RoundingMode

java.lang.Object
- java.lang.Enum<RoundingMode>
- - java.math.RoundingMode

All Implemented Interfaces:: Serializable, Comparable<RoundingMode>

public enum RoundingMode
extends Enum<RoundingMode>

Specifies a rounding behavior 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**
	Result of rounding input to one digit with the given rounding mode
Input Number	`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. ).

Since:: 1.5
Author:: Josh Bloch, Mike Cowlishaw, Joseph D. Darcy
See Also:: BigDecimal, MathContext

Enum Constant Summary

Enum Constants
Enum Constant and Description
`CEILING` Rounding mode to round towards positive infinity.
`DOWN` Rounding mode to round towards zero.
`FLOOR` Rounding mode to round towards negative infinity.
`HALF_DOWN` Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round down.
`HALF_EVEN` Rounding mode to round towards the "nearest neighbor" unless both neighbors are equidistant, in which case, round towards the even neighbor.
`HALF_UP` Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round up.
`UNNECESSARY` Rounding mode to assert that the requested operation has an exact result, hence no rounding is necessary.
`UP` Rounding mode to round away from zero.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static RoundingMode`	`valueOf(int rm)` Returns the `RoundingMode` object corresponding to a legacy integer rounding mode constant in `BigDecimal`.
`static RoundingMode`	`valueOf(String name)` Returns the enum constant of this type with the specified name.
`static RoundingMode[]`	`values()` Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum
compareTo, equals, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object
clone, getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

CEILING
```
public static final RoundingMode CEILING
```
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.
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

**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
```
public static final RoundingMode DOWN
```
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.
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

**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
```
public static final RoundingMode FLOOR
```
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.
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

**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
```
public static final RoundingMode HALF_DOWN
```
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

**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
```
public static final RoundingMode HALF_EVEN
```
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.
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

**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
```
public static final RoundingMode HALF_UP
```
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.
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

**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

public static final RoundingMode UNNECESSARY

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
```
public static final RoundingMode UP
```
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

**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

Method Detail
- valueOf
```
public static RoundingMode valueOf(int rm)
```
  Returns the RoundingMode object corresponding to a legacy integer rounding mode constant in BigDecimal.
  
  Parameters:
  
  rm - legacy integer rounding mode to convert
  
  Returns:
  
  RoundingMode corresponding to the given integer.
  
  Throws:
  
  IllegalArgumentException - integer is out of range
- valueOf
```
public static RoundingMode valueOf(String name)
```
  Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
  
  Parameters:
  
  name - the name of the enum constant to be returned.
  
  Returns:
  
  the enum constant with the specified name
  
  Throws:
  
  IllegalArgumentException - if this enum type has no constant with the specified name
  
  NullPointerException - if the argument is null
- values
```
public static RoundingMode[] values()
```
  Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:
```
for (RoundingMode c : RoundingMode.values())
    System.out.println(c);
```
  Returns:
  
  an array containing the constants of this enum type, in the order they are declared

Enum RoundingMode

Enum Constant Summary

Method Summary

Methods inherited from class java.lang.Enum

Methods inherited from class java.lang.Object

Enum Constant Detail

CEILING

DOWN

FLOOR

HALF_DOWN

HALF_EVEN

HALF_UP

UNNECESSARY

UP

Method Detail

valueOf

valueOf

values