jaroslav@1258: /*
jaroslav@1258: * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
jaroslav@1258: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jaroslav@1258: *
jaroslav@1258: * This code is free software; you can redistribute it and/or modify it
jaroslav@1258: * under the terms of the GNU General Public License version 2 only, as
jaroslav@1258: * published by the Free Software Foundation. Oracle designates this
jaroslav@1258: * particular file as subject to the "Classpath" exception as provided
jaroslav@1258: * by Oracle in the LICENSE file that accompanied this code.
jaroslav@1258: *
jaroslav@1258: * This code is distributed in the hope that it will be useful, but WITHOUT
jaroslav@1258: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jaroslav@1258: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
jaroslav@1258: * version 2 for more details (a copy is included in the LICENSE file that
jaroslav@1258: * accompanied this code).
jaroslav@1258: *
jaroslav@1258: * You should have received a copy of the GNU General Public License version
jaroslav@1258: * 2 along with this work; if not, write to the Free Software Foundation,
jaroslav@1258: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jaroslav@1258: *
jaroslav@1258: * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jaroslav@1258: * or visit www.oracle.com if you need additional information or have any
jaroslav@1258: * questions.
jaroslav@1258: */
jaroslav@1258:
jaroslav@1258: /*
jaroslav@1258: * Portions Copyright IBM Corporation, 2001. All Rights Reserved.
jaroslav@1258: */
jaroslav@1258: package java.math;
jaroslav@1258:
jaroslav@1258: /**
jaroslav@1258: * Specifies a rounding behavior for numerical operations
jaroslav@1258: * capable of discarding precision. Each rounding mode indicates how
jaroslav@1258: * the least significant returned digit of a rounded result is to be
jaroslav@1258: * calculated. If fewer digits are returned than the digits needed to
jaroslav@1258: * represent the exact numerical result, the discarded digits will be
jaroslav@1258: * referred to as the discarded fraction regardless the digits'
jaroslav@1258: * contribution to the value of the number. In other words,
jaroslav@1258: * considered as a numerical value, the discarded fraction could have
jaroslav@1258: * an absolute value greater than one.
jaroslav@1258: *
jaroslav@1258: * Each rounding mode description includes a table listing how
jaroslav@1258: * different two-digit decimal values would round to a one digit
jaroslav@1258: * decimal value under the rounding mode in question. The result
jaroslav@1258: * column in the tables could be gotten by creating a
jaroslav@1258: * {@code BigDecimal} number with the specified value, forming a
jaroslav@1258: * {@link MathContext} object with the proper settings
jaroslav@1258: * ({@code precision} set to {@code 1}, and the
jaroslav@1258: * {@code roundingMode} set to the rounding mode in question), and
jaroslav@1258: * calling {@link BigDecimal#round round} on this number with the
jaroslav@1258: * proper {@code MathContext}. A summary table showing the results
jaroslav@1258: * of these rounding operations for all rounding modes appears below.
