com.ibm.icu.math
public final class MathContext extends Object implements Serializable
MathContext
immutable class encapsulates the
settings understood by the operator methods of the BigDecimal
class (and potentially other classes). Operator methods are those
that effect an operation on a number or a pair of numbers.
The settings, which are not base-dependent, comprise:
digits
:
the number of digits (precision) to be used for an operation
form
:
the form of any exponent that results from the operation
lostDigits
:
whether checking for lost digits is enabled
roundingMode
:
the algorithm to be used for rounding.
When provided, a MathContext
object supplies the
settings for an operation directly.
When MathContext.DEFAULT
is provided for a
MathContext
parameter then the default settings are used
(9, SCIENTIFIC, false, ROUND_HALF_UP
).
In the BigDecimal
class, all methods which accept a
MathContext
object defaults) also have a version of the
method which does not accept a MathContext parameter. These versions
carry out unlimited precision fixed point arithmetic (as though the
settings were (0, PLAIN, false, ROUND_HALF_UP
).
The instance variables are shared with default access (so they are
directly accessible to the BigDecimal
class), but must
never be changed.
The rounding mode constants have the same names and values as the
constants of the same name in java.math.BigDecimal
, to
maintain compatibility with earlier versions of
BigDecimal
.
See Also: BigDecimal
UNKNOWN: ICU 2.0
Field Summary | |
---|---|
static MathContext | DEFAULT
A MathContext object initialized to the default
settings for general-purpose arithmetic. |
static int | ENGINEERING
Standard floating point notation (with engineering exponential
format, where the power of ten is a multiple of 3).
|
static int | PLAIN
Plain (fixed point) notation, without any exponent.
|
static int | ROUND_CEILING
Rounding mode to round to a more positive number.
|
static int | ROUND_DOWN
Rounding mode to round towards zero.
|
static int | ROUND_FLOOR
Rounding mode to round to a more negative number.
|
static int | ROUND_HALF_DOWN
Rounding mode to round to nearest neighbor, where an equidistant
value is rounded down.
|
static int | ROUND_HALF_EVEN
Rounding mode to round to nearest neighbor, where an equidistant
value is rounded to the nearest even neighbor.
|
static int | ROUND_HALF_UP
Rounding mode to round to nearest neighbor, where an equidistant
value is rounded up.
|
static int | ROUND_UNNECESSARY
Rounding mode to assert that no rounding is necessary.
|
static int | ROUND_UP
Rounding mode to round away from zero.
|
static int | SCIENTIFIC
Standard floating point notation (with scientific exponential
format, where there is one digit before any decimal point).
|
Constructor Summary | |
---|---|
MathContext(int setdigits)
Constructs a new MathContext with a specified
precision.
| |
MathContext(int setdigits, int setform)
Constructs a new MathContext with a specified
precision and form.
| |
MathContext(int setdigits, int setform, boolean setlostdigits)
Constructs a new MathContext with a specified
precision, form, and lostDigits setting.
| |
MathContext(int setdigits, int setform, boolean setlostdigits, int setroundingmode)
Constructs a new MathContext with a specified
precision, form, lostDigits, and roundingMode setting.
|
Method Summary | |
---|---|
int | getDigits()
Returns the digits setting.
|
int | getForm()
Returns the form setting.
|
boolean | getLostDigits()
Returns the lostDigits setting.
|
int | getRoundingMode()
Returns the roundingMode setting.
|
String | toString() Returns the MathContext as a readable string.
|
MathContext
object initialized to the default
settings for general-purpose arithmetic. That is,
digits=9 form=SCIENTIFIC lostDigits=false
roundingMode=ROUND_HALF_UP
.
See Also: SCIENTIFIC ROUND_HALF_UP
UNKNOWN: ICU 2.0
BigDecimal
operation.
A zero result in plain form may have a decimal part of one or
more zeros.
See Also: PLAIN SCIENTIFIC
UNKNOWN: ICU 2.0
BigDecimal
operation.
A zero result in plain form may have a decimal part of one or
more zeros.
See Also: ENGINEERING SCIENTIFIC
UNKNOWN: ICU 2.0
BigDecimal
operation.
If any of the discarded digits are non-zero then the result should be rounded towards the next more positive digit.
UNKNOWN: ICU 2.0
BigDecimal
operation.
All discarded digits are ignored (truncated). The result is neither incremented nor decremented.
UNKNOWN: ICU 2.0
BigDecimal
operation.
If any of the discarded digits are non-zero then the result should be rounded towards the next more negative digit.
UNKNOWN: ICU 2.0
BigDecimal
operation.
