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public final enum

RoundingMode

extends Enum<E extends Enum<E>>

java.lang.Object
↳	java.lang.Enum<E extends java.lang.Enum<E>>
	↳	java.math.RoundingMode

Class Overview

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 (ROUND_UP, ROUND_DOWN, etc. ).

Summary

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

Public Methods
static RoundingMode	valueOf(int rm) Returns the `RoundingMode` object corresponding to a legacy integer rounding mode constant in `BigDecimal`.
static RoundingMode	valueOf(String name)
final static RoundingMode[]	values()

[Expand]

Inherited Methods

From class java.lang.Enum

final Object	clone() Throws CloneNotSupportedException.
final int	compareTo(E o) Compares this enum with the specified object for order.
final boolean	equals(Object other) Returns true if the specified object is equal to this enum constant.
final void	finalize() enum classes cannot have finalize methods.
final Class<E>	getDeclaringClass() Returns the Class object corresponding to this enum constant's enum type.
final int	hashCode() Returns a hash code for this enum constant.
final String	name() Returns the name of this enum constant, exactly as declared in its enum declaration.
final int	ordinal() Returns the ordinal of this enumeration constant (its position in its enum declaration, where the initial constant is assigned an ordinal of zero).
String	toString() Returns the name of this enum constant, as contained in the declaration.
static <T extends Enum<T>> T	valueOf(Class<T> enumType, String name) Returns the enum constant of the specified enum type with the specified name.

From class java.lang.Object

Object	clone() Creates and returns a copy of this object.
boolean	equals(Object obj) Indicates whether some other object is "equal to" this one.
void	finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
final Class<?>	getClass() Returns the runtime class of this `Object`.
int	hashCode() Returns a hash code value for the object.
final void	notify() Wakes up a single thread that is waiting on this object's monitor.
final void	notifyAll() Wakes up all threads that are waiting on this object's monitor.
String	toString() Returns a string representation of the object.
final void	wait() Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object.
final void	wait(long timeout, int nanos) Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
final void	wait(long timeout) Causes the current thread to wait until either another thread invokes the `notify()` method or the `notifyAll()` method for this object, or a specified amount of time has elapsed.

From interface java.lang.Comparable

Enum Values

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:

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

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:

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

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:

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

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:

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

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:

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

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:

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

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:

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`

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:

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

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

Classes

Enums

RoundingMode

Class Overview

Summary of Rounding Operations Under Different Rounding Modes

See Also

Summary

Enum Values

public static final RoundingMode CEILING

public static final RoundingMode DOWN

public static final RoundingMode FLOOR

public static final RoundingMode HALF_DOWN

public static final RoundingMode HALF_EVEN

public static final RoundingMode HALF_UP

public static final RoundingMode UNNECESSARY

public static final RoundingMode UP

Public Methods

public static RoundingMode valueOf (int rm)

Parameters

Returns

Throws

public static RoundingMode valueOf (String name)

public static final RoundingMode[] values ()