Added in API level 1

RoundingMode

class RoundingMode
kotlin.Any
   ↳ kotlin.Enum<java.math.RoundingMode>
   ↳ java.math.RoundingMode

Specifies a rounding policy for numerical operations capable of discarding precision. Each rounding mode indicates how the least significant returned digit of a rounded result is to be calculated. If fewer digits are returned than the digits needed to represent the exact numerical result, the discarded digits will be referred to as the discarded fraction regardless the digits' contribution to the value of the number. In other words, considered as a numerical value, the discarded fraction could have an absolute value greater than one.

Each rounding mode description includes a table listing how different two-digit decimal values would round to a one digit decimal value under the rounding mode in question. The result column in the tables could be gotten by creating a BigDecimal number with the specified value, forming a MathContext object with the proper settings (precision set to 1, and the roundingMode set to the rounding mode in question), and calling round on this number with the proper MathContext. A summary table showing the results of these rounding operations for all rounding modes appears below.

Summary of Rounding Operations Under Different Rounding Modes
Input Number Result of rounding input to one digit with the given rounding mode
UP DOWN CEILING FLOOR HALF_UP HALF_DOWN HALF_EVEN UNNECESSARY
5.5 6 5 6 5 6 5 6 throw ArithmeticException
2.5 3 2 3 2 3 2 2 throw ArithmeticException
1.6 2 1 2 1 2 2 2 throw ArithmeticException
1.1 2 1 2 1 1 1 1 throw ArithmeticException
1.0 1 1 1 1 1 1 1 1
-1.0 -1 -1 -1 -1 -1 -1 -1 -1
-1.1 -2 -1 -1 -2 -1 -1 -1 throw ArithmeticException
-1.6 -2 -1 -1 -2 -2 -2 -2 throw ArithmeticException
-2.5 -3 -2 -2 -3 -3 -2 -2 throw ArithmeticException
-5.5 -6 -5 -5 -6 -6 -5 -6 throw ArithmeticException

This enum is intended to replace the integer-based enumeration of rounding mode constants in BigDecimal (BigDecimal#ROUND_UP, BigDecimal#ROUND_DOWN, etc. ).

Summary

Enum values

Rounding mode to round towards positive infinity.

Rounding mode to round towards zero.

Rounding mode to round towards negative infinity.

Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round down.

Rounding mode to round towards the "nearest neighbor" unless both neighbors are equidistant, in which case, round towards the even neighbor.

Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round up.

Rounding mode to assert that the requested operation has an exact result, hence no rounding is necessary.

Rounding mode to round away from zero.
Public methods
static RoundingMode!
valueOf(rm: Int)

Returns the RoundingMode object corresponding to a legacy integer rounding mode constant in BigDecimal.

Enum values

CEILING

Added in API level 1
enum val CEILING : RoundingMode

Rounding mode to round towards positive infinity. If the result is positive, behaves as for RoundingMode.UP; if negative, behaves as for RoundingMode.DOWN. Note that this rounding mode never decreases the calculated value. This mode corresponds to the IEEE 754-2019 rounding-direction attribute roundTowardPositive.

Example:

Rounding mode CEILING Examples
Input Number Input rounded to one digit
with CEILING rounding
5.5 6
2.5 3
1.6 2
1.1 2
1.0 1
-1.0 -1
-1.1 -1
-1.6 -1
-2.5 -2
-5.5 -5

DOWN

Added in API level 1
enum val DOWN : RoundingMode

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. This mode corresponds to the IEEE 754-2019 rounding-direction attribute roundTowardZero.

Example:

Rounding mode DOWN Examples
Input Number Input rounded to one digit
with DOWN rounding
5.5 5
2.5 2
1.6 1
1.1 1
1.0 1
-1.0 -1
-1.1 -1
-1.6 -1
-2.5 -2
-5.5 -5

FLOOR

Added in API level 1
enum val FLOOR : RoundingMode

Rounding mode to round towards negative infinity. If the result is positive, behave as for RoundingMode.DOWN; if negative, behave as for RoundingMode.UP. Note that this rounding mode never increases the calculated value. This mode corresponds to the IEEE 754-2019 rounding-direction attribute roundTowardNegative.

