package de.kneitzel; import javafx.event.ActionEvent; import javafx.fxml.FXML; import javafx.fxml.Initializable; import javafx.scene.control.Button; import javafx.scene.control.TextField; import java.net.URL; import java.util.ResourceBundle; public class MainWindow implements Initializable { @FXML private TextField textField; public Button button; @Override public void initialize(URL url, ResourceBundle resourceBundle) { if (button == null) { textField.setText("Button is null"); } else { textField.setText("Button is not null"); } } @FXML private void onButtonClick(ActionEvent actionEvent) { } }