* <th>{@code DOWN} * <th>{@code CEILING} * <th>{@code FLOOR} * <th>{@code HALF_UP} * <th>{@code HALF_DOWN} * <th>{@code HALF_EVEN} * <th>{@code UNNECESSARY} * * <tr align=right> * <tr align=right> * <tr align=right> * <tr align=right> * <tr align=right> * <tr align=right> * <tr align=right> * <tr align=right> * <tr align=right> * <tr align=right> *</table> * * * <p>This {@code enum} is intended to replace the integer-based * enumeration of rounding mode constants in {@link BigDecimal} * ({@link BigDecimal#ROUND_UP}, {@link BigDecimal#ROUND_DOWN}, * etc. ). * * @see BigDecimal * @see MathContext * @author Josh Bloch * @author Mike Cowlishaw * @author Joseph D. Darcy * @since 1.5 */ public enum 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. * *<p>Example: *<table border> * <caption>Rounding mode UP Examples *<tr valign=top> * <th>Input rounded to one digit
with {@code UP} rounding *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *</table> */ UP(BigDecimal.ROUND_UP), /** * 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. * *<p>Example: *<table border> * <caption>Rounding mode DOWN Examples *<tr valign=top> * <th>Input rounded to one digit
with {@code DOWN} rounding *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *</table> */ DOWN(BigDecimal.ROUND_DOWN), /** * Rounding mode to round towards positive infinity. If the * result is positive, behaves as for {@code RoundingMode.UP}; * if negative, behaves as for {@code RoundingMode.DOWN}. Note * that this rounding mode never decreases the calculated value. * *<p>Example: *<table border> * <caption>Rounding mode CEILING Examples *<tr valign=top> * <th>Input rounded to one digit
with {@code CEILING} rounding *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *</table> */ CEILING(BigDecimal.ROUND_CEILING), /** * Rounding mode to round towards negative infinity. If the * result is positive, behave as for {@code RoundingMode.DOWN}; * if negative, behave as for {@code RoundingMode.UP}. Note that * this rounding mode never increases the calculated value. * *<p>Example: *<table border> * <caption>Rounding mode FLOOR Examples *<tr valign=top> * <th>Input rounded to one digit
with {@code FLOOR} rounding *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *</table> */ FLOOR(BigDecimal.ROUND_FLOOR), /** * Rounding mode to round towards {@literal "nearest neighbor"} * unless both neighbors are equidistant, in which case round up. * Behaves as for {@code RoundingMode.UP} if the discarded * fraction is ? 0.5; otherwise, behaves as for * {@code RoundingMode.DOWN}. Note that this is the rounding * mode commonly taught at school. * *<p>Example: *<table border> * <caption>Rounding mode HALF_UP Examples *<tr valign=top> * <th>Input rounded to one digit
with {@code HALF_UP} rounding *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *</table> */ HALF_UP(BigDecimal.ROUND_HALF_UP), /** * Rounding mode to round towards {@literal "nearest neighbor"} * unless both neighbors are equidistant, in which case round * down. Behaves as for {@code RoundingMode.UP} if the discarded * fraction is > 0.5; otherwise, behaves as for * {@code RoundingMode.DOWN}. * *<p>Example: *<table border> * <caption>Rounding mode HALF_DOWN Examples *<tr valign=top> * <th>Input rounded to one digit
with {@code HALF_DOWN} rounding *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *</table> */ HALF_DOWN(BigDecimal.ROUND_HALF_DOWN), /** * Rounding mode to round towards the {@literal "nearest neighbor"} * unless both neighbors are equidistant, in which case, round * towards the even neighbor. Behaves as for * {@code RoundingMode.HALF_UP} if the digit to the left of the * discarded fraction is odd; behaves as for * {@code 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 {@literal "Banker's rounding,"} and is * chiefly used in the USA. This rounding mode is analogous to * the rounding policy used for {@code float} and {@code double} * arithmetic in Java. * *<p>Example: *<table border> * <caption>Rounding mode HALF_EVEN Examples *<tr valign=top> * <th>Input rounded to one digit
