Getter returning correctly, then changes to null

Question

So I'm having an unusual issue where code is detecting the current user with the method getCurrentUser() but when I use it later to check which user borrowed a book it returns null.

I also attempted changing line 3 of borrowBook method to the currentUser variable, and also tried getting the info through usernameTxtField.getText()

public class Controller {
private Book HFJ = new Book("HFJ", "SI & BA","5678",3, 1);

@FXML
private void attemptLogin(ActionEvent event) throws IOException {
    String usernameInput = usernameTxtField.getText();
    String passwordInput = passwordTxtField.getText();
    boolean loginSuccessful = false;


    switch (usernameInput.toLowerCase()) {
        case "user1":
            if (passwordInput.equals("Password1")) {
                System.out.println("Login Successful");
                informationLabel.setText("Login Successful");
                loginSuccessful = true;
                currentUser = usernameInput.toLowerCase();
            }
            break;
        case "user2":
            if (passwordInput.equals("Password2")) {
                System.out.println("Login Successful");
                informationLabel.setText("Login Successful");
                loginSuccessful = true;
                currentUser = usernameInput.toLowerCase();
            }
            break;
        case "user3":
            if (passwordInput.equals("Password3")) {
                System.out.println("Login Successful");
                informationLabel.setText("Login Successful");
                loginSuccessful = true;
                currentUser = usernameInput.toLowerCase();
            }
            break;
        case "user4":
            if (passwordInput.equals("Password4")) {
                System.out.println("Login Successful");
                informationLabel.setText("Login Successful");
                loginSuccessful = true;
                currentUser = usernameInput.toLowerCase();
            }
            break;
        default:
            System.out.println("Incorrect username or Password");
            informationLabel.setText("Incorrect username or Password");
            break;
    }

    if (loginSuccessful == true) {
        Parent home = FXMLLoader.load(getClass().getResource("home.fxml"));
        Scene home_scene = new Scene(home);
        Stage primaryStage = (Stage) ((Node) event.getSource()).getScene().getWindow();
        primaryStage.setScene(home_scene);
        primaryStage.show();
        currentUser = usernameInput.toLowerCase();
        System.out.println(getCurrentUser());
        homeLoginInfoLabel.setText("Login Successful");
    }
}
@FXML private Label HFJQuantity = new Label();
@FXML private Button HFJBorrowBtn = new Button();
@FXML
private void borrowBook(ActionEvent event) throws IOException{
    if(HFJ.getQuantity()>=1){
        HFJ.setQuantity(HFJ.getQuantity() -1);
        System.out.println("Book Borrowed By: " + getCurrentUser());//CONSOLE PRINT
        HFJQuantity.setText("" + HFJ.getQuantity());
        Parent borrowSuccessful = FXMLLoader.load(getClass().getResource("borrowSuccess.fxml"));
        Scene success_scene = new Scene(borrowSuccessful);
        Stage primaryStage = (Stage) ((Node) event.getSource()).getScene().getWindow();
        primaryStage.setScene(success_scene);
        primaryStage.show();
    }else{
        System.out.println("Not enough books");
        HFJBorrowBtn.setDisable(true);
    }

}


private String getCurrentUser() {
    return currentUser;
}

When I run the code and login this is what the console prints:

Login Successful
user1
Book Borrowed By: null

Why isn't it recognising the current user? Any help would be great

Answer 1

I think the problem you are having is down to scope. I can't see in this class where you have declared currentUser outside of the switch statement or the if/else. Try initialising currentUser at the top with your other class variable.