Round the given value to the specified number of decimal places. The value is rounded using the BigDecimal.ROUND_HALF_UP method. : Math Functions « Development « Java Tutorial

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import java.math.BigDecimal;

/* 
 * 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.
 *
 *
 */
public class Main {
  /**
   * Round the given value to the specified number of decimal places. The
   * value is rounded using the {@link BigDecimal#ROUND_HALF_UP} method.
   * 
   * @param x the value to round.
   * @param scale the number of digits to the right of the decimal point.
   * @return the rounded value.
   * @since 1.1
   */
  public static double round(double x, int scale) {
      return round(x, scale, BigDecimal.ROUND_HALF_UP);
  }

  /**
   * Round the given value to the specified number of decimal places. The
   * value is rounded using the given method which is any method defined in
   * {@link BigDecimal}.
   * 
   * @param x the value to round.
   * @param scale the number of digits to the right of the decimal point.
   * @param roundingMethod the rounding method as defined in
   *        {@link BigDecimal}.
   * @return the rounded value.
   * @since 1.1
   */
  public static double round(double x, int scale, int roundingMethod) {
      try {
          return (new BigDecimal
                 (Double.toString(x))
                 .setScale(scale, roundingMethod))
                 .doubleValue();
      } catch (NumberFormatException ex) {
          if (Double.isInfinite(x)) {
              return x;          
          } else {
              return Double.NaN;
          }
      }
  }

}