如何从控制器JavaFx中分离逻辑

Question

我遇到了从控制器中分离业务逻辑的问题（除了我在程序中验证数据的方式）。

这是逻辑类：

public class LogInMechanism {

LogInController logInController = new LogInController();
private static int howManyAttempts=0;

public void logIn()
{
howManyAttempts++;
if(howManyAttempts <3)
{
    if(logInController.getLogInField().getText().equals("nick") && logInController.getPasswordField().getText().equals("password"))
    {
        System.out.println("Button clicked");
        try {
            Parent root = FXMLLoader.load(getClass().getResource("/fxml/MainWindow.fxml"));
            logInController.getLogInField().getScene().setRoot(root);
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
    else
    {
        logInController.getInvalidUserOrPasswordLabel().setText("Invalid user or password "+(3-howManyAttempts)+ " attempts left!");
        logInController.getInvalidUserOrPasswordLabel().setVisible(true);
    }
}
else
{

    logInController.getInvalidUserOrPasswordLabel().setDisable(true);
    logInController.getInvalidUserOrPasswordLabel().setText("Your program has been blocked. Please contact manager!");


}
}


}

我希望在我的一个控制器中使用此功能

public class LogInController {
private LogInMechanism logInMechanism = new LogInMechanism();

@FXML
private Label invalidUserOrPasswordLabel;

@FXML
private TextField logInField;

@FXML
private Button logInButton;

@FXML
private PasswordField passwordField;

@FXML
void logInButtonClicked(ActionEvent event) {
    logInMechanism.logIn();
}

@FXML
public void initialize()
{
    EventHandler<KeyEvent> handlerLambda = e ->{
        if(e.getCode()==KeyCode.ENTER)
        {
        //  logInMechanism.logIn();
        }

    };
    logInButton.addEventHandler(KeyEvent.KEY_PRESSED, handlerLambda);
}

public Label getInvalidUserOrPasswordLabel() {
    return invalidUserOrPasswordLabel;
}

public TextField getLogInField() {
    return logInField;
}

public PasswordField getPasswordField() {
    return passwordField;
}

但不幸的是ifter执行这样的代码我收到了一个错误：

Exception in Application start method
java.lang.reflect.InvocationTargetException
Caused by: java.lang.RuntimeException: Exception in Application start method
Caused by: java.lang.StackOverflowError

错误出现在LogInMechanism类的第19行。我还在学习，如果你有什么建议请分享。