Java Double Number Round round(final double val, final int decimals)

Description

Rounds the given double value to a certain number of decimal places.

License

Open Source License

Parameter

Parameter	Description
val	The value to round.
decimals	The number of decimals to round to.

Return

The rounded values.

Declaration

public static double round(final double val, final int decimals) 

Method Source Code

//package com.java2s;
/*******************************************************************************
 * This file is part of jasima, v1.3, the Java simulator for manufacturing and 
 * logistics.//from w  w w .j  ava2  s .co  m
 *  
 * Copyright (c) 2015       jasima solutions UG
 * Copyright (c) 2010-2015 Torsten Hildebrandt and jasima contributors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *******************************************************************************/

public class Main {
    /**
     * Rounds the given double value to a certain number of decimal places.
     * {@code decimals} can be positive or negative.
     * 
     * @see #round(double[], int)
     * @param val
     *            The value to round.
     * @param decimals
     *            The number of decimals to round to.
     * @return The rounded values.
     */
    public static double round(final double val, final int decimals) {
        if (decimals >= 0) {
            long fact = powerOfTen(decimals);
            return Math.round(val * fact) / ((double) fact);
        } else {
            long fact = powerOfTen(-decimals);
            return Math.round(val / fact) * ((double) fact);
        }
    }

    /**
     * Rounds all values in the double array {@code vs} to a certain number of
     * decimal places. This method does not create a copy of {@code vs}, but
     * modifies its contents.
     * 
     * @return the parameter {@code vs} to allow easy chaining of method calls.
     * 
     * @see #round(double, int)
     * @param vs
     *            An array of doubles to round.
     * @param decimals
     *            The number of decimals to round the values.
     * @return An array with rounded values.
     */
    public static double[] round(final double[] vs, final int decimals) {
        for (int i = 0; i < vs.length; i++) {
            vs[i] = round(vs[i], decimals);
        }
        return vs;
    }

    private static long powerOfTen(int exp) {
        assert exp >= 0;

        long fact = 1;
        for (int i = 0; i < exp; i++) {
            fact *= 10;
        }
        return fact;
    }
}

Related

1. round(final double num)
2. round(final double num, final int prec)
3. round(final double numberToRound, final int decimalPlaces)
4. round(final double v)
5. round(final double val, final int decimalPlaces)
6. round(final Double value)
7. round(final Double value)
8. round(final double value, final int numDecimals)
9. round(final double x, final int digits)