RoundingMode.java

/*
 * Copyright 2009 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with this
 * work for additional information regarding copyright ownership. The ASF
 * licenses this file to You under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 * 
 * INCLUDES MODIFICATIONS BY RICHARD ZSCHECH AS WELL AS GOOGLE.
 */
package java.math;

/**
 * Specifies the rounding behavior for operations whose results cannot be
 * represented exactly.
 */
public enum RoundingMode {

  /**
   * Rounding mode where positive values are rounded towards positive infinity
   * and negative values towards negative infinity. <br>
   * Rule: {@code x.round().abs() >= x.abs()}
   */
  UP,

  /**
   * Rounding mode where the values are rounded towards zero. <br>
   * Rule: {@code x.round().abs() <= x.abs()}
   */
  DOWN,

  /**
   * Rounding mode to round towards positive infinity. For positive values this
   * rounding mode behaves as {@link #UP}, for negative values as {@link #DOWN}. <br>
   * Rule: {@code x.round() >= x}
   */
  CEILING,

  /**
   * Rounding mode to round towards negative infinity. For positive values this
   * rounding mode behaves as {@link #DOWN}, for negative values as {@link #UP}. <br>
   * Rule: {@code x.round() <= x}
   */
  FLOOR,

  /**
   * Rounding mode where values are rounded towards the nearest neighbor. Ties
   * are broken by rounding up.
   */
  HALF_UP,

  /**
   * Rounding mode where values are rounded towards the nearest neighbor. Ties
   * are broken by rounding down.
   */
  HALF_DOWN,

  /**
   * Rounding mode where values are rounded towards the nearest neighbor. Ties
   * are broken by rounding to the even neighbor.
   */
  HALF_EVEN,

  /**
   * Rounding mode where the rounding operations throws an ArithmeticException
   * for the case that rounding is necessary, i.e. for the case that the value
   * cannot be represented exactly.
   */
  UNNECESSARY;
  
  /**
   * Converts rounding mode constants from class {@code BigDecimal} into {@code
   * RoundingMode} values.
   * 
   * @param mode rounding mode constant as defined in class {@code BigDecimal}
   * @return corresponding rounding mode object
   */
  public static RoundingMode valueOf(int mode) {
    switch (mode) {
      case BigDecimal.ROUND_CEILING:
        return CEILING;
      case BigDecimal.ROUND_DOWN:
        return DOWN;
      case BigDecimal.ROUND_FLOOR:
        return FLOOR;
      case BigDecimal.ROUND_HALF_DOWN:
        return HALF_DOWN;
      case BigDecimal.ROUND_HALF_EVEN:
        return HALF_EVEN;
      case BigDecimal.ROUND_HALF_UP:
        return HALF_UP;
      case BigDecimal.ROUND_UNNECESSARY:
        return UNNECESSARY;
      case BigDecimal.ROUND_UP:
        return UP;
      default:
        // math.00=Invalid rounding mode
        throw new IllegalArgumentException("Invalid rounding mode");
    }
  }
}