JavaFX button reacting on second click not first

Question

I am trying to create my very first application in JavaFX and I have a problem with Button that calls a method (for example to open another window) - I always have to click

Answer 1

Most likely you have the following in your FXML:

<Button fx:id="forgot" onAction="#forgetPasswordClicked" />

This makes your button forgot call your method forgetPasswordClicked(). But instead of defining your logic to be executed when your button is clicked, the first time you say: "When this button is clicked, place an action event on my button which will call setUpWindow()"

forgot.setOnAction(e -> ForgotPassword.setUpWindow());

Therefore, your first click "sets up" the logic of your button. The second click, actually executes it. To solve this, either immediately use your logic as such:

public void forgetPasswordClicked() {
    ForgotPassword.setUpWindow();
}

or don't define the method to be called in your fxml, and move the initialization of your button (setting the action listener) to your initialization as following:

public class ControllerSignIn implements Initializable {
    @FXML
    private Button forgot;
    @FXML
    private Button back;

    @Override
    public void initialize(URL location, ResourceBundle resources) {
        forgot.setOnAction(e -> ForgotPassword.setUpWindow());
        back.setOnAction(e -> ForgotPassword.closeWindow());
    }
}

This is also why your signInClicked() method works from the first click, because it actually executes the logic instead of setting up the handler first.