Show a reasonable number of significant digits. - Java java.lang

Java examples for java.lang:int Binary

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Description

Show a reasonable number of significant digits.

Demo Code

/** Copyright by Barry G. Becker, 2000-2011. Licensed under MIT License: http://www.opensource.org/licenses/MIT  */
//package com.java2s;
import java.text.DecimalFormat;

public class Main {
    private static final DecimalFormat expFormat_ = new DecimalFormat(
            "0.###E0");
    private static final DecimalFormat format_ = new DecimalFormat(
            "###,###.##");
    private static final DecimalFormat intFormat_ = new DecimalFormat(
            "#,###");

    /**/*from ww  w . j  a  v  a 2s  .  c o  m*/
     * Show a reasonable number of significant digits.
     * @param num the number to format.
     * @return a nicely formatted string representation of the number.
     */
    public static String formatNumber(double num) {
        double absnum = Math.abs(num);

        if (absnum == 0) {
            return "0";
        }
        if (absnum > 10000000.0 || absnum < 0.000000001) {
            return expFormat_.format(num);
        }

        if (absnum > 1000.0) {
            format_.setMinimumFractionDigits(0);
            format_.setMaximumFractionDigits(0);
        } else if (absnum > 100.0) {
            format_.setMinimumFractionDigits(1);
            format_.setMaximumFractionDigits(1);
        } else if (absnum > 1.0) {
            format_.setMinimumFractionDigits(1);
            format_.setMaximumFractionDigits(3);
        } else if (absnum > 0.0001) {
            format_.setMinimumFractionDigits(2);
            format_.setMaximumFractionDigits(5);
        } else if (absnum > 0.000001) {
            format_.setMinimumFractionDigits(3);
            format_.setMaximumFractionDigits(8);
        } else {
            format_.setMinimumFractionDigits(6);
            format_.setMaximumFractionDigits(11);
        }

        return format_.format(num);
    }

    /**
     * @param num the number to format.
     * @return a nicely formatted string representation of the number.
     */
    public static String formatNumber(long num) {
        return intFormat_.format(num);
    }

    /**
     * @param num the number to format.
     * @return a nicely formatted string representation of the number.
     */
    public static String formatNumber(int num) {
        return intFormat_.format(num);
    }
}

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