我使用数据库中的数据填充TableView。当我在TableView中选择一行（Tableview具有监听器），然后再次重新填充TableView时，数据填充成功但发生了NPE。
我希望我能表达清楚。
很抱歉这篇长篇文章。
的ActionEvent
@FXML
private void searchEmployee(ActionEvent event)
{
Stage imageUploadStage = (Stage) ((Node) event.getSource()).getScene().getWindow();
Alert alert = new Alert(Alert.AlertType.ERROR);
alert.initOwner(imageUploadStage);
if(employeeTextField.getText().isEmpty())
{
alert.setTitle("Insufficient Data");
alert.setHeaderText("Lacking search input");
alert.setContentText("Looks like you forgot to input in the search box!");
alert.showAndWait();
employeeTextField.requestFocus();
}
else
{
final Service<ObservableList<Employee>> service = new Service<ObservableList<Employee>>()
{
@Override
protected Task<ObservableList<Employee>> createTask()
{
return new Task<ObservableList<Employee>>()
{
@Override
protected ObservableList<Employee> call() throws Exception
{
ObservableList<Employee> items = FXCollections.observableArrayList();
try
{
Connection c;
PreparedStatement pst;
ResultSet rs;
c = connect();
String SQL = "SELECT " +
"B1_ID, " +
"Emp_Fname, " +
"Emp_Lname, " +
"Emp_Position, " +
"Emp_ContactNo, " +
"Emp_Address, " +
"Emp_BirthDate, " +
"Image " +
"FROM pay_employee_tbl " +
"WHERE pay_employee_tbl.Emp_Lname LIKE ?";
pst = c.prepareStatement(SQL);
pst.setString(1, employeeTextField.getText() + "%");
rs = pst.executeQuery();
while(rs.next())
{
items.add(new Employee(rs.getString("B1_ID"),
rs.getString("Emp_Fname"),
rs.getString("Emp_Lname"),
rs.getString("Emp_Position"),
rs.getString("Emp_ContactNo"),
rs.getString("Emp_Address"),
rs.getString("Emp_BirthDate")));
}
c.close();
pst.close();
rs.close();
}
catch(Exception e)
{
Logger.getLogger(FxmlControllerCLB.class.getName()).log(Level.SEVERE, null, e);
}
for (int i = 0; i < 250; i++)
{
updateProgress(i, 250);
Thread.sleep(2);
}
return items;
}
};
}
};
progressIndicator.visibleProperty().bind(service.runningProperty());
progressIndicator.progressProperty().bind(service.progressProperty());
veil.visibleProperty().bind(service.runningProperty());
employeeTextField.disableProperty().bind(service.runningProperty());
uploadImageButton.disableProperty().bind(service.runningProperty());
employeeTableView.itemsProperty().bind(service.valueProperty());
service.start();
}
}
数据模型
public class Employee
{
private SimpleStringProperty bioKeyID;
private SimpleStringProperty Fname;
private SimpleStringProperty Lname;
private SimpleStringProperty position;
private SimpleStringProperty contactNo;
private SimpleStringProperty address;
private SimpleStringProperty birthDate;
private Employee()
{
}
public Employee(String bioKeyID, String Fname, String Lname,
String position, String contactNo, String address,
String birthDate)
{
this.bioKeyID = new SimpleStringProperty(bioKeyID);
this.Fname = new SimpleStringProperty(Fname);
this.Lname = new SimpleStringProperty(Lname);
this.position = new SimpleStringProperty(position);
this.contactNo = new SimpleStringProperty(contactNo);
this.address = new SimpleStringProperty(address);
this.birthDate = new SimpleStringProperty(birthDate);
}
public String getBioKeyID()
{
return bioKeyID.get();
}
public void setBioKeyID(String bioKeyID)
{
this.bioKeyID.set(bioKeyID);
}
public StringProperty bioKeyIDProperty()
{
return bioKeyID;
}
public String getFname()
{
return Fname.get();
}
public void setFname(String Fname)
{
this.Fname.set(Fname);
}
public StringProperty FnameProperty()
{
return Fname;
}
public String getLname()
{
return Lname.get();
}
public void setLname(String Lname)
{
this.Lname.set(Lname);
}
public StringProperty LnameProperty()
{
return Lname;
}
public String getPosition()
