Question:

You have been tasked with creating a random password generator program in Java. In order to accomplish this task, you decide to utilize the Random class in Java.

Write a method named generatePassword that takes in an integer length as a parameter and returns a randomly generated password as a string. The password should meet the following criteria:

• The password length must be equal to the length parameter.
• The password must contain a combination of uppercase letters, lowercase letters, and numbers.
• The password must have at least one uppercase letter, one lowercase letter, and one number.
• The password can have additional characters other than uppercase letters, lowercase letters, and numbers.

The method signature is:

public static String generatePassword(int length)

Answer:

import java.util.Random;

public class RandomPasswordGenerator {

    public static void main(String[] args) {
        int passwordLength = 10;
        String password = generatePassword(passwordLength);
        System.out.println("Generated password: " + password);
    }

    public static String generatePassword(int length) {
        Random random = new Random();
        StringBuilder password = new StringBuilder();

        // Generate at least one uppercase letter
        password.append((char) (random.nextInt(26) + 'A'));

        // Generate at least one lowercase letter
        password.append((char) (random.nextInt(26) + 'a'));

        // Generate at least one number
        password.append(random.nextInt(10));

        // Generate remaining characters
        for (int i = 0; i < length - 3; i++) {
            int randomType = random.nextInt(3);
            switch (randomType) {
                case 0:
                    password.append((char) (random.nextInt(26) + 'A')); // Uppercase letter
                    break;
                case 1:
                    password.append((char) (random.nextInt(26) + 'a')); // Lowercase letter
                    break;
                case 2:
                    password.append(random.nextInt(10)); // Number
                    break;
            }
        }

        // Shuffle the password
        for (int i = 0; i < length; i++) {
            int randomIndex = random.nextInt(length);
            char temp = password.charAt(randomIndex);
            password.setCharAt(randomIndex, password.charAt(i));
            password.setCharAt(i, temp);
        }

        return password.toString();
    }
}

Explanation:

The solution above demonstrates how to generate a random password with the given length, as specified by the length parameter. Here's a breakdown of the steps involved:

1. Import the Random class from the java.util package, as it provides the necessary methods for generating random numbers.
2. Define a generatePassword method that takes in an integer length as a parameter and returns a string.
3. Create an instance of the Random class using Random random = new Random();.
4. Create a StringBuilder object named password to store the generated password.
5. To meet the criteria of having at least one uppercase letter, one lowercase letter, and one number, we generate one random uppercase letter (password.append((char) (random.nextInt(26) + 'A'))), one random lowercase letter (password.append((char) (random.nextInt(26) + 'a'))), and one random number (password.append(random.nextInt(10))).
6. Next, for the remaining characters, we use a loop and randomly choose from three types: uppercase letters, lowercase letters, and numbers. The loop runs length - 3 times to account for the already generated characters (one uppercase letter, one lowercase letter, and one number).
7. Finally, we shuffle the password using another loop. For each index, we randomly select another index within the password and swap the characters, therefore effectively shuffling the password.
8. The generatePassword method returns the generated password as a string using password.toString().

In the main method, we demonstrate th