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How to format a number?

If you want to display some numbers that is formatted to a certain pattern, either in a Java Swing application or in a JSP file, you can utilize NumberFormat and DecimalFormat class to give you the format that you want. Here is a small example that will show you how to do it.

package com.javacoderanch.example.text;

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));
    }
}

Here is the different result of the code above.

1.0055000075E8
100550000.75