我是JavaFX的新手。我正在尝试构建一个示例大学管理应用程序，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 中的事件，该事件加载另一个fxml文件 newStudent.fxml ，该文件由 AdmissionController.java <处理/ p>
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();
}
}
AdmissionController.java
以下事件处理数据插入并关闭窗口，但在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();
}
我尝试在reloadStudentTable()内调用Controller.java方法，就像这样
Controller reloadData = new Controller();
reloadData.reloadStudentTable();
但它会产生一些这样的错误。
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
答案 0 :(得分：5)
控制器中的@FXML - 带注释的字段在加载FMXL时由FXMLLoader初始化。如果您手动创建一个新的控制器实例（即Controller reloadData = new Controller();），那么显然那些字段将不会在该控制器实例中初始化。
无论如何都无需调用reloadStudentTable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格的数据列表中：
data.add(new StudentMaster(...));
为了做到这一点，您只需要AdmissionController来引用数据：
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();
}
// ...
}
然后在你的主控制器中执行：
@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();
}
}