当返回java.lang.NullPointerException错误时，如何在java中使用setText更新FXML按钮？[副本]

Question

<AnchorPane xmlns:fx="http://javafx.com/fxml/1" fx:controller="project.Controller">
<Button fx:id="button" text="STOP"></Button> 
</AnchorPane>

public class project extends Application { 
    @Override
    public void start(Stage primaryStage) throws Exception {

        try {

            FXMLLoader loader = new FXMLLoader();
            loader.setLocation(project.class.getResource("index.fxml"));
             Parent root = loader.load();

            Scene scene = new Scene(root, 1200, 750);

            primaryStage.setScene(scene);
            primaryStage.show();

            Controller editButton = new Controller();
            editButton.editButtonText("blabla selected");


        } catch (Exception e){
            System.out.println(e);
        }  
    }

    public static void main(String[] args) {
        launch(args);
    }

}

类文件：

public class Controller implements Initializable
{   

    //FXML
   @FXML public Button button;


   @FXML
   public void editButtonText(String text){
    //   button = new Button();
       button.setText(text);
   }

   @Override
   public void initialize(URL url, ResourceBundle r){

   }
}

Answer 1

Controller editButton = new Controller();
editButton.editButtonText("blabla selected");

问题就在那部分。使用FXMLLoader加载fxml文件后，将自动创建一个新的控制器对象。您可以通过使用

Controller editButton = (Controller) loader.getController`

否则，您引用了一个新的controller，该controller没有为其分配GUI。

或者，您也可以将其写成：

Controller controller = new Controller();
FXMLLoader loader = new FXMLLoader();
loader.setLocation(project.class.getResource("index.fxml"));
loader.setController(controller);
Parent root = loader.load()