Reusing scanner

[Pieter Jansens]

When using the scanner from system.in I can't reuse it. Say I want the user to give multiple input, do I really have to initialize a new scanner each time?
Example:

 Scanner scanner = new Scanner(System.in);
        int menuChoice = 0;
        while (menuChoice != 4) {
            System.out.println("""
                    ***Expo BookingService***
                    1. Plaats een bestelling
                    2. Vraag uw bestellingen op
                    3. Annuleer een bestelling
                    4. Stop
                    Druk het nr van uw corresponderende keuze.
                    """);
            menuChoice = scanner.nextInt();
            switch (menuChoice) {
                case 1 -> {
                    System.out.println("Geef uw naam op!");
                    String name = scanner.nextLine();
                    System.out.println("Geef het type van ticket (1 voor juniordag, 2 voor seniordag, 3 voor beide");
                    int type = scanner.nextInt();
                    service.create(new Bestellingen(0, name, type));
                }
                case 2 -> {
                    System.out.println("Geef uw naam op");
                    service.findByName(scanner.nextLine());
                }
                case 3 -> {
                    System.out.println("Geef de id van uw bestelling.");
                    Bestellingen bestelling = service.findById(scanner.nextLong());
                    if (bestelling != null) {
                        service.delete(bestelling);
                        System.out.println("De bestelling met id: " + bestelling.getId() + "werd succesvol geannulleerd");
                    }
                    else System.out.println("Deze bestelling werd niet gevonden");
                }
                case 4 -> {
                }
                default -> System.out.println("Wrong menuchoice");
            }
        }

Now when I press 1 to book a ticket that's the result:

***Expo BookingService***
1. Plaats een bestelling
2. Vraag uw bestellingen op
3. Annuleer een bestelling
4. Stop
Druk het nr van uw corresponderende keuze.

1
Geef uw naam op!
Geef het type van ticket (1 voor juniordag, 2 voor seniordag, 3 voor beide

As you can see the scanner takes the right menuchoice and executes the right switch case, but instead of waiting for the name of the users it asks for the type right away.
Is there a way to prevent that without initializing a new scanner?

[Piet Souris]

hi Pieter,

if you have:

var number = scanner.nextInt();

then if you type say 1, followed by an enter, then java reads that 1, but leaves a 'newline' in the scanners buffer. So the moment you do:

var name = scanner.nextLine();

then that pending newline is appointed to the variable 'name', and java goes on.

You can see this effect in lines 12-17.
A simple remedy is to put 'scanner.nextLine();' between lines 12 and 13, that will swallow that newline.

People here will show you some handy input-routines that will make life easy on you.

[Campbell Ritchie]

It is best to use a single Scanner object reading System.in for the whole application. The best way to do that is to crete a utility class reading inputs; if you search my posts for, “Scanner utility class,” you will eventually find such a utility class. I insist you acknowledge its source if you use it. It is better to understand the concepts behind it and write your own. I haven't managed to make such code thread‑safe.

But you won't find the whole class all in one place There is a serious mistake in one of my posts.