Factorial of a Number using Java GUI

Submitted by donbermoy on Friday, May 9, 2014 - 09:55.

In this tutorial, i will going to teach you how to create a program that computes factorial of a number. We all know that factorial is defined only for natural numbers and it means as the continued product of successive natural numbers from 1 to the number inputted. Now let's start this tutorial! 1. Open JCreator or NetBeans and make a java program with a file name of factorial.java. 2. Import javax.swing package. Hence we will use a GUI (Graphical User Interface) here like the inputting the number.

import javax.swing.*;

3. Initialize your variable in your Main, variable numInput as string and make it as an input and variable n, i, f as int. n variable will be used for parsing the numInput variable to be int, i for the loop, and variable f for the factorial of a number.

int n,i,f;    
String numInput;
numInput = JOptionPane.showInputDialog(null, "Enter a number:");
n = Integer.parseInt(numInput);

4. Make a for loop statement that the parameters have variable i will be equal to variable n, i is greater or equal than 1, and will decrement. Also, make f is equal to 1, so that we will have the formula of f=f*1 to get the factorial.

f =1;
for(i=n;i>=1;i--){              
f = f*i;
}

5. Lastly, display the output of the program using JOptionPane.showMessageDialog.

 JOptionPane.showMessageDialog(null, "Factorial value is: " +f);
}

Output: output

Solution: 1 x 2 x 3 x 4 x 5 = 120 Here's the full code of this tutorial:

import javax.swing.*;
 
public class factorial {
 
  
    public static void main(String[] args) {
    
    
        int n,i,f;    
        String numInput;
        numInput = JOptionPane.showInputDialog(null, "Enter a number:");
                n = Integer.parseInt(numInput);
        //... Computation
                                  
             f =1;
                for(i=n;i>=1;i--){              
                 f = f*i;
                }
        //... Output
        JOptionPane.showMessageDialog(null, "Factorial value is: " +f);
    }
 
}

Hope this helps! :) Best Regards, Engr. Lyndon R. Bermoy IT Instructor/System Developer/Android Developer/Freelance Programmer If you have some queries, feel free to contact the number or e-mail below. Mobile: 09488225971 Landline: 826-9296 E-mail:[email protected] Add and Follow me on Facebook: https://www.facebook.com/donzzsky Visit and like my page on Facebook at: https://www.facebook.com/BermzISware

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