JavaFX FXML修改列表

Question

我正在开发一个项目，并希望有一个菜单供用户添加和删除项目。我已经看到了在你的菜单对象上使用getItems的java文档，但是这给了我一个在运行时出现空点错误的情况。“由于：java.lang.NullPointerException at app.Main_Controller.PopulateModelBarAdd（Main_Controller.java:257）”

<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.91" xmlns:fx="http://javafx.com/fxml/1" fx:controller="app.Main_Controller"> 
    <children> 
     <VBox layoutX="-1.0" layoutY="39.0" prefHeight="361.0" prefWidth="270.0"> 
     <children> 
      <HBox prefHeight="37.0" prefWidth="270.0"> 
       <children> 
        <TextField fx:id="VarientAdminPanelText" promptText="Varient" /> 
        <Button fx:id="RemoveVarAdminPanel" mnemonicParsing="false" text="Remove" /> 
        <Button fx:id="AddVarAdminPanel" mnemonicParsing="false" text="Add " onAction= "#PopulateModelBarAdd"/> 
       </children> 
      </HBox> 
      <HBox prefHeight="33.0" prefWidth="270.0"> 
       <children> 
        <TextField fx:id="XCordAdminPanel" promptText="X codinate" /> 
        <TextField fx:id="YCordAdminPanel" promptText="Y Cordinate" /> 
        <TextField fx:id="ZCordAdminPanel" promptText="Z Cordinate" /> 
       </children> 
      </HBox> 
      <HBox prefHeight="262.0" prefWidth="270.0"> 
       <children> 
        <Button fx:id="AddCordAdminPanel" mnemonicParsing="false" prefHeight="25.0" prefWidth="135.0" text="Add" /> 
        <Button fx:id="RemoveCordAdminPanel" mnemonicParsing="false" prefHeight="25.0" prefWidth="139.0" text="Remove" /> 
       </children> 
      </HBox> 
      <Button fx:id="AdminBack" mnemonicParsing="false" onAction="#HandelAdminVeiwMain" text="Back To Main Veiw" /> 
     </children> 
     </VBox> 
     <HBox layoutX="4.0" prefHeight="32.0" prefWidth="600.0"> 
     <children> 
      <Text strokeType="OUTSIDE" strokeWidth="0.0" text="Admin Panel"> 
       <font> 
        <Font name="Calibri" size="34.0" /> 
       </font> 
      </Text> 
     </children> 
     </HBox> 
     <VBox layoutX="279.0" prefHeight="400.0" prefWidth="321.0" /> 
    </children> 
</AnchorPane> 

