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/*
 * 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.
 *
 *<table class="striped">
 * <caption><b>Summary of Rounding Operations Under Different Rounding Modes</b></caption>
 * <thead>
 * <tr><th scope="col" rowspan="2">Input Number</th><th scope="col"colspan=8>Result of rounding input to one digit with the given
 * rounding mode</th>
 * <tr style="vertical-align:top">
 * <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>
 * </thead>
 * <tbody style="text-align:right">
 *
 * <tr><th scope="row">5.5</th> <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><th scope="row">2.5</th> <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><th scope="row">1.6</th> <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><th scope="row">1.1</th> <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><th scope="row">1.0</th> <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><th scope="row">-1.0</th> <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><th scope="row">-1.1</th> <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><th scope="row">-1.6</th> <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><th scope="row">-2.5</th> <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><th scope="row">-5.5</th> <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>
 * </tbody>
 * </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
 */
@SuppressWarnings("deprecation") // Legacy rounding mode constants in BigDecimal
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 class="striped">
 * <caption>Rounding mode UP Examples</caption>
 *<thead>
 *<tr style="vertical-align:top"><th scope="col">Input Number</th>
 * <th scope="col">Input rounded to one digit<br> with {@code UP} rounding
 *</thead>
 *<tbody style="text-align:right">
 *<tr><th scope="row">5.5</th> <td>6</td>
 *<tr><th scope="row">2.5</th> <td>3</td>
 *<tr><th scope="row">1.6</th> <td>2</td>
 *<tr><th scope="row">1.1</th> <td>2</td>
 *<tr><th scope="row">1.0</th> <td>1</td>
 *<tr><th scope="row">-1.0</th> <td>-1</td>
 *<tr><th scope="row">-1.1</th> <td>-2</td>
 *<tr><th scope="row">-1.6</th> <td>-2</td>
 *<tr><th scope="row">-2.5</th> <td>-3</td>
 *<tr><th scope="row">-5.5</th> <td>-6</td>
 *</tbody>
 *</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 class="striped">
 * <caption>Rounding mode DOWN Examples</caption>
 *<thead>
 *<tr style="vertical-align:top"><th scope="col">Input Number</th>
 * <th scope="col">Input rounded to one digit<br> with {@code DOWN} rounding
 *</thead>
 *<tbody style="text-align:right">
 *<tr><th scope="row">5.5</th> <td>5</td>
 *<tr><th scope="row">2.5</th> <td>2</td>
 *<tr><th scope="row">1.6</th> <td>1</td>
 *<tr><th scope="row">1.1</th> <td>1</td>
 *<tr><th scope="row">1.0</th> <td>1</td>
 *<tr><th scope="row">-1.0</th> <td>-1</td>
 *<tr><th scope="row">-1.1</th> <td>-1</td>
 *<tr><th scope="row">-1.6</th> <td>-1</td>
 *<tr><th scope="row">-2.5</th> <td>-2</td>
 *<tr><th scope="row">-5.5</th> <td>-5</td>
 *</tbody>
 *</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 class="striped">
 * <caption>Rounding mode CEILING Examples</caption>
 *<thead>
 *<tr style="vertical-align:top"><th>Input Number</th>
 * <th>Input rounded to one digit<br> with {@code CEILING} rounding
 *</thead>
 *<tbody style="text-align:right">
 *<tr><th scope="row">5.5</th> <td>6</td>
 *<tr><th scope="row">2.5</th> <td>3</td>
 *<tr><th scope="row">1.6</th> <td>2</td>
 *<tr><th scope="row">1.1</th> <td>2</td>
 *<tr><th scope="row">1.0</th> <td>1</td>
 *<tr><th scope="row">-1.0</th> <td>-1</td>
 *<tr><th scope="row">-1.1</th> <td>-1</td>
 *<tr><th scope="row">-1.6</th> <td>-1</td>
 *<tr><th scope="row">-2.5</th> <td>-2</td>
 *<tr><th scope="row">-5.5</th> <td>-5</td>
 *</tbody>
 *</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 class="striped">
 * <caption>Rounding mode FLOOR Examples</caption>
 *<thead>
 *<tr style="vertical-align:top"><th scope="col">Input Number</th>
 * <th scope="col">Input rounded to one digit<br> with {@code FLOOR} rounding
 *</thead>
 *<tbody style="text-align:right">
 *<tr><th scope="row">5.5</th> <td>5</td>
 *<tr><th scope="row">2.5</th> <td>2</td>
 *<tr><th scope="row">1.6</th> <td>1</td>
 *<tr><th scope="row">1.1</th> <td>1</td>
 *<tr><th scope="row">1.0</th> <td>1</td>
 *<tr><th scope="row">-1.0</th> <td>-1</td>
 *<tr><th scope="row">-1.1</th> <td>-2</td>
 *<tr><th scope="row">-1.6</th> <td>-2</td>
 *<tr><th scope="row">-2.5</th> <td>-3</td>
 *<tr><th scope="row">-5.5</th> <td>-6</td>
 *</tbody>
 *</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 &ge; 0.5; otherwise, behaves as for
 * {@code RoundingMode.DOWN}. Note that this is the rounding
 * mode commonly taught at school.
