Random username generator with random number behind errors

Question

I have been on this for about an hour and I really can't figure this out, I am suppose to make something that prompts for and reads the user's first and last name (separately). Then print a string composed of the first letter of the user's first name, followed by the first five characters of the user's last name, followed by a random number in the range 10 to 99. and assume that the last name is at least five letters long

import java.util.Scanner;  //Needed for the Scanner class  
import java.lang.String;

import java.util.Random;

public class UsernameGenerator
{    
public static void main(String[] args)  //all the action happens here!    
{  Scanner input = new Scanner (System.in);
    Random generator = new Random();

    int num1;
    num1 = generator.nextInt(10-99);

    String firstName;
    String lastName;
    String concatenatedName;

    System.out.println("Enter your First Name: ");
    firstName = input.next();



    System.out.print( "Enter your Last Name: " );
    lastName = input.next();


    // We'll take the first character in the first name
    concatenatedName = firstName.charAt(0) + lastName.substring(0, 5) + num1;



    Random rnd = new Random(); // Initialize number generator
    if (lastName.length() > 5)
        concatenatedName += lastName.substring(0,5);
    else
        concatenatedName += lastName; // You did not specify what to do, if the name is shorter than 5 chars

    concatenatedName += Integer.toString(rnd.nextInt(99));


    System.out.println();

}
}

Answer 1

You should try something like this to deal with the fact the lastname might not be 5 characters in length. The latter part of your function - where you set check the length and add another random number is not required.

    // We'll take the first character in the first name
    try
    {
        concatenatedName = firstName.charAt(0) + lastName.substring(0, 5) + num1;
    }
    catch (Exception e)
    {
        // Here we deal with the fact we might not be able to get 5 characters from the last name
        // - Just add the full lastname
        concatenatedName = firstName.charAt(0) + lastName + num1;
    }

    System.out.println(concatenatedName);

Answer 2

This will print what wanted at the end of your code, not a bad start, keep up the hard work

can anyone figure out this part? I am practicing (:

Then, if you like, enhance it so that if the last name is less than 5 characters long, it inserts extra random characters or digits so that the generated user name still contains 8 characters. This is an optional enhancement.

Random rnd = new Random(); // Initialize number generator
if (lastName.length() > 5)
    concatenatedName += lastName.substring(0,5);
else
    concatenatedName += lastName; // You did not specify what to do, if the name is shorter than 5 chars

concatenatedName += Integer.toString(rnd.nextInt(99));
System.out.println(concatenatedName);