那些遇到过的问题

如何在插入新数据后重新加载JavaFX tableview？

nit*_*man 1 java javafx

我是JavaFX的新手.我正在尝试构建一个示例性的大学管理应用程序,其中我有一个带有表视图的仪表板(dashboard.fxml)来填充学生数据.

有一个按钮可以加载(newStduent.fxml)学生数据输入窗口并存储到数据库中.我需要在数据插入表后自动重新加载表.

以下代码处理Controller.java中的Event ,它加载另一个fxml文件newStudent.fxml,由AdmissionController.java处理 

    public void buildData(String SQL)
    {
        data = FXCollections.observableArrayList();
        try {
            ResultSet rs = connection.createStatement().executeQuery(SQL);
            while(rs.next())
            {
                StudentMaster studentData = new StudentMaster();
                studentData.studentId.set(rs.getInt("student_id"));
                studentData.stdClass.set(rs.getString("student_std"));
                studentData.name.set(rs.getString("student_name"));
                studentData.admNo.set(rs.getString("student_admn_no"));
                studentData.regno.set(rs.getString("student_regno"));
                studentData.stdDiv.set(rs.getString("student_div"));
                data.add(studentData);
                studentTable.setItems(data);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    @FXML
    void initialize() {
        assert studentTable != null : "fx:id=\"studentTable\" was not injected: check your FXML file 'dashboard.fxml'.";
        assert studID != null : "fx:id=\"studID\" was not injected: check your FXML file 'dashboard.fxml'.";
        assert studReg != null : "fx:id=\"studReg\" was not injected: check your FXML file 'dashboard.fxml'.";
        assert stdAdm != null : "fx:id=\"stdAdm\" was not injected: check your FXML file 'dashboard.fxml'.";
        assert stdName != null : "fx:id=\"stdName\" was not injected: check your FXML file 'dashboard.fxml'.";
        assert stdClass != null : "fx:id=\"stdClass\" was not injected: check your FXML file 'dashboard.fxml'.";
        assert stdDiv != null : "fx:id=\"stdDiv\" was not injected: check your FXML file 'dashboard.fxml'.";

        loadDataToTable();

        DatabaseAccess newConnection = new DatabaseAccess();
        connection = newConnection.startConnection();
        String SQL = "Select * from student";
        buildData(SQL);
        newConnection.shutdown();

    }

    private void loadDataToTable()
    {
        studID.setCellValueFactory(new PropertyValueFactory<StudentMaster, Integer>("studentId"));
        studReg.setCellValueFactory(new PropertyValueFactory<StudentMaster, String>("regno"));
        stdName.setCellValueFactory(new PropertyValueFactory<StudentMaster, String>("name"));
        stdAdm.setCellValueFactory(new PropertyValueFactory<StudentMaster, String>("admNo"));
        stdClass.setCellValueFactory(new PropertyValueFactory<StudentMaster, String>("stdClass"));
        stdDiv.setCellValueFactory(new PropertyValueFactory<StudentMaster, String>("stdDiv"));
    }

    @FXML
    void createStudent(ActionEvent event)
    {
        FXMLLoader fxmlLoader;
        fxmlLoader = new FXMLLoader(getClass().getResource("/resources/fxml/newStudent.fxml"));
        try {
            Parent root1 = (Parent)fxmlLoader.load();
            Stage stage = new Stage();
            stage.initModality(Modality.APPLICATION_MODAL);
//            stage.initStyle(StageStyle.UNDECORATED);
            stage.setTitle("New Admission");
            stage.setScene(new Scene(root1));
            stage.show();
        } catch (IOException e)
        {
            e.printStackTrace();
        }
    }

    @FXML
    void searchBtnClicked(ActionEvent event)
    {
        String name = nameBox.getText();
        String regno = regBox.getText();
        String admno = admBox.getText();
        String stdClass = classBox.getText();

        String SQL = "Select * from student where student_name like '"+name+"%'";
        System.out.println(SQL);
        DatabaseAccess newConnection = new DatabaseAccess();
        connection = newConnection.startConnection();
        buildData(SQL);
        newConnection.shutdown();
        loadDataToTable();
    }

    public void reloadStudentTable()
    {
        loadDataToTable();
    }

}
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AdmissionController.java

以下事件处理数据插入并关闭窗口,但插入后不会更新表视图.

