Implementation of generating website invitation codes in JAVA.

Here is a simple example code in JAVA for generating website invitation codes.

import java.util.Random;

public class InvitationCodeGenerator {

    private static final String CHARACTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    private static final int CODE_LENGTH = 8;

    public static String generateInvitationCode() {
        StringBuilder codeBuilder = new StringBuilder();

        Random random = new Random();
        for (int i = 0; i < CODE_LENGTH; i++) {
            int randomIndex = random.nextInt(CHARACTERS.length());
            char randomChar = CHARACTERS.charAt(randomIndex);
            codeBuilder.append(randomChar);
        }

        return codeBuilder.toString();
    }

    public static void main(String[] args) {
        String invitationCode = generateInvitationCode();
        System.out.println("Generated Invitation Code: " + invitationCode);
    }
}

This sample code utilizes a character set containing uppercase letters and numbers, with a length of 8 characters. The code uses a random number generator to select random characters from the character set, and then combines these characters into an invitation code. Running the main method will output the generated invitation code.