Movatterモバイル変換

Enum RoundingMode

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

All Implemented Interfaces:: Serializable,Comparable<RoundingMode>

public enumRoundingModeextendsEnum<RoundingMode>

Specifies arounding 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 thediscarded 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 aBigDecimal number with the specified value, forming aMathContext object with the proper settings (precision set to1, and theroundingMode set to the rounding mode in question), and callinground on this number with the properMathContext. 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`

Thisenum is intended to replace the integer-based enumeration of rounding mode constants inBigDecimal (BigDecimal.ROUND_UP,BigDecimal.ROUND_DOWN, etc. ).

Since:: 1.5
See Also:: BigDecimal,MathContext

Enum Constant Summary

Enum Constants
Enum Constant	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	Description
`staticRoundingMode`	`valueOf(int rm)`	Returns the`RoundingMode` object corresponding to a legacy integer rounding mode constant in`BigDecimal`.
`staticRoundingMode`	`valueOf(String name)`	Returns the enum constant of this type with the specified name.
`staticRoundingMode[]`	`values()`	Returns an array containing the constants of this enum type, inthe order they are declared.

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

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

Enum Constant Detail

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
withUP 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

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
withDOWN 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

CEILING
```
public static final RoundingMode CEILING
```
Rounding mode to round towards positive infinity. If the result is positive, behaves as forRoundingMode.UP; if negative, behaves as forRoundingMode.DOWN. Note that this rounding mode never decreases the calculated value.
Example:
Rounding mode CEILING Examples
Input Number Input rounded to one digit
withCEILING 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

FLOOR
```
public static final RoundingMode FLOOR
```
Rounding mode to round towards negative infinity. If the result is positive, behave as forRoundingMode.DOWN; if negative, behave as forRoundingMode.UP. Note that this rounding mode never increases the calculated value.
Example:
Rounding mode FLOOR Examples
Input Number Input rounded to one digit
withFLOOR 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_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 forRoundingMode.UP if the discarded fraction is ≥ 0.5; otherwise, behaves as forRoundingMode.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
withHALF_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

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 forRoundingMode.UP if the discarded fraction is > 0.5; otherwise, behaves as forRoundingMode.DOWN.
Example:
Rounding mode HALF_DOWN Examples
Input Number Input rounded to one digit
withHALF_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 forRoundingMode.HALF_UP if the digit to the left of the discarded fraction is odd; behaves as forRoundingMode.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 forfloat anddouble arithmetic in Java.
Example:
Rounding mode HALF_EVEN Examples
Input Number Input rounded to one digit
withHALF_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

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, anArithmeticException 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`

Method Detail
- values
```
public static RoundingMode[] values()
```
  Returns an array containing the constants of this enum type, inthe order they are declared. This method may be used to iterateover 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
- valueOf
```
public static RoundingMode valueOf(String name)
```
  Returns the enum constant of this type with the specified name.The string must matchexactly an identifier used to declare anenum 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
- valueOf
```
public static RoundingMode valueOf(int rm)
```
  Returns theRoundingMode object corresponding to a legacy integer rounding mode constant inBigDecimal.
  Parameters:
  rm - legacy integer rounding mode to convert
  Returns:
  RoundingMode corresponding to the given integer.
  Throws:
  IllegalArgumentException - integer is out of range

Movatterモバイル変換

Enum RoundingMode

Enum Constant Summary

Method Summary

Methods inherited from class java.lang.Enum

Methods inherited from class java.lang.Object

Enum Constant Detail

UP

DOWN

CEILING

FLOOR

HALF_UP

HALF_DOWN

HALF_EVEN

UNNECESSARY

Method Detail

values

valueOf

valueOf