If the discarded digits represent greater than half (0.5 times) the value of a one in the next position then the result should be rounded up (away from zero). Otherwise the discarded digits are ignored.
UNKNOWN: ICU 2.0
BigDecimal
operation.
If the discarded digits represent greater than half (0.5 times) the value of a one in the next position then the result should be rounded up (away from zero). If they represent less than half, then the result should be rounded down.
Otherwise (they represent exactly half) the result is rounded down if its rightmost digit is even, or rounded up if its rightmost digit is odd (to make an even digit).
UNKNOWN: ICU 2.0
BigDecimal
operation.
If the discarded digits represent greater than or equal to half (0.5 times) the value of a one in the next position then the result should be rounded up (away from zero). Otherwise the discarded digits are ignored.
UNKNOWN: ICU 2.0
BigDecimal
operation.
Rounding (potential loss of information) is not permitted.
If any of the discarded digits are non-zero then an
ArithmeticException
should be thrown.
UNKNOWN: ICU 2.0
BigDecimal
operation.
If any of the discarded digits are non-zero then the result will be rounded up (away from zero).
UNKNOWN: ICU 2.0
BigDecimal
operation.
A zero result in plain form may have a decimal part of one or
more zeros.
See Also: ENGINEERING PLAIN
UNKNOWN: ICU 2.0
MathContext
with a specified
precision.
The other settings are set to the default values
(see DEFAULT).
An IllegalArgumentException
is thrown if the
setdigits
parameter is out of range
(<0 or >999999999).
Parameters: setdigits The int
digits setting
for this MathContext
.
Throws: IllegalArgumentException parameter out of range.
UNKNOWN: ICU 2.0
MathContext
with a specified
precision and form.
The other settings are set to the default values
(see DEFAULT).
An IllegalArgumentException
is thrown if the
setdigits
parameter is out of range
(<0 or >999999999), or if the value given for the
setform
parameter is not one of the appropriate
constants.
Parameters: setdigits The int
digits setting
for this MathContext
. setform The int
form setting
for this MathContext
.
Throws: IllegalArgumentException parameter out of range.
UNKNOWN: ICU 2.0
MathContext
with a specified
precision, form, and lostDigits setting.
The roundingMode setting is set to its default value
(see DEFAULT).
An IllegalArgumentException
is thrown if the
setdigits
parameter is out of range
(<0 or >999999999), or if the value given for the
setform
parameter is not one of the appropriate
constants.
Parameters: setdigits The int
digits setting
for this MathContext
. setform The int
form setting
for this MathContext
. setlostdigits The boolean
lostDigits
setting for this MathContext
.
Throws: IllegalArgumentException parameter out of range.
UNKNOWN: ICU 2.0
MathContext
with a specified
precision, form, lostDigits, and roundingMode setting.
An IllegalArgumentException
is thrown if the
setdigits
parameter is out of range
(<0 or >999999999), or if the value given for the
setform
or setroundingmode
parameters is
not one of the appropriate constants.
Parameters: setdigits The int
digits setting
for this MathContext
. setform The int
form setting
for this MathContext
. setlostdigits The boolean
lostDigits
setting for this MathContext
. setroundingmode The int
roundingMode setting
for this MathContext
.
Throws: IllegalArgumentException parameter out of range.
UNKNOWN: ICU 2.0
Returns: an int
which is the value of the digits
setting
UNKNOWN: ICU 2.0
Returns: an int
which is the value of the form setting
UNKNOWN: ICU 2.0
true
(enabled) or
false
(disabled).
Returns: a boolean
which is the value of the lostDigits
setting
UNKNOWN: ICU 2.0
Returns: an int
which is the value of the roundingMode
setting
UNKNOWN: ICU 2.0
MathContext
as a readable string.
The String
returned represents the settings of the
MathContext
object as four blank-delimited words
separated by a single blank and with no leading or trailing blanks,
as follows:
digits=
, immediately followed by
the value of the digits setting as a numeric word.
form=
, immediately followed by
the value of the form setting as an uppercase word
(one of SCIENTIFIC
, PLAIN
, or
ENGINEERING
).
lostDigits=
, immediately followed by
the value of the lostDigits setting
(1
if enabled, 0
if disabled).
roundingMode=
, immediately followed by
the value of the roundingMode setting as a word.
This word will be the same as the name of the corresponding public
constant.
For example:
digits=9 form=SCIENTIFIC lostDigits=0 roundingMode=ROUND_HALF_UP
Additional words may be appended to the result of
toString
in the future if more properties are added
to the class.
Returns: a String
representing the context settings.
UNKNOWN: ICU 2.0