{
return position.get();
}
public void setPosition(String position)
{
this.position.set(position);
}
public StringProperty positionProperty()
{
return position;
}
public String getContactNo()
{
return contactNo.get();
}
public void setContactNo(String contactNo)
{
this.contactNo.set(contactNo);
}
public StringProperty contactNoProperty()
{
return contactNo;
}
public String getAddress()
{
return address.get();
}
public void setAddress(String address)
{
this.address.set(address);
}
public StringProperty addressProperty()
{
return address;
}
public String getBirthDate()
{
return birthDate.get();
}
public void setBirthDate(String birthDate)
{
this.birthDate.set(birthDate);
}
public SimpleStringProperty birthDateProperty()
{
return birthDate;
}
}
TableColumn和TableView侦听器
public void initialize(URL url, ResourceBundle rb)
{
progressIndicator.setVisible(false);
progressBar.setVisible(false);
veil.setVisible(false);
TableColumn bioKeyID = new TableColumn("BioKey ID");
bioKeyID.setCellValueFactory(new PropertyValueFactory("bioKeyID"));
TableColumn empFName = new TableColumn("First Name");
empFName.setCellValueFactory(new PropertyValueFactory("Fname"));
TableColumn empLName = new TableColumn("Last Name");
empLName.setCellValueFactory(new PropertyValueFactory("Lname"));
TableColumn empName = new TableColumn("Employee Name");
empName.getColumns().addAll(empFName,empLName );
TableColumn position = new TableColumn("Position");
position.setCellValueFactory(new PropertyValueFactory("position"));
TableColumn contactNo = new TableColumn("Contact No");
contactNo.setCellValueFactory(new PropertyValueFactory("contactNo"));
TableColumn address = new TableColumn("Address");
address.setCellValueFactory(new PropertyValueFactory("Address"));
TableColumn birthDate = new TableColumn("Birth Date");
birthDate.setCellValueFactory(new PropertyValueFactory("birthDate"));
employeeTableView.getColumns().addAll(bioKeyID, empName, position,
contactNo, address, birthDate);
employeeTableView.getSelectionModel().selectedItemProperty().addListener((ObservableValue<? extends Employee> observableValue, Employee oldValue, Employee newValue) ->
{ //THIS IS LINE 415
if(employeeTableView.getSelectionModel().selectedItemProperty() != null)
{
empBioKeyLabel.setText(newValue.getBioKeyID());
empNameLabel.setText(newValue.getLname() + ", " + newValue.getFname());
empPositionLabel.setText(newValue.getPosition());
empContactNoLabel.setText(newValue.getContactNo());
}
}
}
栈跟踪
Executing D:\NetBeansProjects\PhotoUpload\dist\run1983452311\ImageUpload.jar using platform C:\Program Files\Java\jdk1.8.0_45\jre/bin/java
Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
at controller.FxmlControllerHRLedger.lambda$initialize$0(FxmlControllerHRLedger.java:415)
at controller.FxmlControllerHRLedger$$Lambda$240/27188331.changed(Unknown Source)
at com.sun.javafx.binding.ExpressionHelper$SingleChange.fireValueChangedEvent(ExpressionHelper.java:182)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
at javafx.beans.property.ReadOnlyObjectWrapper$ReadOnlyPropertyImpl.fireValueChangedEvent(ReadOnlyObjectWrapper.java:176)
at javafx.beans.property.ReadOnlyObjectWrapper.fireValueChangedEvent(ReadOnlyObjectWrapper.java:142)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:112)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:146)
at javafx.scene.control.SelectionModel.setSelectedItem(SelectionModel.java:102)
at javafx.scene.control.MultipleSelectionModelBase.lambda$new$34(MultipleSelectionModelBase.java:67)
at javafx.scene.control.MultipleSelectionModelBase$$Lambda$219/19068940.invalidated(Unknown Source)
