java - 当我在 initialize() 方法中添加 TableView 功能时，按钮停止工作

Question

在我将表格（TableView）功能添加到我的代码之前，我的按钮运行良好，但是现在一旦我单击相同的按钮就会发生错误。如果我在以下代码中注释掉这行代码，错误就会消失并且按钮可以工作RoomsController：

intRoomIDColVR.setCellValueFactory(new PropertyValueFactory<>("roomID"));
vachRoomTypeIDColVR.setCellValueFactory(new PropertyValueFactory<>("roomTypeID"));
roomTableViewVR.setItems(olRoomData);

FXML 文件：

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>

<AnchorPane id="AnchorPane" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.codetech.hotelmis.controller.RoomsController">
    <children>
      <BorderPane prefHeight="338.0" prefWidth="600.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
        <center>
          <Accordion BorderPane.alignment="CENTER">
            <panes>
              <TitledPane fx:id="accVacant" animated="false" text="Vacant Rooms">
                <content>
                  <AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="180.0" prefWidth="200.0">
                    <children>
                              <BorderPane prefHeight="324.0" prefWidth="598.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
                                 <center>
                            <TableView fx:id="roomTableViewVR" BorderPane.alignment="CENTER">
                              <columns>
                                <TableColumn fx:id="intRoomIDColVR" prefWidth="75.0" text="Room ID" />
                                <TableColumn fx:id="vachRoomTypeIDColVR" prefWidth="115.00000762939453" text="Room Type" />
                                          <TableColumn fx:id="reservedColVR" prefWidth="94.0" text="Reserved?" />
                                          <TableColumn fx:id="resCustomerColVR" prefWidth="95.0" text="Customer " />
                              </columns>
                            </TableView>
                                 </center>
                                 <top>
                                    <HBox>
                                       <children>
                                          <Button fx:id="btnCheckInPopUp" mnemonicParsing="false" text="Check In" BorderPane.alignment="CENTER" />
                                       </children>
                                    </HBox>
                                 </top>
                              </BorderPane>
                    </children>
                  </AnchorPane>
                </content>
              </TitledPane>
              <TitledPane fx:id="accOccupied" animated="false" text="Occupied Rooms">
                <content>
                  <AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="180.0" prefWidth="200.0">
                    <children>
                              <BorderPane prefHeight="324.0" prefWidth="598.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
                                 <top>
                                    <HBox>
                                       <children>
                                          <Button fx:id="btnTabCheckOut" mnemonicParsing="false" text="Check Out" BorderPane.alignment="CENTER" />
                                       </children>
                                    </HBox>
                                 </top>
                                 <center>
                                    <TableView BorderPane.alignment="CENTER">
                                       <columns>
                                          <TableColumn fx:id="intRoomIDColOR" prefWidth="75.0" text="Room ID" />
                                          <TableColumn fx:id="vachRoomTypeIDColOR" prefWidth="115.00000762939453" text="Room Type" />
                                          <TableColumn fx:id="occupantColOR" prefWidth="83.0" text="Occupant" />
                                          <TableColumn fx:id="checkInDateColOR" prefWidth="121.0" text="Check In Date" />
                                          <TableColumn fx:id="checkOutDateColOR" prefWidth="181.99996948242188" text="Expected Check Out Date" />
                                       </columns>
                                    </TableView>
                                 </center>
                              </BorderPane>
                    </children>
                  </AnchorPane>
                </content>
              </TitledPane>
            </panes>
          </Accordion>
        </center>
        <top>
          <HBox prefHeight="24.0" prefWidth="600.0" BorderPane.alignment="CENTER">
            <children>
              <Button fx:id="btnNewRoom" mnemonicParsing="false" text="New Room" />
              <Button fx:id="btnEditRoom" mnemonicParsing="false" text="Edit Room" />
                  <Button fx:id="btnNewRoomType" mnemonicParsing="false" text="New Room Type" />
                  <Button fx:id="btnEditRoomType" mnemonicParsing="false" text="Edit Room Type" />
                  <Button fx:id="btnGuestLog" mnemonicParsing="false" text="Guest Log" />
            </children>
          </HBox>
        </top>
      </BorderPane>
    </children>
</AnchorPane>

控制器类：

    public class RoomsController implements Initializable {
    @FXML
    private TableView<RoomData> roomTableViewVR;
    @FXML
    private TableColumn<RoomData, Integer> intRoomIDColVR;
    @FXML
    private Button btnCheckInPopUp;
    @FXML
    private TableColumn<RoomData, String> vachRoomTypeIDColVR;

