我正在创建一个应用程序作为我的家庭作业，它接收客户信息并使用derby数据库和javafx对其进行注册。注册后，新客户将出现在表格视图中。我一直在尝试向tableview添加行，但是java.lang.reflect.InvocationTargetException不断弹出，我不知道发生了什么。我想从我的derby数据库中检索数据，并将其显示在应用程序的tableview中。打开应用程序时，有一个添加新客户的选项。单击添加新客户的选项时，将弹出一个新窗口，询问新客户的信息。我为新的客户输入窗口创建了一个单独的FXML文件，并为其创建了一个单独的控制器（此处均未显示）。在客户输入窗口中输入所有必需的信息之后，单击“提交”按钮，输入的信息将被插入derby数据库，然后NewCustomerEntryController类将在“ RetailSystemController”类中调用“ handleNewSubmit”方法（如图下面）。请在下面查看我的代码以及弹出的异常。
这是重写javafx的start方法的主类，并且我已经在此类中为derby设置了驱动程序和URL连接
package retailsystem;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.sql.DatabaseMetaData;
public class main extends Application {
private static Connection conn;
@Override
public void start(Stage primaryStage) throws Exception {
Parent root = FXMLLoader.load(getClass().getResource("retailsystem.fxml"));
primaryStage.setTitle("Retail System Management");
primaryStage.setScene(new Scene(root, 600, 400));
setUpDB();
primaryStage.show();
}
private void setUpDB() throws Exception {
String driver = "org.apache.derby.jdbc.EmbeddedDriver";
String dbName = "RetailSystemDB";
String connectionURL = "jdbc:derby:" + dbName + ";create=true";
String createCustomerString = "CREATE TABLE Customer (FirstName VARCHAR (50) NOT "
+ "NULL, LastName VARCHAR(50) NOT NULL, StreetAddress VARCHAR(50) "
+ "NOT NULL, City VARCHAR(20) NOT NULL, State VARCHAR(12) NOT NULL, "
+ "Zipcode VARCHAR(5), Gender VARCHAR(6))";
Class.forName(driver);
conn = DriverManager.getConnection(connectionURL);
Statement stmt = conn.createStatement();
DatabaseMetaData dbm = conn.getMetaData();
ResultSet checkCustomer = dbm.getTables(null, null, "CUSTOMER", null);
if (!checkCustomer.next()) {
stmt.executeUpdate(createCustomerString);
}
stmt.close();
}
public static Connection getConn() {
return conn;
}
public static void main(String[] args) {
launch(args);
}
}
下面的代码是新客户输入窗口的控制器：
package retailsystem;
import java.io.File;
import java.net.URL;
import java.util.ResourceBundle;
import java.util.Scanner;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.ComboBox;
import javafx.scene.control.RadioButton;
import javafx.scene.control.TextField;
import javafx.scene.control.ToggleGroup;
import javafx.stage.Stage;
import java.sql.Connection;
import java.sql.PreparedStatement;
import javafx.scene.control.TableView;
public class CustomerInformationController implements Initializable {
@FXML
private TextField fEntry;
@FXML
private TextField lEntry;
@FXML
private TextField aEntry;
@FXML
private TextField cEntry;
@FXML
private ComboBox<String> sEntry;
@FXML
private RadioButton male;
@FXML
private RadioButton female;
@FXML
private TextField zEntry;
@FXML
private Button submitBTN;
@FXML
private Button cancelBtn;
private static person customer;
ToggleGroup group = new ToggleGroup();
/**
* Initializes the controller class.
*/
@Override
public void initialize(URL url, ResourceBundle rb) {
// TODO
String[] stateList = getStateList();
for (int i = 0; i < stateList.length; i++) {
sEntry.getItems().add(stateList[i]);
}
sEntry.setValue(stateList[0]);
male.setToggleGroup(group);
female.setToggleGroup(group);
}
@FXML
private void handleSubmit(ActionEvent event) throws Exception {
RadioButton selectedBtn = (RadioButton) group.getSelectedToggle();
customer = new person(fEntry.getText(), lEntry.getText(),
aEntry.getText(), cEntry.getText(), sEntry.getValue(), zEntry.getText(),
selectedBtn.getText());
Connection conn = main.getConn();
PreparedStatement psInsert = conn.prepareStatement("INSERT INTO CUSTOMER "
+ "(FirstName, LastName, StreetAddress, City, State, Zipcode, "
+ "Gender) VALUES(?,?,?,?,?,?,?)");
psInsert.setString(1, customer.getFirstName());
psInsert.setString(2, customer.getLastName());
psInsert.setString(3, customer.getAddress());
psInsert.setString(4, customer.getCity());
psInsert.setString(5, customer.getState());
psInsert.setString(6, customer.getZipcode());
psInsert.setString(7, customer.getGender());
psInsert.executeUpdate();
RetailSystemController retailcontroller = new RetailSystemController();
retailcontroller.handleNewSubmit();
psInsert.close();
}
}
下面的代码是我的fxml文件
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Menu?>
<?import javafx.scene.control.MenuBar?>
<?import javafx.scene.control.MenuItem?>
<?import javafx.scene.control.TableColumn?>
<?import javafx.scene.control.TableView?>
<?import javafx.scene.layout.BorderPane?>
<BorderPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="retailsystem.RetailSystemController">
<center>
<TableView fx:id="tView" prefHeight="200.0" prefWidth="200.0" BorderPane.alignment="CENTER">
<columns>
<TableColumn fx:id="fName" prefWidth="90.0" text="First Name" />
<TableColumn fx:id="lName" prefWidth="90.0" text="Last Name" />
<TableColumn fx:id="address" prefWidth="147.0" text="Street Address" />
<TableColumn fx:id="city" prefWidth="87.0" text="City" />
<TableColumn fx:id="state" prefWidth="64.0" text="State" />
<TableColumn fx:id="zip" prefWidth="62.0" text="Zip Code" />
<TableColumn fx:id="gender" prefWidth="70.0" text="Gender" />
</columns>
</TableView>
</center>
<top>
<MenuBar BorderPane.alignment="CENTER">
<menus>
<Menu mnemonicParsing="false" text="Customer">
<items>
