the condition is not satisfied. In other words,
waits should always occur in loops, like this one:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout);
... // Perform action appropriate to condition
}
(For more information on this topic, see Section 3.2.3 in Doug Lea's
"Concurrent Programming in Java (Second Edition)" (Addison-Wesley,
2000), or Item 50 in Joshua Bloch's "Effective Java Programming
Language Guide" (Addison-Wesley, 2001).
If the current thread is
interrupted
by another thread
while it is waiting, then an InterruptedException is thrown.
This exception is not thrown until the lock status of this object has
been restored as described above.
Note that the wait method, as it places the current thread
into the wait set for this object, unlocks only this object; any
other objects on which the current thread may be synchronized remain
locked while the thread waits.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
Causes current thread to wait until another thread invokes the
method or the
method for this object, or
some other thread interrupts the current thread, or a certain
amount of real time has elapsed.
This method is similar to the wait method of one
argument, but it allows finer control over the amount of time to
wait for a notification before giving up. The amount of real time,
measured in nanoseconds, is given by:
1000000*timeout+nanos
In all other respects, this method does the same thing as the
method
of one argument. In particular,
wait(0, 0) means the same thing as wait(0).
The current thread must own this object's monitor. The thread
releases ownership of this monitor and waits until either of the
following two conditions has occurred:
- Another thread notifies threads waiting on this object's monitor
to wake up either through a call to the
notify method
or the notifyAll method.
- The timeout period, specified by
timeout
milliseconds plus nanos nanoseconds arguments, has
elapsed.
The thread then waits until it can re-obtain ownership of the
monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are
possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout, nanos);
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the
notify method for a
description of the ways in which a thread can become the owner of
a monitor.