jaroslav@1258: *
jaroslav@1258: *
jaroslav@1258: *
jaroslav@1258: * Summary of Rounding Operations Under Different Rounding Modes
jaroslav@1258: * | Result of rounding input to one digit with the given
jaroslav@1258: * rounding mode |
jaroslav@1258: *
|---|
jaroslav@1258: * | Input Number | {@code UP} |
jaroslav@1258: * {@code DOWN} |
jaroslav@1258: * {@code CEILING} |
jaroslav@1258: * {@code FLOOR} |
jaroslav@1258: * {@code HALF_UP} |
jaroslav@1258: * {@code HALF_DOWN} |
jaroslav@1258: * {@code HALF_EVEN} |
jaroslav@1258: * {@code UNNECESSARY} |
jaroslav@1258: *
jaroslav@1258: *
| 5.5 | 6 | 5 | 6 | 5 | 6 | 5 | 6 | throw {@code ArithmeticException} |
jaroslav@1258: *
| 2.5 | 3 | 2 | 3 | 2 | 3 | 2 | 2 | throw {@code ArithmeticException} |
jaroslav@1258: *
| 1.6 | 2 | 1 | 2 | 1 | 2 | 2 | 2 | throw {@code ArithmeticException} |
jaroslav@1258: *
| 1.1 | 2 | 1 | 2 | 1 | 1 | 1 | 1 | throw {@code ArithmeticException} |
jaroslav@1258: *
| 1.0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
jaroslav@1258: *
| -1.0 | -1 | -1 | -1 | -1 | -1 | -1 | -1 | -1 |
jaroslav@1258: *
| -1.1 | -2 | -1 | -1 | -2 | -1 | -1 | -1 | throw {@code ArithmeticException} |
jaroslav@1258: *
| -1.6 | -2 | -1 | -1 | -2 | -2 | -2 | -2 | throw {@code ArithmeticException} |
jaroslav@1258: *
| -2.5 | -3 | -2 | -2 | -3 | -3 | -2 | -2 | throw {@code ArithmeticException} |
jaroslav@1258: *
| -5.5 | -6 | -5 | -5 | -6 | -6 | -5 | -6 | throw {@code ArithmeticException} |
jaroslav@1258: *
jaroslav@1258: *
jaroslav@1258: *
jaroslav@1258: * This {@code enum} is intended to replace the integer-based
jaroslav@1258: * enumeration of rounding mode constants in {@link BigDecimal}
jaroslav@1258: * ({@link BigDecimal#ROUND_UP}, {@link BigDecimal#ROUND_DOWN},
jaroslav@1258: * etc. ).
jaroslav@1258: *
jaroslav@1258: * @see BigDecimal
jaroslav@1258: * @see MathContext
jaroslav@1258: * @author Josh Bloch
jaroslav@1258: * @author Mike Cowlishaw
jaroslav@1258: * @author Joseph D. Darcy
jaroslav@1258: * @since 1.5
jaroslav@1258: */
jaroslav@1258: public enum RoundingMode {
jaroslav@1258:
jaroslav@1258: /**
jaroslav@1258: * Rounding mode to round away from zero. Always increments the
jaroslav@1258: * digit prior to a non-zero discarded fraction. Note that this
jaroslav@1258: * rounding mode never decreases the magnitude of the calculated
jaroslav@1258: * value.
jaroslav@1258: *
jaroslav@1258: *
Example:
jaroslav@1258: *
jaroslav@1258: *| Input Number |
jaroslav@1258: * Input rounded to one digit
with {@code UP} rounding
jaroslav@1258: * |
|---|
| 5.5 | 6 |
jaroslav@1258: *
| 2.5 | 3 |
jaroslav@1258: *
| 1.6 | 2 |
jaroslav@1258: *
| 1.1 | 2 |
jaroslav@1258: *
| 1.0 | 1 |
jaroslav@1258: *
| -1.0 | -1 |
jaroslav@1258: *
| -1.1 | -2 |
jaroslav@1258: *
| -1.6 | -2 |
jaroslav@1258: *
| -2.5 | -3 |
jaroslav@1258: *
| -5.5 | -6 |
jaroslav@1258: *
jaroslav@1258: */
jaroslav@1258: UP(BigDecimal.ROUND_UP),
jaroslav@1258:
jaroslav@1258: /**
jaroslav@1258: * Rounding mode to round towards zero. Never increments the digit
jaroslav@1258: * prior to a discarded fraction (i.e., truncates). Note that this
jaroslav@1258: * rounding mode never increases the magnitude of the calculated value.
