/*

 * Portions Copyright 2003-2007 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.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</i> 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</i> 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.

 *

 *<p>

 *<table border>

 * <caption top><h3>Summary of Rounding Operations Under Different Rounding Modes</h3></caption>

 * <tr><th></th><th colspan=8>Result of rounding input to one digit with the given

 *                           rounding mode</th>

 * <tr valign=top>

 * <th>Input Number</th>         <th>{@code UP}</th>

 *                                           <th>{@code DOWN}</th>

 *                                                        <th>{@code CEILING}</th>

 *                                                                       <th>{@code FLOOR}</th>

 *                                                                                    <th>{@code HALF_UP}</th>

 *                                                                                                   <th>{@code HALF_DOWN}</th>

 *                                                                                                                    <th>{@code HALF_EVEN}</th>

 *                                                                                                                                     <th>{@code UNNECESSARY}</th>

 *

 * <tr align=right><td>5.5</td>  <td>6</td>  <td>5</td>    <td>6</td>    <td>5</td>  <td>6</td>      <td>5</td>       <td>6</td>       <td>throw {@code ArithmeticException}</td>

 * <tr align=right><td>2.5</td>  <td>3</td>  <td>2</td>    <td>3</td>    <td>2</td>  <td>3</td>      <td>2</td>       <td>2</td>       <td>throw {@code ArithmeticException}</td>

 * <tr align=right><td>1.6</td>  <td>2</td>  <td>1</td>    <td>2</td>    <td>1</td>  <td>2</td>      <td>2</td>       <td>2</td>       <td>throw {@code ArithmeticException}</td>

 * <tr align=right><td>1.1</td>  <td>2</td>  <td>1</td>    <td>2</td>    <td>1</td>  <td>1</td>      <td>1</td>       <td>1</td>       <td>throw {@code ArithmeticException}</td>

 * <tr align=right><td>1.0</td>  <td>1</td>  <td>1</td>    <td>1</td>    <td>1</td>  <td>1</td>      <td>1</td>       <td>1</td>       <td>1</td>

 * <tr align=right><td>-1.0</td> <td>-1</td> <td>-1</td>   <td>-1</td>   <td>-1</td> <td>-1</td>     <td>-1</td>      <td>-1</td>      <td>-1</td>

 * <tr align=right><td>-1.1</td> <td>-2</td> <td>-1</td>   <td>-1</td>   <td>-2</td> <td>-1</td>     <td>-1</td>      <td>-1</td>      <td>throw {@code ArithmeticException}</td>

 * <tr align=right><td>-1.6</td> <td>-2</td> <td>-1</td>   <td>-1</td>   <td>-2</td> <td>-2</td>     <td>-2</td>      <td>-2</td>      <td>throw {@code ArithmeticException}</td>

 * <tr align=right><td>-2.5</td> <td>-3</td> <td>-2</td>   <td>-2</td>   <td>-3</td> <td>-3</td>     <td>-2</td>      <td>-2</td>      <td>throw {@code ArithmeticException}</td>

 * <tr align=right><td>-5.5</td> <td>-6</td> <td>-5</td>   <td>-5</td>   <td>-6</td> <td>-6</td>     <td>-5</td>      <td>-6</td>      <td>throw {@code ArithmeticException}</td>

