Java: Specifying how many numbers after the decimal point

Question

I have a GUI Java code for calculating the range of data for example if two values entered 2.444 and 3.555 the result will be a long double 1.11100000... etc. How do I specify how many digits after the decimal point it should display? (ex: %.2f)

This is my code:

public class Range
{
    public static void main(String args[])
    {
        int num=0; //number of data
        double d; //the data
        double smallest = Integer.MAX_VALUE;
        double largest = Integer.MIN_VALUE;
        double range = 0;

        String Num =
        JOptionPane.showInputDialog("Enter the number of data ");
        num=Integer.parseInt(Num);

        for(int i=0; i<num; i++)    
        {
            String D =
            JOptionPane.showInputDialog("Enter the data ");
            d=Double.parseDouble(D);

            if(d < smallest)
                smallest = d;
            if(d > largest)
                largest = d; 
        }

        range = largest - smallest ; //calculating the range of the input

        JOptionPane.showMessageDialog(null,"Range = "+smallest+"-"+largest+" = "+range,"Range",JOptionPane.PLAIN_MESSAGE);
    }
}

score 8 · Accepted Answer · answered Dec 26 '11 at 18:54

8

You can use String.format to define the output you like, e.g.

String.format("Range = %.4f", range)

to show 4 decimal places.

answered Dec 26 '11 at 18:54

Howard

38,639
9
64
83

is this statement will display the result in gui? – Aisha S Dec 27 '11 at 16:31
This method returns a string representation so you can replace the code inside `showMessageDialog`. – Howard Dec 27 '11 at 16:34

score 3 · Answer 2 · answered Dec 26 '11 at 18:54

DecimalFormat. Below example form here

import java.text.DecimalFormat;
import java.text.NumberFormat;

public class DecimalFormatExample
{
    public static void main(String[] args)
    {
        // We have some millons money here that we'll format its look.
        double money = 100550000.75;

        // By default to toString() method of the Double data type will print
        // the money value using a scientific number format as it is greater
        // than 10^7 (10,000,000.00). To be able to display the number without
        // scientific number format we can use java.text.DecimalFormat wich
        // is a sub class of java.text.NumberFormat.

        // Below we create a formatter with a pattern of #0.00. The # symbol
        // means any number but leading zero will not be displayed. The 0 
        // symbol will display the remaining digit and will display as zero
        // if no digit is available.
        NumberFormat formatter = new DecimalFormat("#0.00");

        // Print the number using scientific number format.
        System.out.println(money);

        // Print the number using our defined decimal format pattern as above.
        System.out.println(formatter.format(money));
    }
}

score 1 · Answer 3 · answered Apr 25 '19 at 23:58

1

Use this:

double x = new Random.nextDouble(); //ex: x = 0.126521478419346598
x = Math.round(x*1000)/1000.0;  //x will be: 0.126

answered Apr 25 '19 at 23:58

Younes Meridji

149
5

score -1 · Answer 4 · answered Jul 25 '13 at 15:05

add this instance of DecimalFormat to the top of your method:

DecimalFormat three = new DecimalFormat("0.000");

// or this. this will modify the number to have commas every new thousandths place.
DecimalFormat three = new DecimalFormat("#,##0.000");

// the three zeros after the decimal point above specify how many decimal places to be accurate to.
// the zero to the left of the decimal place above makes it so that numbers that start with "0." will display "0." vs just "." If you don't want the "0.", replace that 0 to the left of the decimal point with "#"

then, call this instance and pass it a string when displaying:

String str = 4.651681351;
display.setText(three.format(str)); // displays 4.652

Java: Specifying how many numbers after the decimal point

4 Answers4