jaroslav@1258: *
jaroslav@1258: *Example:
jaroslav@1258: *
jaroslav@1258: *| Input Number |
jaroslav@1258: * Input rounded to one digit
with {@code DOWN} rounding
jaroslav@1258: * |
|---|
| 5.5 | 5 |
jaroslav@1258: *
| 2.5 | 2 |
jaroslav@1258: *
| 1.6 | 1 |
jaroslav@1258: *
| 1.1 | 1 |
jaroslav@1258: *
| 1.0 | 1 |
jaroslav@1258: *
| -1.0 | -1 |
jaroslav@1258: *
| -1.1 | -1 |
jaroslav@1258: *
| -1.6 | -1 |
jaroslav@1258: *
| -2.5 | -2 |
jaroslav@1258: *
| -5.5 | -5 |
jaroslav@1258: *
jaroslav@1258: */
jaroslav@1258: DOWN(BigDecimal.ROUND_DOWN),
jaroslav@1258:
jaroslav@1258: /**
jaroslav@1258: * Rounding mode to round towards positive infinity. If the
jaroslav@1258: * result is positive, behaves as for {@code RoundingMode.UP};
jaroslav@1258: * if negative, behaves as for {@code RoundingMode.DOWN}. Note
jaroslav@1258: * that this rounding mode never decreases the calculated value.
jaroslav@1258: *
jaroslav@1258: *Example:
jaroslav@1258: *
jaroslav@1258: *| Input Number |
jaroslav@1258: * Input rounded to one digit
with {@code CEILING} rounding
jaroslav@1258: * |
|---|
| 5.5 | 6 |
jaroslav@1258: *
| 2.5 | 3 |
jaroslav@1258: *
| 1.6 | 2 |
jaroslav@1258: *
| 1.1 | 2 |
jaroslav@1258: *
| 1.0 | 1 |
jaroslav@1258: *
| -1.0 | -1 |
jaroslav@1258: *
| -1.1 | -1 |
jaroslav@1258: *
| -1.6 | -1 |
jaroslav@1258: *
| -2.5 | -2 |
jaroslav@1258: *
| -5.5 | -5 |
jaroslav@1258: *
jaroslav@1258: */
jaroslav@1258: CEILING(BigDecimal.ROUND_CEILING),
jaroslav@1258:
jaroslav@1258: /**
jaroslav@1258: * Rounding mode to round towards negative infinity. If the
jaroslav@1258: * result is positive, behave as for {@code RoundingMode.DOWN};
jaroslav@1258: * if negative, behave as for {@code RoundingMode.UP}. Note that
jaroslav@1258: * this rounding mode never increases the calculated value.
jaroslav@1258: *
jaroslav@1258: *Example:
jaroslav@1258: *
jaroslav@1258: *| Input Number |
jaroslav@1258: * Input rounded to one digit
with {@code FLOOR} rounding
jaroslav@1258: * |
|---|
| 5.5 | 5 |
jaroslav@1258: *
| 2.5 | 2 |
jaroslav@1258: *
| 1.6 | 1 |
jaroslav@1258: *
| 1.1 | 1 |
jaroslav@1258: *
| 1.0 | 1 |
jaroslav@1258: *
| -1.0 | -1 |
jaroslav@1258: *
| -1.1 | -2 |
jaroslav@1258: *
| -1.6 | -2 |
jaroslav@1258: *
| -2.5 | -3 |
jaroslav@1258: *
| -5.5 | -6 |
jaroslav@1258: *
jaroslav@1258: */
jaroslav@1258: FLOOR(BigDecimal.ROUND_FLOOR),
jaroslav@1258:
jaroslav@1258: /**
jaroslav@1258: * Rounding mode to round towards {@literal "nearest neighbor"}
jaroslav@1258: * unless both neighbors are equidistant, in which case round up.
jaroslav@1258: * Behaves as for {@code RoundingMode.UP} if the discarded
jaroslav@1258: * fraction is ≥ 0.5; otherwise, behaves as for
jaroslav@1258: * {@code RoundingMode.DOWN}. Note that this is the rounding
jaroslav@1258: * mode commonly taught at school.
