Generating Password and OTP in Java

You may go through Generate a One Time Password or Unique Identification URL article before this for better understanding.

Generating Password and OTP in Java
Many a times we forget our passwords and we opt for Forget password option and within no time we get a new password at our registered email-ID or phone no. to login our account. And every time we get a different password.
Sometime we access our bank accounts while shopping from an online store or many more ways, in order to verify our transition from the bank account they send us OTP(One Time Password) on our registered phone no. or our email-ID, within no time.

The following code explains how to generate such Passwords and OTP within no time and what code we can use if in case we need to do so.

Java program explaining the generation of Password

// Java code to explain how to generate random
// password

// Here we are using random() method of util
// class in Java
import java.util.*;

public class NewClass
{
    public static void main(String[] args)
    {
        // Length of your password as I have choose
        // here to be 8
        int length = 10;
        System.out.println(geek_Password(length));
    }

    // This our Password generating method
    // We have use static here, so that we not to
    // make any object for it
    static char[] geek_Password(int len)
    {
        System.out.println("Generating password using random() : ");
        System.out.print("Your new password is : ");

        // A strong password has Cap_chars, Lower_chars,
        // numeric value and symbols. So we are using all of
        // them to generate our password
        String Capital_chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String Small_chars = "abcdefghijklmnopqrstuvwxyz";
        String numbers = "0123456789";
                String symbols = "!@#$%^&*_=+-/.?<>)";


        String values = Capital_chars + Small_chars +
                        numbers + symbols;

        // Using random method
        Random rndm_method = new Random();

        char[] password = new char[len];

        for (int i = 0; i < len; i++)
        {
            // Use of charAt() method : to get character value
            // Use of nextInt() as it is scanning the value as int
            password[i] =
              values.charAt(rndm_method.nextInt(values.length()));

        }
        return password;
    }
}

Note : The password we are generating will change every time. As we have used random() method to generate the password.
Output :

Generating password using random() : 
Your new password is : KHeCZBTM;-

Java program explaining the generation of OTP(One Time Password)

// Java code to explain how to generate OTP

// Here we are using random() method of util
// class in Java
import java.util.*;

public class NewClass
{
    static char[] OTP(int len)
    {
        System.out.println("Generating OTP using random() : ");
        System.out.print("You OTP is : ");

        // Using numeric values
        String numbers = "0123456789";

        // Using random method
        Random rndm_method = new Random();

        char[] otp = new char[len];

        for (int i = 0; i < len; i++)
        {
            // Use of charAt() method : to get character value
            // Use of nextInt() as it is scanning the value as int
            otp[i] =
             numbers.charAt(rndm_method.nextInt(numbers.length()));
        }
        return otp;
    }
    public static void main(String[] args)
    {
        int length = 4;
        System.out.println(OTP(length));
    }
}

Note :
The OTP we are generating will change every time. As we have used random() method to generate the OTP.
Output :

Generating OTP using random() : 
You OTP is : 5291

This article is contributed by Mohit Gupta 🙂. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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