Question

在我的FXML中，我创建了一个gridpane。现在我要添加动态元素（如按钮，文本字段）通过java代码（而不是FXML），虽然我试图这样做，但我收到错误。请帮助。

我的FXML：

    <AnchorPane fx:controller="tableview.TableViewSample" id="AnchorPane" maxHeight="-     Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns:fx="http://javafx.com/fxml">
  <children>
    <GridPane fx:id="greadpane" layoutX="0.0" layoutY="0.0" prefHeight="400.0" prefWidth="600.0">
      <columnConstraints>
        <ColumnConstraints fx:id="col0" hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
        <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
      </columnConstraints>
      <rowConstraints>
        <RowConstraints  fx:id="row0" minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
        <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
        <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
      </rowConstraints>
    </GridPane>
  </children>
    </AnchorPane>

我的Java代码：

    public class TableViewSample extends Application {

    @FXML private GridPane greadpane;
  public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage stage) throws IOException {

        Pane myPane = (Pane)FXMLLoader.load(getClass().getResource
                ("tabviewexamlpe.fxml"));
        Scene scene = new Scene(myPane);
        stage.setTitle("Table View ");
        stage.setWidth(450);
        stage.setHeight(500);
        stage.setScene(scene);       

        final Label label = new Label("Address Book");
        label.setFont(new Font("Arial", 20));
        greadpane.add(label, 0, 0);
        stage.show();
}
}

Answer 1

你得到一个空指针，因为你试图在stage.show（）之前进行操作，所以fxml尚未初始化。不做脏事并将你的greadPane.add放在一个单独的控制器上

public class Controller implements Initializable {

    @FXML
    private GridPane greadpane;

    @Override
    public void initialize(URL url, ResourceBundle resourceBundle) {
        final Label label = new Label("Address Book");
        label.setFont(new Font("Arial", 20));
        greadpane.add(label, 0, 0);
    }
}

并将您的fxml指定给此控制器。它会没事的

Answer 2

我遇到了同样的问题并使用了Agonist_建议，但是我没有将gridPane分成新的控制器，而是创建了一个运行10ms以后执行等待stage.show（）的代码的线程。

public GameController(Game game) {
    game.addObserver(this);
    new Thread() {
        @Override
        public void run() {
            try {
                Thread.sleep(10);
                Platform.runLater(() -> {
                    game.startBeginnerRound();
                });
            } catch (InterruptedException ex) {
                Logger.getLogger(GameController.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }.start();
}

在此示例中，当observable通知它时更新gridPane，在这种情况下执行game.startBeginnerRound（）。

JAVAFX在FXML Gridpane中添加动态元素

2 个答案: