Yes, the system you are creating does not interact with these numbers (like, they are not taken from a table that keeps the customers data). You just have to accept them, assuming that any 8 digit number provided is valid, you know? For instance, this is how the GUI of my project works: there's a JTable that shows all records in the database. There's an area that shows some data of the record that is selected in the JTable. When you click on any record, its data is shown in this area, which also has a JTextField where you insert any 8 digit number (it can be 98767433 or 16510200 or even 41610001!
). Then, when you click on the "Book Room" button, a JOptionPane.showConfirmDialog is shown, with some data of the room being booked, the number of the customer booking the room, and a phrase "Please make sure this information is correct. This action cannot be undone" (before you have this other doubt, I'll tell you now
). An "unbook" function is not required in this project (that is, updating the customer ID field so it is blank again), that's why I did not implement one (and another advice: stick to simplicity). When you confirm the booking of the room, the record is updated with that customer ID. Do not forget to make sure that the client updating that record has locked it first. You also have to check this in your delete method (note the comments of the lock method in your interface).
If you have further questions, please let me know!