jaroslav@1258: *
jaroslav@1258: *Example:
jaroslav@1258: *
jaroslav@1258: *| Input Number |
jaroslav@1258: * Input rounded to one digit
with {@code HALF_UP} rounding
jaroslav@1258: * |
|---|
| 5.5 | 6 |
jaroslav@1258: *
| 2.5 | 3 |
jaroslav@1258: *
| 1.6 | 2 |
jaroslav@1258: *
| 1.1 | 1 |
jaroslav@1258: *
| 1.0 | 1 |
jaroslav@1258: *
| -1.0 | -1 |
jaroslav@1258: *
| -1.1 | -1 |
jaroslav@1258: *
| -1.6 | -2 |
jaroslav@1258: *
| -2.5 | -3 |
jaroslav@1258: *
| -5.5 | -6 |
jaroslav@1258: *
jaroslav@1258: */
jaroslav@1258: HALF_UP(BigDecimal.ROUND_HALF_UP),
jaroslav@1258:
jaroslav@1258: /**
jaroslav@1258: * Rounding mode to round towards {@literal "nearest neighbor"}
jaroslav@1258: * unless both neighbors are equidistant, in which case round
jaroslav@1258: * down. Behaves as for {@code RoundingMode.UP} if the discarded
jaroslav@1258: * fraction is > 0.5; otherwise, behaves as for
jaroslav@1258: * {@code RoundingMode.DOWN}.
jaroslav@1258: *
jaroslav@1258: *Example:
jaroslav@1258: *
jaroslav@1258: *| Input Number |
jaroslav@1258: * Input rounded to one digit
with {@code HALF_DOWN} rounding
jaroslav@1258: * |
|---|
| 5.5 | 5 |
jaroslav@1258: *
| 2.5 | 2 |
jaroslav@1258: *
| 1.6 | 2 |
jaroslav@1258: *
| 1.1 | 1 |
jaroslav@1258: *
| 1.0 | 1 |
jaroslav@1258: *
| -1.0 | -1 |
jaroslav@1258: *
| -1.1 | -1 |
jaroslav@1258: *
| -1.6 | -2 |
jaroslav@1258: *
| -2.5 | -2 |
jaroslav@1258: *
| -5.5 | -5 |
jaroslav@1258: *
jaroslav@1258: */
jaroslav@1258: HALF_DOWN(BigDecimal.ROUND_HALF_DOWN),
jaroslav@1258:
jaroslav@1258: /**
jaroslav@1258: * Rounding mode to round towards the {@literal "nearest neighbor"}
jaroslav@1258: * unless both neighbors are equidistant, in which case, round
jaroslav@1258: * towards the even neighbor. Behaves as for
jaroslav@1258: * {@code RoundingMode.HALF_UP} if the digit to the left of the
jaroslav@1258: * discarded fraction is odd; behaves as for
jaroslav@1258: * {@code RoundingMode.HALF_DOWN} if it's even. Note that this
jaroslav@1258: * is the rounding mode that statistically minimizes cumulative
jaroslav@1258: * error when applied repeatedly over a sequence of calculations.
jaroslav@1258: * It is sometimes known as {@literal "Banker's rounding,"} and is
jaroslav@1258: * chiefly used in the USA. This rounding mode is analogous to
jaroslav@1258: * the rounding policy used for {@code float} and {@code double}
jaroslav@1258: * arithmetic in Java.
jaroslav@1258: *
jaroslav@1258: *Example:
jaroslav@1258: *
jaroslav@1258: *| Input Number |
jaroslav@1258: * Input rounded to one digit
with {@code HALF_EVEN} rounding
jaroslav@1258: * |
|---|
| 5.5 | 6 |
jaroslav@1258: *
| 2.5 | 2 |
jaroslav@1258: *
| 1.6 | 2 |
jaroslav@1258: *
| 1.1 | 1 |
jaroslav@1258: *
| 1.0 | 1 |
jaroslav@1258: *
| -1.0 | -1 |
jaroslav@1258: *
| -1.1 | -1 |
jaroslav@1258: *
| -1.6 | -2 |
jaroslav@1258: *
| -2.5 | -2 |
jaroslav@1258: *
| -5.5 | -6 |
jaroslav@1258: *
jaroslav@1258: */
jaroslav@1258: HALF_EVEN(BigDecimal.ROUND_HALF_EVEN),
jaroslav@1258:
jaroslav@1258: /**
jaroslav@1258: * Rounding mode to assert that the requested operation has an exact
jaroslav@1258: * result, hence no rounding is necessary. If this rounding mode is
jaroslav@1258: * specified on an operation that yields an inexact result, an
jaroslav@1258: * {@code ArithmeticException} is thrown.