的FXML文件，其中所述菜单是：

<GridPane hgap="14.0" maxHeight="+Infinity" maxWidth="+Infinity" minHeight="-Infinity" minWidth="-Infinity" vgap="20.0" xmlns="http://javafx.com/javafx/8.0.91" xmlns:fx="http://javafx.com/fxml/1" fx:controller="app.Main_Controller"> 
    <children> 
    <ImageView fitHeight="61.0" fitWidth="60.0" pickOnBounds="true" preserveRatio="true" GridPane.columnIndex="0" GridPane.halignment="CENTER" GridPane.rowIndex="0" GridPane.valignment="TOP"> 
     <image> 
     <!-- place holder --> 
     </image> 
    </ImageView> 
    <VBox maxHeight="+Infinity" maxWidth="+Infinity" minHeight="-Infinity" prefWidth="400.0" spacing="7.0" GridPane.columnIndex="1" GridPane.rowIndex="0"> 
     <children> 
     <Label fx:id="messageLabel" text="Remove from Buffer" textAlignment="LEFT" wrapText="true"> 
      <font> 
      <Font name="System Bold" size="13.0" /> 
      </font> 
     </Label> 
     <Label fx:id="detailsLabel" textAlignment="LEFT" wrapText="true"> 
      <font> 
      <Font size="12.0" /> 
      </font> 
     </Label> 
      <SplitMenuButton fx:id="RemoveVarMenu" mnemonicParsing="false" prefHeight="25.0" prefWidth="96.0" text="Model"> 
       <items> 
        <Menu fx:id="test" mnemonicParsing="false" text="Unspecified Menu"> 
        <items> 
         <MenuItem mnemonicParsing="false" text="Action 1" /> 
        </items> 
        </Menu> 
        <MenuItem mnemonicParsing="false" text="Alasdair" /> 
       </items></SplitMenuButton> 
     </children> 
    </VBox> 
    <HBox maxHeight="-Infinity" maxWidth="+Infinity" minHeight="-Infinity" minWidth="-Infinity" GridPane.columnIndex="1" GridPane.rowIndex="1"> 
     <children> 
     <HBox fx:id="actionParent" alignment="CENTER"> 
      <HBox.margin> 
      <Insets /> 
      </HBox.margin> 
     </HBox> 
     <Pane maxWidth="+Infinity" HBox.hgrow="ALWAYS"> 
       <children> 
        <TextField fx:id="RemoveNumTextFeild" prefHeight="25.0" prefWidth="96.0" promptText="num to remove" /> 
       </children></Pane> 
     <Button fx:id="RemoveCancelButton" cancelButton="true" minWidth="80.0" mnemonicParsing="false" onAction="#HandelRemoveMain" text="Cancel" HBox.hgrow="NEVER"> 
      <HBox.margin> 
      <Insets /> 
      </HBox.margin> 
     </Button> 
     <HBox fx:id="okParent" alignment="CENTER"> 
      <children> 
      <Button fx:id="okButtonRemove" minWidth="80.0" mnemonicParsing="false" onAction="#HandelRemoveToBufferPopup" text="Ok" HBox.hgrow="NEVER"> 
       <HBox.margin> 
       <Insets left="14.0" /> 
       </HBox.margin> 
      </Button> 
      </children> 
     </HBox> 
     </children> 
    </HBox> 
    </children> 
    <columnConstraints> 
    <ColumnConstraints hgrow="NEVER" maxWidth="55.0" minWidth="-Infinity" prefWidth="0.0" /> 
    <ColumnConstraints halignment="CENTER" hgrow="ALWAYS" maxWidth="Infinity" minWidth="-Infinity" prefWidth="460.0" /> 
    </columnConstraints> 
    <padding> 
    <Insets bottom="14.0" left="14.0" right="14.0" top="14.0" /> 
    </padding> 
    <rowConstraints> 
    <RowConstraints maxHeight="+Infinity" minHeight="-Infinity" valignment="CENTER" vgrow="ALWAYS" /> 
    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" /> 
    </rowConstraints> 
</GridPane> 

在控制器中使用的代码看起来像

@FXML 
    public Menu test; 
    public TextField VarientAdminPanelText; 
    public void PopulateModelBarAdd(){ 
     MenuItem item = new MenuItem(VarientAdminPanelText.getText()); 
     System.out.println(test.getItems()); 
     test.getItems().addAll(item); 
    } 

氏小号让我wounder如果它甚至有可能修改GUI时，它是基于关闭FXML的

Answer 1

我解决这个问题的方法是在initialize方法来初始化菜单项

public void initialize(URL location, ResourceBundle resources) { 
    java.util.Iterator<String> itr = BufferManipulation.Menu.iterator(); 
    while(itr.hasNext()){ 
     AddVarMenu.getItems().addAll(new MenuItem(itr.next())); 
     } 
    java.util.Iterator<MenuItem> Item = AddVarMenu.getItems().iterator(); 
    while(Item.hasNext()){ 
     MenuItem MenuFeild = Item.next(); 
     MenuFeild.setOnAction(e -> AddVarMenu.setText(MenuFeild.getText())); 
    } 

    System.out.println("Inventory view is now loaded!"); 
} 

这个问题似乎是我们无法修改场景，因此我们只需将菜单项放置在一个对象中，我们可以从控制器传递给控制器​​，即在一个对象中进行修改，然后将其加载到另一个对象中

Answer 2

更改代码

public Menu test; 
@FXML //define FXML for VarientAdminPanelText 
public TextField VarientAdminPanelText; 

    public void PopulateModelBarAdd(){ 
     MenuItem item = new MenuItem(VarientAdminPanelText.getText()); 
     System.out.println(test.getItems()); 
     test.getItems().addAll(item); 
    } 

，我没有看到任何外汇：测试id元素，如果你之外声明它FXML那么你需要将其初始化为

Menu test=new Menu()