代号一个动作监听器不起作用

Question

I'm currently working on building my first app. :) I've now coded several Forms, each in an own class. Now, I want to implement the navigation from one Form to another, this is pretty straight forward since there is always only one "next" Form for every Form currently.

So i tried to do this by adding a "nextForm" Form to every Class and I want nextForm.show() every time the "next" Button is pressed. I tried it this way:

login = new Button("Login");
    login.setUIID("nxtButtons");
    login.addActionListener((e) ->
            nextForm.show()
    );

So, when i actually click the button, nothing happens.

Is the way I try to code this a good way? This is the first time Im heading into GUI building and I don't have experience here yet. Maybe one of you guys could help me here :)

Thank you very much

Kind regards,

Max

Answer 1

I'm assuming nextForm is null and you should see the null pointer exception in the console somewhere.

If not nextForm might be pointing at the current form which will do nothing. You can place a break point on that line in the debugger and see that the break point is reached then inspect the values of the variables.