Can I use a do-while loop with Vaadin? If I do the localhost:8080 shows a loading bar that almost fills but never does

A project for school requires us to make a Web Application for various conversions. For the time being I am using localhost:8080 to test as I build. The instructions require a do-while loop for the initial menu. I have the logic up to the first temperature conversion (F to C) and it works just fine until I add a do-while.

So far I've tried wrapping the entire code in the do-while and just the menu in a do-while (I haven't tried every single possibility of do-while placement yet). In both cases the page shows a loading bar that almost fills, starts flashing, and stays there, forever loading. Surely I'm missing something simple?

        add(new H1("Welcome to the Conversion Challenge!"));

        IntegerField menuChoice = new IntegerField();
        Button chooseConversionButton = new Button("Onward!");
        AtomicInteger inputValue = new AtomicInteger(-1);
        do
        {
            add(new H3("What method of conversion would you like to indulge in?"));
            add(new Paragraph("1) A temperate one?"));
            add(new Paragraph("2) Something heavier?"));
            add(new Paragraph("3) Maybe you're money-minded?"));
            add(new Paragraph("4) Or just give up!"));

            menuChoice.setLabel("What is your choice?");
            menuChoice.setHelperText("Don't be silly... go ahead.");
            add(menuChoice, chooseConversionButton);

        
            chooseConversionButton.addClickListener(eventChooseConversion -> {
                inputValue.set(menuChoice.getValue());

                removeAll();

                switch(inputValue.get())
                { 
        ... code continues 
       } while(inputValue.intValue() != 4);

I think you have misunderstood the concept of Vaadin. You Java code runs on the server and the UI is shown on the Browser. This means that there is two machines and a network connection between them. I.e. it is a distributed system. Thus in Vaadin application, everything is based on events and event handling.

chooseConversionButton.addClickListener(eventChooseConversion -> { .. };

The execution is not stopping here waiting for input. The main thread execution continues. Instead the callback in the listener is executed when the event happens. The blocking actions are not possible in any distributed system such as Vaadin.

Thus in your code do - while loop is practically eternal loop. Based on your comment it is completely un-necessary here.

So if you want to present a menu and take input, and have "something" that needs to be done when input is taken, you need to call that "something" in the event handler.

I recommend to browse thru the Tutorial section of the Vaadin documentation and download app starter to play with the concept.