 *</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>

         *<tr valign=top><th>Input Number</th>

         *    <th>Input rounded to one digit<br> with {@code UP} rounding

         *<tr align=right><td>5.5</td>  <td>6</td>

         *<tr align=right><td>2.5</td>  <td>3</td>

         *<tr align=right><td>1.6</td>  <td>2</td>

         *<tr align=right><td>1.1</td>  <td>2</td>

         *<tr align=right><td>1.0</td>  <td>1</td>

         *<tr align=right><td>-1.0</td> <td>-1</td>

         *<tr align=right><td>-1.1</td> <td>-2</td>

         *<tr align=right><td>-1.6</td> <td>-2</td>

         *<tr align=right><td>-2.5</td> <td>-3</td>

         *<tr align=right><td>-5.5</td> <td>-6</td>

         *</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>

         *<tr valign=top><th>Input Number</th>

         *    <th>Input rounded to one digit<br> with {@code DOWN} rounding

         *<tr align=right><td>5.5</td>  <td>5</td>

         *<tr align=right><td>2.5</td>  <td>2</td>

         *<tr align=right><td>1.6</td>  <td>1</td>

         *<tr align=right><td>1.1</td>  <td>1</td>

         *<tr align=right><td>1.0</td>  <td>1</td>

         *<tr align=right><td>-1.0</td> <td>-1</td>

         *<tr align=right><td>-1.1</td> <td>-1</td>

         *<tr align=right><td>-1.6</td> <td>-1</td>

         *<tr align=right><td>-2.5</td> <td>-2</td>

         *<tr align=right><td>-5.5</td> <td>-5</td>

         *</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>

         *<tr valign=top><th>Input Number</th>

         *    <th>Input rounded to one digit<br> with {@code CEILING} rounding

         *<tr align=right><td>5.5</td>  <td>6</td>

         *<tr align=right><td>2.5</td>  <td>3</td>

         *<tr align=right><td>1.6</td>  <td>2</td>

         *<tr align=right><td>1.1</td>  <td>2</td>

         *<tr align=right><td>1.0</td>  <td>1</td>

         *<tr align=right><td>-1.0</td> <td>-1</td>

         *<tr align=right><td>-1.1</td> <td>-1</td>

         *<tr align=right><td>-1.6</td> <td>-1</td>

         *<tr align=right><td>-2.5</td> <td>-2</td>

         *<tr align=right><td>-5.5</td> <td>-5</td>

         *</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>

         *<tr valign=top><th>Input Number</th>

         *    <th>Input rounded to one digit<br> with {@code FLOOR} rounding

         *<tr align=right><td>5.5</td>  <td>5</td>

         *<tr align=right><td>2.5</td>  <td>2</td>

         *<tr align=right><td>1.6</td>  <td>1</td>

         *<tr align=right><td>1.1</td>  <td>1</td>

         *<tr align=right><td>1.0</td>  <td>1</td>

         *<tr align=right><td>-1.0</td> <td>-1</td>

         *<tr align=right><td>-1.1</td> <td>-2</td>

         *<tr align=right><td>-1.6</td> <td>-2</td>

         *<tr align=right><td>-2.5</td> <td>-3</td>

         *<tr align=right><td>-5.5</td> <td>-6</td>

         *</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>

         *<tr valign=top><th>Input Number</th>

         *    <th>Input rounded to one digit<br> with {@code HALF_UP} rounding

         *<tr align=right><td>5.5</td>  <td>6</td>

         *<tr align=right><td>2.5</td>  <td>3</td>

         *<tr align=right><td>1.6</td>  <td>2</td>

         *<tr align=right><td>1.1</td>  <td>1</td>

         *<tr align=right><td>1.0</td>  <td>1</td>

         *<tr align=right><td>-1.0</td> <td>-1</td>

         *<tr align=right><td>-1.1</td> <td>-1</td>

         *<tr align=right><td>-1.6</td> <td>-2</td>

         *<tr align=right><td>-2.5</td> <td>-3</td>

         *<tr align=right><td>-5.5</td> <td>-6</td>

         *</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>

         *<tr valign=top><th>Input Number</th>

         *    <th>Input rounded to one digit<br> with {@code HALF_DOWN} rounding

         *<tr align=right><td>5.5</td>  <td>5</td>

         *<tr align=right><td>2.5</td>  <td>2</td>

         *<tr align=right><td>1.6</td>  <td>2</td>

         *<tr align=right><td>1.1</td>  <td>1</td>

         *<tr align=right><td>1.0</td>  <td>1</td>

         *<tr align=right><td>-1.0</td> <td>-1</td>

         *<tr align=right><td>-1.1</td> <td>-1</td>

         *<tr align=right><td>-1.6</td> <td>-2</td>

         *<tr align=right><td>-2.5</td> <td>-2</td>

         *<tr align=right><td>-5.5</td> <td>-5</td>

         *</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>

         *<tr valign=top><th>Input Number</th>

         *    <th>Input rounded to one digit<br> with {@code HALF_EVEN} rounding

         *<tr align=right><td>5.5</td>  <td>6</td>

         *<tr align=right><td>2.5</td>  <td>2</td>

         *<tr align=right><td>1.6</td>  <td>2</td>

         *<tr align=right><td>1.1</td>  <td>1</td>

         *<tr align=right><td>1.0</td>  <td>1</td>

         *<tr align=right><td>-1.0</td> <td>-1</td>

         *<tr align=right><td>-1.1</td> <td>-1</td>

         *<tr align=right><td>-1.6</td> <td>-2</td>

         *<tr align=right><td>-2.5</td> <td>-2</td>

         *<tr align=right><td>-5.5</td> <td>-6</td>

         *</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>

         *<tr valign=top><th>Input Number</th>

         *    <th>Input rounded to one digit<br> with {@code UNNECESSARY} rounding

         *<tr align=right><td>5.5</td>  <td>throw {@code ArithmeticException}</td>

         *<tr align=right><td>2.5</td>  <td>throw {@code ArithmeticException}</td>

         *<tr align=right><td>1.6</td>  <td>throw {@code ArithmeticException}</td>

         *<tr align=right><td>1.1</td>  <td>throw {@code ArithmeticException}</td>

         *<tr align=right><td>1.0</td>  <td>1</td>

         *<tr align=right><td>-1.0</td> <td>-1</td>

         *<tr align=right><td>-1.1</td> <td>throw {@code ArithmeticException}</td>

         *<tr align=right><td>-1.6</td> <td>throw {@code ArithmeticException}</td>

         *<tr align=right><td>-2.5</td> <td>throw {@code ArithmeticException}</td>

         *<tr align=right><td>-5.5</td> <td>throw {@code ArithmeticException}</td>

         *</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");

        }

    }

}