 *
 *<p>Example:
 *<table class="striped">
 * <caption>Rounding mode HALF_UP Examples</caption>
 *<thead>
 *<tr style="vertical-align:top"><th scope="col">Input Number</th>
 * <th scope="col">Input rounded to one digit<br> with {@code HALF_UP} rounding
 *</thead>
 *<tbody style="text-align:right">
 *<tr><th scope="row">5.5</th> <td>6</td>
 *<tr><th scope="row">2.5</th> <td>3</td>
 *<tr><th scope="row">1.6</th> <td>2</td>
 *<tr><th scope="row">1.1</th> <td>1</td>
 *<tr><th scope="row">1.0</th> <td>1</td>
 *<tr><th scope="row">-1.0</th> <td>-1</td>
 *<tr><th scope="row">-1.1</th> <td>-1</td>
 *<tr><th scope="row">-1.6</th> <td>-2</td>
 *<tr><th scope="row">-2.5</th> <td>-3</td>
 *<tr><th scope="row">-5.5</th> <td>-6</td>
 *</tbody>
 *</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 &gt; 0.5; otherwise, behaves as for
 * {@code RoundingMode.DOWN}.
 *
 *<p>Example:
 *<table class="striped">
 * <caption>Rounding mode HALF_DOWN Examples</caption>
 *<thead>
 *<tr style="vertical-align:top"><th scope="col">Input Number</th>
 * <th scope="col">Input rounded to one digit<br> with {@code HALF_DOWN} rounding
 *</thead>
 *<tbody style="text-align:right">
 *<tr><th scope="row">5.5</th> <td>5</td>
 *<tr><th scope="row">2.5</th> <td>2</td>
 *<tr><th scope="row">1.6</th> <td>2</td>
 *<tr><th scope="row">1.1</th> <td>1</td>
 *<tr><th scope="row">1.0</th> <td>1</td>
 *<tr><th scope="row">-1.0</th> <td>-1</td>
 *<tr><th scope="row">-1.1</th> <td>-1</td>
 *<tr><th scope="row">-1.6</th> <td>-2</td>
 *<tr><th scope="row">-2.5</th> <td>-2</td>
 *<tr><th scope="row">-5.5</th> <td>-5</td>
 *</tbody>
 *</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 class="striped">
 * <caption>Rounding mode HALF_EVEN Examples</caption>
 *<thead>
 *<tr style="vertical-align:top"><th scope="col">Input Number</th>
 * <th scope="col">Input rounded to one digit<br> with {@code HALF_EVEN} rounding
 *</thead>
 *<tbody style="text-align:right">
 *<tr><th scope="row">5.5</th> <td>6</td>
 *<tr><th scope="row">2.5</th> <td>2</td>
 *<tr><th scope="row">1.6</th> <td>2</td>
 *<tr><th scope="row">1.1</th> <td>1</td>
 *<tr><th scope="row">1.0</th> <td>1</td>
 *<tr><th scope="row">-1.0</th> <td>-1</td>
 *<tr><th scope="row">-1.1</th> <td>-1</td>
 *<tr><th scope="row">-1.6</th> <td>-2</td>
 *<tr><th scope="row">-2.5</th> <td>-2</td>
 *<tr><th scope="row">-5.5</th> <td>-6</td>
 *</tbody>
 *</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 class="striped">
 * <caption>Rounding mode UNNECESSARY Examples</caption>
 *<thead>
 *<tr style="vertical-align:top"><th scope="col">Input Number</th>
 * <th scope="col">Input rounded to one digit<br> with {@code UNNECESSARY} rounding
 *</thead>
 *<tbody style="text-align:right">
 *<tr><th scope="row">5.5</th> <td>throw {@code ArithmeticException}</td>
 *<tr><th scope="row">2.5</th> <td>throw {@code ArithmeticException}</td>
 *<tr><th scope="row">1.6</th> <td>throw {@code ArithmeticException}</td>
 *<tr><th scope="row">1.1</th> <td>throw {@code ArithmeticException}</td>
 *<tr><th scope="row">1.0</th> <td>1</td>
 *<tr><th scope="row">-1.0</th> <td>-1</td>
 *<tr><th scope="row">-1.1</th> <td>throw {@code ArithmeticException}</td>
 *<tr><th scope="row">-1.6</th> <td>throw {@code ArithmeticException}</td>
 *<tr><th scope="row">-2.5</th> <td>throw {@code ArithmeticException}</td>
 *<tr><th scope="row">-5.5</th> <td>throw {@code ArithmeticException}</td>
 *</tbody>
 *</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");
 }
 }
}