with {@code HALF_EVEN} rounding *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *</table> */ HALF_EVEN(BigDecimal.ROUND_HALF_EVEN), /** * 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 * {@code ArithmeticException} is thrown. *<p>Example: *<table border> * <caption>Rounding mode UNNECESSARY Examples *<tr valign=top> * <th>Input rounded to one digit
with {@code UNNECESSARY} rounding *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *<tr align=right> *</table> */ UNNECESSARY(BigDecimal.ROUND_UNNECESSARY); // Corresponding BigDecimal rounding constant final int oldMode; /** * Constructor * * @param oldMode The {@code BigDecimal} constant corresponding to * this mode */ private RoundingMode(int oldMode) { this.oldMode = oldMode; } /** * Returns the {@code RoundingMode} object corresponding to a * legacy integer rounding mode constant in {@link BigDecimal}. * * @param rm legacy integer rounding mode to convert * @return {@code RoundingMode} corresponding to the given integer. * @throws IllegalArgumentException integer is out of range */ public static RoundingMode valueOf(int rm) { switch(rm) { case BigDecimal.ROUND_UP: return UP; case BigDecimal.ROUND_DOWN: return DOWN; case BigDecimal.ROUND_CEILING: return CEILING; case BigDecimal.ROUND_FLOOR: return FLOOR; case BigDecimal.ROUND_HALF_UP: return HALF_UP; case BigDecimal.ROUND_HALF_DOWN: return HALF_DOWN; case BigDecimal.ROUND_HALF_EVEN: return HALF_EVEN; case BigDecimal.ROUND_UNNECESSARY: return UNNECESSARY; default: throw new IllegalArgumentException("argument out of range"); } } }

	Java example source code file (RoundingMode.java) This example Java source code file (RoundingMode.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM. Learn more about this Java project at its project page. Java - Java tags/keywords ceiling, down, floor, half_down, half_even, half_up, illegalargumentexception, roundingmode, unnecessary The RoundingMode.java Java example source code /* * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /* * Portions Copyright IBM Corporation, 2001. All Rights Reserved. */ package java.math; /** * Specifies a <i>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 <i>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. * * <p>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 * {@code BigDecimal} number with the specified value, forming a * {@link MathContext} object with the proper settings * ({@code precision} set to {@code 1}, and the * {@code roundingMode} set to the rounding mode in question), and * calling {@link BigDecimal#round round} on this number with the * proper {@code MathContext}. A summary table showing the results * of these rounding operations for all rounding modes appears below. * *<table border> * <caption>Summary of Rounding Operations Under Different Rounding Modes * <tr>		Result of rounding input to one digit with the given * rounding mode</th> * <tr valign=top> * <th>Input Number								{@code UP}	5.5	6	5	6	5	6	5	6	throw {@code ArithmeticException}	2.5	3	2	3	2	3	2	2	throw {@code ArithmeticException}	1.6	2	1	2	1	2	2	2	throw {@code ArithmeticException}	1.1	2	1	2	1	1	1	1	throw {@code 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 {@code ArithmeticException}	-1.6	-2	-1	-1	-2	-2	-2	-2	throw {@code ArithmeticException}	-2.5	-3	-2	-2	-3	-3	-2	-2	throw {@code ArithmeticException}	-5.5	-6	-5	-5	-6	-6	-5	-6	throw {@code ArithmeticException}	Input Number	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	Input Number	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	Input Number	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	Input Number	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	Input Number	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	Input Number	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	Input Number	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	Input Number	5.5	throw {@code ArithmeticException}	2.5	throw {@code ArithmeticException}	1.6	throw {@code ArithmeticException}	1.1	throw {@code ArithmeticException}	1.0	1	-1.0	-1	-1.1	throw {@code ArithmeticException}	-1.6	throw {@code ArithmeticException}	-2.5	throw {@code ArithmeticException}	-5.5	throw {@code ArithmeticException}

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