    //Declare ObservableList
    private ObservableList<RoomData> olRoomData;

    private ActionEvent event;
    private static Connection con;
    private static ResultSet rs;
    private static java.sql.Statement stmt;
    private static String sql;
    JavaToMySQL javaToMySQL = new JavaToMySQL();

    public RoomsController() {
        try {
            con = DatabaseConnection.getConnected();
            stmt = con.createStatement();
            olRoomData = FXCollections.observableArrayList();
            rs = con.createStatement().executeQuery("SELECT * FROM h_r_rooms");
            while (rs.next()){
                olRoomData.add(new RoomData(rs.getInt("intRoomID"),rs.getString("vachRoomTypeID")));
            }
        } catch (SQLException e) {
            e.printStackTrace();
            System.out.println("Error on Building Data");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void initialize(URL location, ResourceBundle resources) {
        listeners();

        intRoomIDColVR.setCellValueFactory(new PropertyValueFactory<>("roomID"));
        vachRoomTypeIDColVR.setCellValueFactory(new PropertyValueFactory<>("roomTypeID"));
        roomTableViewVR.setItems(olRoomData);
    }

    void listeners(){
        btnCheckInPopUp.setOnAction((event -> {
            System.out.println("I'm supposed to pop out a Check In window when you click me!");

            Stage stage;
            if (event.getSource()== btnCheckInPopUp){
                stage = new Stage();
                try {
                    Parent root = FXMLLoader.load(getClass().getResource("../view/popups/check_in.fxml"));
                    System.out.println("I work!");
                    stage.setScene(new Scene(root));
                    stage.setTitle("Check Customer In");
                    stage.initModality(Modality.APPLICATION_MODAL);
                    stage.initOwner(btnCheckInPopUp.getScene().getWindow());
                    stage.showAndWait();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }));
    }
}

当我单击 Check In( btnCheckInPopUp) 时，会出现以下错误：

The Connection is open!
javafx.fxml.LoadException: 
/home/mush/Programming/Dev/InteliJProjects/Hotel_MIS/out/production/Hotel_MIS/com/codetech/hotelmis/view/popups/check_in.fxml

    at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2605)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2583)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2445)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3218)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3179)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3152)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3128)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3108)
    at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3101)
    at com.codetech.hotelmis.controller.RoomsController.lambda$listeners$0(RoomsController.java:87)
    at com.codetech.hotelmis.controller.RoomsController$$Lambda$104/1394020985.handle(Unknown Source)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
    at javafx.event.Event.fireEvent(Event.java:198)
    at javafx.scene.Node.fireEvent(Node.java:8390)
    at javafx.scene.control.Button.fire(Button.java:185)
    at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
    at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.event.Event.fireEvent(Event.java:198)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3758)
    at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3486)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2495)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:350)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:275)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$350(GlassViewEventHandler.java:385)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$$Lambda$252/507580015.get(Unknown Source)
    at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:404)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:384)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
    at com.sun.glass.ui.View.notifyMouse(View.java:927)
    at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
    at com.sun.glass.ui.gtk.GtkApplication.lambda$null$48(GtkApplication.java:139)
    at com.sun.glass.ui.gtk.GtkApplication$$Lambda$43/1166661505.run(Unknown Source)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
    at com.codetech.hotelmis.controller.RoomsController.initialize(RoomsController.java:74)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2552)
    ... 70 more

我真的试图找出原因，但无济于事。我非常感谢您的帮助，我将提供有关解决问题所需代码的更多详细信息。

这里的问题似乎和我的很相似。

score 1 · Accepted Answer

您似乎对两个不同的 FXML 文件使用相同的控制器类。不要这样做：为每个 FXML 使用不同的控制器。

当FXMLLoader'load()方法被调用时，它会执行以下操作（有些简化的描述）：

读取 FXML 文件
如果 FXML 文件指定了控制器类，它会通过调用其无参数构造函数来创建控制器类的新实例
基于 FXML 元素创建对象层次结构
在元素上设置事件处理程序，映射到在步骤 1 中创建的控制器类实例
对于具有fx:id属性的元素，它将相应的对象注入到@FXML控制器实例中任何匹配的带注释的引用中
如果存在这样的方法，则调用initialize()控制器实例。
返回与 FXML 文件的根元素对应的对象。

在您的情况下，您有两个 FXML 文件指定相同的控制器类。当加载“主”FXML 文件时，就会发生上述过程。RoomsController创建第一个实例，注入与 s@FXML匹配的带注释的字段fx:id（包括intRoomIDColVR和其他），注册事件处理程序，并initialize()调用该方法。此时一切都很好。

当btnCheckInPopup按钮被按下时，它的onAction处理程序被调用。这会导致check_in.fxml加载。由于这指定了相同的控制器类，因此创建了该类的第二个实例。注入与 with 匹配的@FXML元素对应的带注释的字段。但是，请注意，因为没有用定义任何元素，所以没有为第二个控制器实例初始化。然后在第二个控制器实例上调用该方法，并且由于没有初始化，这会导致 a at the linecheck_in.fxmlfx:idcheck_in.fxmlfx_id="intRoomIDColVR"intRoomIDColVRinitialize()intRoomIDColVRNullPointerException

intRoomIDColVR.setCellValueFactory(new PropertyValueFactory<>("roomID"));

这是一个很好的例子，说明了为什么每个 FXML 都应该有自己的控制器类。如果您像这样“共享”控制器类，则很难跟踪哪些字段已初始化，哪些未在任何给定时间初始化，以及对于该类的任何特定实例。

java - 当我在 initialize() 方法中添加 TableView 功能时，按钮停止工作

1 回答 1

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