How to Generate a Random 17-Character Alpha-Numeric String in Java?

How can I generate a random 17-character alphanumeric string (containing A-Z and 0-9) in Java?

// Code to generate a random alphanumeric string in Java
public static String generateRandomString(int length) {
    String characters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    StringBuilder result = new StringBuilder();
    Random random = new Random();

    for (int i = 0; i < length; i++) {
        int index = random.nextInt(characters.length());
        result.append(characters.charAt(index));
    }
    return result.toString();
}

public static void main(String[] args) {
    String randomString = generateRandomString(17);
    System.out.println(randomString);
}

To generate a random 17-character alphanumeric string in Java, you can use the Random class along with a specific character set consisting of uppercase letters and digits. This method eliminates the need for complex logic by using simple concatenation and character selection from a predefined string.

// Complete code to generate a random 17-character alphanumeric string in Java
import java.util.Random;

public class RandomStringGenerator {
    public static String generateRandomString(int length) {
        String characters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        StringBuilder result = new StringBuilder();
        Random random = new Random();

        for (int i = 0; i < length; i++) {
            int index = random.nextInt(characters.length());
            result.append(characters.charAt(index));
        }
        return result.toString();
    }

    public static void main(String[] args) {
        String randomString = generateRandomString(17);
        System.out.println(randomString);
    }
}

Solutions

• Utilize the Random class in Java to simplify the process of generating random characters.
• Create a method that builds a string using a loop to append random characters from a defined character set.
• Use StringBuilder for efficient string concatenation instead of using the '+' operator.

Mistake: Using `Math.random()` instead of `Random` class for character selection.

Solution: The `Random` class is more suitable for generating random indices in a controlled manner.

Mistake: Not checking if the generated string meets the required length.

Solution: Ensure the loop runs exactly the number of times specified as the length parameter.

Mistake: Overcomplicating the selection logic (using multiple arrays).

Solution: Keep it simple by using a single string that contains all valid characters.