Example:

Rounding mode FLOOR Examples
Input Number Input rounded to one digit
with FLOOR rounding
5.5 5
2.5 2
1.6 1
1.1 1
1.0 1
-1.0 -1
-1.1 -2
-1.6 -2
-2.5 -3
-5.5 -6

HALF_DOWN

Added in API level 1
enum val HALF_DOWN : RoundingMode

Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round down. Behaves as for RoundingMode.UP if the discarded fraction is > 0.5; otherwise, behaves as for RoundingMode.DOWN.

Example:

Rounding mode HALF_DOWN Examples
Input Number Input rounded to one digit
with HALF_DOWN rounding
5.5 5
2.5 2
1.6 2
1.1 1
1.0 1
-1.0 -1
-1.1 -1
-1.6 -2
-2.5 -2
-5.5 -5

HALF_EVEN

Added in API level 1
enum val HALF_EVEN : RoundingMode

Rounding mode to round towards the "nearest neighbor" unless both neighbors are equidistant, in which case, round towards the even neighbor. Behaves as for RoundingMode.HALF_UP if the digit to the left of the discarded fraction is odd; behaves as for RoundingMode.HALF_DOWN if it's even. Note that this is the rounding mode that statistically minimizes cumulative error when applied repeatedly over a sequence of calculations. It is sometimes known as "Banker's rounding," and is chiefly used in the USA. This rounding mode is analogous to the rounding policy used for float and double arithmetic in Java. This mode corresponds to the IEEE 754-2019 rounding-direction attribute roundTiesToEven.

Example:

Rounding mode HALF_EVEN Examples
Input Number Input rounded to one digit
with HALF_EVEN rounding
5.5 6
2.5 2
1.6 2
1.1 1
1.0 1
-1.0 -1
-1.1 -1
-1.6 -2
-2.5 -2
-5.5 -6

HALF_UP

Added in API level 1
enum val HALF_UP : RoundingMode

Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round up. Behaves as for RoundingMode.UP if the discarded fraction is ≥ 0.5; otherwise, behaves as for RoundingMode.DOWN. Note that this is the rounding mode commonly taught at school. This mode corresponds to the IEEE 754-2019 rounding-direction attribute roundTiesToAway.

Example:

Rounding mode HALF_UP Examples
Input Number Input rounded to one digit
with HALF_UP rounding
5.5 6
2.5 3
1.6 2
1.1 1
1.0 1
-1.0 -1
-1.1 -1
-1.6 -2
-2.5 -3
-5.5 -6

UNNECESSARY

Added in API level 1
enum val UNNECESSARY : RoundingMode

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.

Example:

Rounding mode UNNECESSARY Examples
Input Number Input rounded to one digit
with UNNECESSARY rounding
5.5 throw ArithmeticException
2.5 throw ArithmeticException
1.6 throw ArithmeticException
1.1 throw ArithmeticException
1.0 1
-1.0 -1
-1.1 throw ArithmeticException
-1.6 throw ArithmeticException
-2.5 throw ArithmeticException
-5.5 throw ArithmeticException

UP

Added in API level 1
enum val UP : RoundingMode

Rounding mode to round away from zero. Always increments the digit prior to a non-zero discarded fraction. Note that this rounding mode never decreases the magnitude of the calculated value.

Example:

Rounding mode UP Examples
Input Number Input rounded to one digit
with UP rounding
5.5 6
2.5 3
1.6 2
1.1 2
1.0 1
-1.0 -1
-1.1 -2
-1.6 -2
-2.5 -3
-5.5 -6

Public methods

valueOf

Added in API level 1
static fun valueOf(rm: Int): RoundingMode!

Returns the RoundingMode object corresponding to a legacy integer rounding mode constant in BigDecimal.

Parameters
rm Int: legacy integer rounding mode to convert
Return
RoundingMode! RoundingMode corresponding to the given integer.
Exceptions
java.lang.IllegalArgumentException integer is out of range