Password & OTP Generator In Java

by | Feb 21, 2023 | Basic Coding, Coding, Java

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Introduction of the Project

Welcome to the Java coding tutorial on how to build a Password & OTP Generator In Java. In the digital age, security is of paramount importance. With countless online accounts and sensitive data at risk, it’s essential to use strong and unique passwords. But how can you generate a secure password that’s easy to remember? And what about two-factor authentication? The solution is simple: a password and OTP generator in Java.

With just a few lines of code, you can create a tool that generates complex passwords and one-time passwords for enhanced security. Let’s explore how you can implement this powerful tool and keep your online identity safe and secure!

To make this Java project more interesting, we will enhance the GUI using Swing along with the functionality to generate 6 digit OTPs and 8 characters long password randomly.


1. To develop a password generator function that can create strong, unique, and random passwords with a variety of characters, including uppercase and lowercase letters, numbers, and special characters.

2. To create an OTP generator function that generates a random and unique six-digit code that can be used as a second-factor authentication.

3. To integrate the password and OTP generator functions into a Java application, allowing users to generate passwords and OTPs with ease.

4. Implement a user-friendly interface for the application that allows users to customize the generated passwords and OTPs to their specific requirements.

5. Ensure that the generated passwords and OTPs are secure by following best practices, such as using secure random number generators, hashing algorithms, and encryption techniques.

6. Test the application to ensure it generates unique, strong, and secure passwords and OTPs consistently.


Here are some prerequisites for developing a Password & OTP Generator In Java.

1. Proficiency in Java programming language and familiarity with its syntax and data structures.

2. Understanding of the concepts of secure password and OTP generation, including best practices for password and OTP strength, uniqueness, and randomness.

3. Swing Module which is used to build the program’s graphical user interface (GUI). Java’s Swing framework has several components that give developers the freedom and flexibility to create eye-catching interfaces for Windows-based applications. The best thing about using Swing to create components like tables, scrollbars and buttons is that the framework is platform independent.

4. Familiarity with cryptographic concepts and techniques, such as hashing, encryption, and secure random number generation.

5. Knowledge of Java development environments, such as Eclipse, NetBeans, or IntelliJ IDEA.

6. Understanding of software development best practices, such as code organization, version control, and testing.

7. Familiarity with the concept of user interfaces and designing user-friendly interfaces for software applications.

8. Knowledge of software testing methodologies and experience with testing Java applications.

9. Awareness of security vulnerabilities and mitigation techniques, including those related to password and OTP generation.

10. Knowledge of any specific libraries or APIs needed for the development of the password and OTP generator in Java.

Source Code

public class Main {
public static void main(String[] args) {
new Pass();

import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Objects;
import java.util.Random;
public class Pass {
private JPanel pass;
private JButton PASSWORDButton;
private JButton OTPButton;
private JLabel password;
private JLabel otp;
JFrame passFrame = new JFrame();
public Pass(){
PASSWORDButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
StringBuilder a = new StringBuilder();
for(char c = 'A'; c <= 'Z'; ++c)
for(char c = 'a'; c <= 'z'; ++c)
Random r = new Random();
char[] pass = new char[8];
for(int i=0;i<8;i++){
pass[i] = a.charAt(r.nextInt(a.length()));
String finalPass = "";
for(int i=0;i<pass.length;i++){
OTPButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String numbers = "0123456789";
Random rndm = new Random();
char[] otp1 = new char[6];
for (int i = 0; i < 6; i++) {
otp1[i] = numbers.charAt(rndm.nextInt(numbers.length()));
String finalOTP = "";
for(int i=0;i<otp1.length;i++){

Explanation of the Code

We basically had two major tasks. One involves creating the GUI, and the other is retrieval of information from SQL database & updating according to user’s input.

Let us look at the GUI first:

1. We have used 2 Jlabels for password & OTP.

2. The user interface consists of 2 buttons, “Password” & “OTP” respectively.

Moving to generate random numbers & digits, we will apply the following:

1. We will take 2 strings which have 0-9 digits & A-Z characters, both small & in capital.

2. Then we use random method of math class to choose any character from those strings and gather in array.

3. Finally, we have put the result in the desired Jlabel & update the UI.


Main Interface

Points To Remember

We have successfully built a Password & OTP Generator in Java. This Java project helps to generate random 8 characters long, password & 6 digit OTP. It is a very efficient way to have a strong random password & can be used further in suggesting them at various platforms. Here are some important points to keep in mind when developing a “Password & OTP Generator In Java”:

  • Always generate strong and unique passwords and OTPs to ensure maximum security for users.
  • Follow best practices for password and OTP generation, such as using a combination of uppercase and lowercase letters, numbers, and special characters and avoiding predictable patterns or commonly used phrases.
  • Use cryptographic techniques to ensure that the generated passwords and OTPs are secure and not susceptible to attacks, such as brute force or dictionary attacks.
  • Make sure to include error handling and input validation to prevent unexpected inputs or exceptions that could compromise the security of the generated passwords and OTPs.
  • Provide user-friendly interfaces that allow users to customize the generated passwords and OTPs according to their requirements while still adhering to best practices.
  • Ensure that the password and OTP generator application is compatible with various operating systems and browsers and that it can handle multiple user requests simultaneously without performance issues.
  • Test the application thoroughly to identify and address any bugs, errors, or security vulnerabilities that could compromise the security of the generated passwords and OTPs.
  • Keep the application up to date with the latest security patches and software updates to prevent any potential security breaches.


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