@FXML
    void doneBtnClicked(ActionEvent event)
    {
        String name = nameBox.getText();
        String SQLquery = "INSERT INTO student (student_name) VALUES ('"+name+"')";
        ExecuteSQL newQuery = new ExecuteSQL();
        Boolean executeStatus = newQuery.ExecuteSQL(SQLquery);
        System.out.println(executeStatus ? "Data Inserted" : "Error in execution");    


        //        Close the Window after successfully inserted

        Node node = (Node)event.getSource();
        Stage stage = (Stage)node.getScene().getWindow();
        stage.close();
    }
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我试着像这样调用这个reloadStudentTable()方法Controller.java

Controller reloadData = new Controller();
reloadData.reloadStudentTable();
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但它产生了一些像这样的错误.

    Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1774)
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1657)
    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.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:8411)
    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.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$MouseHandler.process(Scene.java:3757)
    at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:352)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:275)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:388)
Data Inserted
    at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:387)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
    at com.sun.glass.ui.View.notifyMouse(View.java:937)
    at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
    at com.sun.glass.ui.gtk.GtkApplication.lambda$null$49(GtkApplication.java:139)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
    at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
    at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1769)
    ... 48 more
Caused by: java.lang.NullPointerException
    at dashboard.Controller.loadDataToTable(Controller.java:132)
    at dashboard.Controller.reloadStudentTable(Controller.java:178)
    at dashboard.AdmissionController.doneBtnClicked(AdmissionController.java:72)
    ... 58 more
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Jam*_*s_D 5

该@FXML控制器中的-annotated字段由FXMLLoader当它加载FMXL初始化.如果您手动创建一个新的控制器实例(即Controller reloadData = new Controller();),那么显然这些字段将不会在该控制器实例中初始化.

reloadStudentTable无论如何都不需要调用该方法.它所做的只是配置列,以便他们知道要显示哪些数据; 你不需要多次这样做.您需要做的就是将新学生添加到表的数据列表中:

data.add(new StudentMaster(...));
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为此,您只需要AdmissionController对数据进行引用:

public class AdmissionController {

    private ObservableList<StudentMaster> data ;

    public void setStudentData(ObservableList<StudentMaster> data) {
        this.data = data ;
    }

    // existing code...

    @FXML
    void doneBtnClicked(ActionEvent event)
    {
        String name = nameBox.getText();
        String SQLquery = "INSERT INTO student (student_name) VALUES ('"+name+"')";
        ExecuteSQL newQuery = new ExecuteSQL();
        boolean executeStatus = newQuery.ExecuteSQL(SQLquery);
        System.out.println(executeStatus ? "Data Inserted" : "Error in execution");    

        if (executeStatus) {
            StudentMaster student = new StudentMaster(...);
            data.add(student);
        }

        //        Close the Window after successfully inserted

        Node node = (Node)event.getSource();
        Stage stage = (Stage)node.getScene().getWindow();
        stage.close();
    }  

    // ...
}
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然后在你的主控制器中做:

@FXML
void createStudent(ActionEvent event)
{
    FXMLLoader fxmlLoader;
    fxmlLoader = new FXMLLoader(getClass().getResource("/resources/fxml/newStudent.fxml"));
    try {
        Parent root1 = (Parent)fxmlLoader.load();

        AdmissionController admissionController = fxmlLoader.getController();
        admissionController.setStudentData(studentTable.getItems());

        Stage stage = new Stage();
        stage.initModality(Modality.APPLICATION_MODAL);
        stage.setTitle("New Admission");
        stage.setScene(new Scene(root1));
        stage.show();
    } catch (IOException e)
    {
        e.printStackTrace();
    }
}
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