不能使用root.getChildrenUnmodifable（），只能使用root.getChildrenUnmodifable（）

Question

我现在的目标是创建一个网格，这将是我的游戏的基础。当玩家从菜单开始游戏时，这个网格应该出现在游戏场景上。稍后，我希望能够根据用户输入更改电路板的大小

1.在eventhandler中创建网格

我的推理是当玩家点击启动游戏的“SinglePlayer”按钮时创建网格。根据这个推理，我将简单地获取根节点（一个组）的子节点，并将gridpane添加到其中

为什么我被困住了

下面的代码段显示处理on button click事件的控制器。注释完后，我创建了一个按钮，获得了根节点，并使用了标准的getChildren（）.add（...）方法。然而，这是失败的。Intellij实际上建议使用getChildrenUnmodiable（）。根据我的理解，getChildrenUnmodifable（）是只读的，这不符合我的目的。我读到的问题是父母是受保护的，不能修改。那该去哪里修改呢？

@FXML
public void onButtonChangeScene(ActionEvent event) throws IOException {
    // Go to single player window
    if (event.getSource().equals(singleplayer)){
        Parent root = FXMLLoader.load(getClass().getResource("Views/board.fxml"));
        Scene rootscene = new Scene(root);

        //Get stage information
        Stage window = (Stage) ((Node)event.getSource()).getScene().getWindow();
        window.setScene(rootscene);


        // Creates the board
        Button button1 = new Button("Button 1");
        //Part that fails
        root.getchildren().add(button1);

        window.show();

fxml文件如下所示

Group xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="sample.BoardController">
   <children>
      <BorderPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0">
         <left>
            <AnchorPane prefHeight="200.0" prefWidth="200.0" BorderPane.alignment="CENTER">
               <children>
                  <Label alignment="CENTER" contentDisplay="CENTER" layoutY="6.0" prefHeight="17.0" prefWidth="200.0" text="Player 1">
                     <font>
                        <Font size="30.0" />
                     </font>
                  </Label>
                  <Label alignment="CENTER" contentDisplay="CENTER" layoutY="51.0" prefHeight="17.0" prefWidth="200.0" text="1200">
                     <font>
                        <Font size="30.0" />
                     </font>
                  </Label>
                  <Button fx:id="abandon" layoutX="71.0" layoutY="342.0" mnemonicParsing="false" onAction="#onButtonChangeScene" text="Abandon" />
               </children>
            </AnchorPane>
         </left>
         <right>
            <AnchorPane prefHeight="200.0" prefWidth="200.0" BorderPane.alignment="CENTER">
               <children>
                  <Label alignment="CENTER" contentDisplay="CENTER" layoutY="7.0" prefHeight="17.0" prefWidth="200.0" text="Player 2">
                     <font>
                        <Font size="30.0" />
                     </font>
                  </Label>
                  <Label alignment="CENTER" contentDisplay="CENTER" layoutY="52.0" prefHeight="17.0" prefWidth="200.0" text="800">
                     <font>
                        <Font size="30.0" />
                     </font>
                  </Label>
               </children>
            </AnchorPane>
         </right>
         <center>
            <GridPane fx:id="gridpane" BorderPane.alignment="CENTER">
              <columnConstraints>
                <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
                <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
              </columnConstraints>
              <rowConstraints>
                <RowConstraints 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>
               <children>
                  <ImageView fitHeight="118.0" fitWidth="99.0" pickOnBounds="true" preserveRatio="true">
                     <image>
                        <Image url="@../Images/bluecard.png" />
                     </image>
                  </ImageView>
                  <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true" GridPane.rowIndex="1" />
                  <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true" GridPane.columnIndex="1" GridPane.rowIndex="1" />
                  <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true" GridPane.rowIndex="2" />
                  <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true" GridPane.columnIndex="1" GridPane.rowIndex="2" />
               </children>
            </GridPane>
         </center>
      </BorderPane>
   </children>
</Group>

b）在FXML文件中静态创建，修改板的大小

2如何解决root.getChildren（）添加节点的问题？

Answer 1

您需要将.add（）与Pane一起使用，并且您的root不是一个Pane。

试试看

private BorderPane mainpane = (BorderPane)root.getchildren();
mainpane.add(gridpane);

或

<BorderPane fx:id = "mainpane" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0">

private BorderPane mainpane;
private GridPane gridpane;
mainpane.add(gridpane);