Question:

Explain the use of the Random class in Java and demonstrate its implementation by creating a program that generates a random password with the following criteria:

• The password should have a length of 8 characters.
• It should contain a combination of uppercase letters, lowercase letters, and digits.

Provide the code for the program and explain the role of the Random class in generating the password.

Answer:

The Random class in Java is used to generate random numbers or values. It is often used in applications such as gaming, simulations, and security where randomization is required.

Below is a program implementing the Random class to generate a random password with the specified criteria:

import java.util.Random;

public class RandomPasswordGenerator {
    public static void main(String[] args) {
        String password = generateRandomPassword();
        System.out.println("Random Password: " + password);
    }

    public static String generateRandomPassword() {
        String uppercaseLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String lowercaseLetters = "abcdefghijklmnopqrstuvwxyz";
        String digits = "0123456789";

        String validChars = uppercaseLetters + lowercaseLetters + digits;
        
        Random random = new Random();
        StringBuilder password = new StringBuilder(8);
        
        for (int i = 0; i < 8; i++) {
            int index = random.nextInt(validChars.length());
            password.append(validChars.charAt(index));
        }
        
        return password.toString();
    }
}

Explanation:

In the program, we first define the valid characters to be used in the password, which include uppercase letters, lowercase letters, and digits. We then create a Random object to generate random numbers.

Inside the method generateRandomPassword(), we use a for loop to iterate 8 times to generate each character of the password. For each iteration, we use the nextInt() method of Random to get a random index within the length of the valid characters string, and then fetch the character at that index and append it to the password. Finally, the generated password is returned as a string.

This program demonstrates how the Random class can be used to create a random password that meets specific criteria.