jaroslav@1258: *Example:
jaroslav@1258: *
jaroslav@1258: *| Input Number |
jaroslav@1258: * Input rounded to one digit
with {@code UNNECESSARY} rounding
jaroslav@1258: * |
|---|
| 5.5 | throw {@code ArithmeticException} |
jaroslav@1258: *
| 2.5 | throw {@code ArithmeticException} |
jaroslav@1258: *
| 1.6 | throw {@code ArithmeticException} |
jaroslav@1258: *
| 1.1 | throw {@code ArithmeticException} |
jaroslav@1258: *
| 1.0 | 1 |
jaroslav@1258: *
| -1.0 | -1 |
jaroslav@1258: *
| -1.1 | throw {@code ArithmeticException} |
jaroslav@1258: *
| -1.6 | throw {@code ArithmeticException} |
jaroslav@1258: *
| -2.5 | throw {@code ArithmeticException} |
jaroslav@1258: *
| -5.5 | throw {@code ArithmeticException} |
jaroslav@1258: *
jaroslav@1258: */
jaroslav@1258: UNNECESSARY(BigDecimal.ROUND_UNNECESSARY);
jaroslav@1258:
jaroslav@1258: // Corresponding BigDecimal rounding constant
jaroslav@1258: final int oldMode;
jaroslav@1258:
jaroslav@1258: /**
jaroslav@1258: * Constructor
jaroslav@1258: *
jaroslav@1258: * @param oldMode The {@code BigDecimal} constant corresponding to
jaroslav@1258: * this mode
jaroslav@1258: */
jaroslav@1258: private RoundingMode(int oldMode) {
jaroslav@1258: this.oldMode = oldMode;
jaroslav@1258: }
jaroslav@1258:
jaroslav@1258: /**
jaroslav@1258: * Returns the {@code RoundingMode} object corresponding to a
jaroslav@1258: * legacy integer rounding mode constant in {@link BigDecimal}.
jaroslav@1258: *
jaroslav@1258: * @param rm legacy integer rounding mode to convert
jaroslav@1258: * @return {@code RoundingMode} corresponding to the given integer.
jaroslav@1258: * @throws IllegalArgumentException integer is out of range
jaroslav@1258: */
jaroslav@1258: public static RoundingMode valueOf(int rm) {
jaroslav@1258: switch(rm) {
jaroslav@1258:
jaroslav@1258: case BigDecimal.ROUND_UP:
jaroslav@1258: return UP;
jaroslav@1258:
jaroslav@1258: case BigDecimal.ROUND_DOWN:
jaroslav@1258: return DOWN;
jaroslav@1258:
jaroslav@1258: case BigDecimal.ROUND_CEILING:
jaroslav@1258: return CEILING;
jaroslav@1258:
jaroslav@1258: case BigDecimal.ROUND_FLOOR:
jaroslav@1258: return FLOOR;
jaroslav@1258:
jaroslav@1258: case BigDecimal.ROUND_HALF_UP:
jaroslav@1258: return HALF_UP;
jaroslav@1258:
jaroslav@1258: case BigDecimal.ROUND_HALF_DOWN:
jaroslav@1258: return HALF_DOWN;
jaroslav@1258:
jaroslav@1258: case BigDecimal.ROUND_HALF_EVEN:
jaroslav@1258: return HALF_EVEN;
jaroslav@1258:
jaroslav@1258: case BigDecimal.ROUND_UNNECESSARY:
jaroslav@1258: return UNNECESSARY;
jaroslav@1258:
jaroslav@1258: default:
jaroslav@1258: throw new IllegalArgumentException("argument out of range");
jaroslav@1258: }
jaroslav@1258: }
jaroslav@1258: }