at com.sun.javafx.binding.ExpressionHelper$SingleInvalidation.fireValueChangedEvent(ExpressionHelper.java:137)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
at javafx.beans.property.ReadOnlyIntegerWrapper$ReadOnlyPropertyImpl.fireValueChangedEvent(ReadOnlyIntegerWrapper.java:176)
at javafx.beans.property.ReadOnlyIntegerWrapper.fireValueChangedEvent(ReadOnlyIntegerWrapper.java:142)
at javafx.beans.property.IntegerPropertyBase.markInvalid(IntegerPropertyBase.java:113)
at javafx.beans.property.IntegerPropertyBase.set(IntegerPropertyBase.java:147)
at javafx.scene.control.SelectionModel.setSelectedIndex(SelectionModel.java:68)
at javafx.scene.control.TableView$TableViewArrayListSelectionModel.updateSelectedIndex(TableView.java:2900)
at javafx.scene.control.TableView$TableViewArrayListSelectionModel.clearSelection(TableView.java:2694)
at controller.FxmlControllerHRLedger.searchEmployee(FxmlControllerHRLedger.java:274)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1765)
at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1653)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Node.fireEvent(Node.java:8390)
at com.sun.javafx.scene.control.behavior.TextFieldBehavior.fire(TextFieldBehavior.java:179)
at com.sun.javafx.scene.control.behavior.TextInputControlBehavior.callAction(TextInputControlBehavior.java:178)
at com.sun.javafx.scene.control.behavior.BehaviorBase.callActionForEvent(BehaviorBase.java:218)
at com.sun.javafx.scene.control.behavior.TextInputControlBehavior.callActionForEvent(TextInputControlBehavior.java:127)
at com.sun.javafx.scene.control.behavior.BehaviorBase.lambda$new$75(BehaviorBase.java:135)
at com.sun.javafx.scene.control.behavior.BehaviorBase$$Lambda$140/32767196.handle(Unknown Source)
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.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$KeyHandler.process(Scene.java:3965)
at javafx.scene.Scene$KeyHandler.access$1800(Scene.java:3911)
at javafx.scene.Scene.impl_processKeyEvent(Scene.java:2040)
at javafx.scene.Scene$ScenePeerListener.keyEvent(Scene.java:2502)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$KeyEventNotification.run(GlassViewEventHandler.java:197)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$KeyEventNotification.run(GlassViewEventHandler.java:147)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleKeyEvent$349(GlassViewEventHandler.java:228)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$$Lambda$199/17650609.get(Unknown Source)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:404)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleKeyEvent(GlassViewEventHandler.java:227)
at com.sun.glass.ui.View.handleKeyEvent(View.java:546)
at com.sun.glass.ui.View.notifyKey(View.java:956)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$145(WinApplication.java:101)
at com.sun.glass.ui.win.WinApplication$$Lambda$36/17230114.run(Unknown Source)
at java.lang.Thread.run(Thread.java:745)
答案 0 :(得分：1)
我在searchEmployee事件结束时添加了employeeTableView.requestFocus();，并将employeeTableView侦听器中的条件从if(employeeTableView.getSelectionModel().selectedItemProperty() != null)更改为if(employeeTableView.isFocused() == true)
employeeTableView.getSelectionModel().selectedItemProperty().addListener((observableValue, oldValue, newValue) ->
{
//if(employeeTableView.getSelectionModel().selectedItemProperty() != null)
if(employeeTableView.isFocused() == true)
{
empBioKeyLabel.setText(newValue.getBioKeyID());
empNameLabel.setText(newValue.getLname() + ", " + newValue.getFname());
empPositionLabel.setText(newValue.getPosition());
empContactNoLabel.setText(newValue.getContactNo());
}
}