Random class in Java

I'm making a reservation system using Java, and I want to create random ID numbers. (The code I'm going to show isn't all the code in my class, its just the stuff that's relevant.)

I have named a field randomGenerator, which is a Random object and declared it in my constructor:

public class ReservationSystem {
     private Random randomGenerator;

     public ReservationSystem() {
           randomGenerator = new Random();
     }

And then this is the method that I am having difficulty with:

     public void generateCustomerID(String id, int numbersInID) {
     //incNumber stands for incremented number
     int incNumber = 1;
     //create a new array of numbers as big as the user has defined
     int[] numbers = new int[numbersInID];
     while(numbersInID < (incNumber +1)) {
         //add a new number to the array between 0 and 10
         numbers[incNumber] = randomGenerator.nextInt(10);
         incNumber++;
     }
     System.out.print(id);
     for(int number: numbers)
         System.out.print(number);
 }

In my application I have given these values:

  public class Application { 
       public static void main(String[] args) {
               reserve.generateCustomerID("AB-", 3);
        }
  }

And I have been receiving the output AB-000.