<MenuItem mnemonicParsing="false" onAction="#handleCustomerAddNew" text="Add New" />
<MenuItem mnemonicParsing="false" onAction="#handleCustomerListAll" text="List All" />
</items>
</Menu>
<Menu mnemonicParsing="false" text="Employee">
<items>
<MenuItem mnemonicParsing="false" onAction="#handleEmployeeAddNew" text="Add New " />
<MenuItem mnemonicParsing="false" onAction="#handleEmployeeListAll" text="List All" />
</items>
</Menu>
<Menu mnemonicParsing="false" text="Merchandise">
<items>
<MenuItem mnemonicParsing="false" onAction="#handleMerchandiseAddNew" text="Add New" />
<MenuItem mnemonicParsing="false" onAction="#handleMerchandiseListAll" text="List All" />
</items>
</Menu>
</menus>
</MenuBar>
</top>
</BorderPane>
下面的代码是上述fxml文件的控制器类，该类中有很多处理程序，但是由于我尚未编写太多代码，因此我现在仅关注“ handleCustomerAddnew”和“ handleNewSubmit”。其他。 问题发生在此类的handleNewSubmit方法中：
package retailsystem;
import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.stage.Stage;
import javafx.stage.Window;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
public class RetailSystemController implements Initializable {
@FXML
private TableColumn fName;
@FXML
private TableColumn lName;
@FXML
private TableColumn address;
@FXML
private TableColumn city;
@FXML
private TableColumn state;
@FXML
private TableColumn zip;
@FXML
private TableColumn gender;
@FXML
private TableView<person> tView;
public void initialize(URL url, ResourceBundle rb) {
//ToDo
fName.setCellValueFactory(new PropertyValueFactory<person, String>("firstName"));
lName.setCellValueFactory(new PropertyValueFactory<person, String>("lastName"));
address.setCellValueFactory(new PropertyValueFactory<person, String>("address"));
city.setCellValueFactory(new PropertyValueFactory<person, String>("city"));
state.setCellValueFactory(new PropertyValueFactory<person, String>("state"));
zip.setCellValueFactory(new PropertyValueFactory<person, String>("Zipcode"));
gender.setCellValueFactory(new PropertyValueFactory<person, String>("gender"));
}
@FXML
private void handleCustomerAddNew(ActionEvent event) {
Parent root;
try {
root = FXMLLoader.load(getClass().getResource("customerinformation.fxml"));
Stage stage = new Stage();
stage.setTitle("Customer Information");
stage.setScene(new Scene(root, 400, 340));
stage.show();
} catch (IOException e) {
e.printStackTrace();
}
}
public void handleNewSubmit() {
System.out.println("beginning of handleNewSubmit");
ArrayList<person> registeredPersons=new ArrayList<person>();
Connection conn = main.getConn();
String query = "SELECT * FROM CUSTOMER";
try{
PreparedStatement stmt = conn.prepareStatement(query);
ResultSet resultset = stmt.executeQuery();
while(resultset.next()){
System.out.println(resultset.getString("FirstName")+" "+resultset.getString("LastName"));
registeredPersons.add(new person(resultset.getString("FirstName"),resultset.getString("LastName"), resultset.getString("StreetAddress"),
resultset.getString("City"),resultset.getString("State"),resultset.getString("Zipcode"),resultset.getString("Gender")));
}}
catch (Exception e){
e.printStackTrace();
}
ObservableList<person> items = FXCollections.observableArrayList(registeredPersons);
System.out.println("before adding to tView");
tView.setItems(items);
System.out.println("after adding to tView");
}
}
错误：
Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at javafx.fxml/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1787)
at javafx.fxml/javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1670)
at javafx.base/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:234)
at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at javafx.base/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at javafx.base/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at javafx.base/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
at javafx.base/javafx.event.Event.fireEvent(Event.java:198)
at javafx.graphics/javafx.scene.Node.fireEvent(Node.java:8885)
at javafx.controls/javafx.scene.control.Button.fire(Button.java:203)
at javafx.controls/com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:206)
at javafx.controls/com.sun.javafx.scene.control.inputmap.InputMap.handle(InputMap.java:274)
at javafx.base/com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:247)
at javafx.base/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:234)
at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at javafx.base/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at javafx.base/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at javafx.base/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.base/javafx.event.Event.fireEvent(Event.java:198)
at javafx.graphics/javafx.scene.Scene$MouseHandler.process(Scene.java:3890)
at javafx.graphics/javafx.scene.Scene.processMouseEvent(Scene.java:1885)
at javafx.graphics/javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2618)
at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:409)
at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:299)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:447)
at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:412)
at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:446)
at javafx.graphics/com.sun.glass.ui.View.handleMouseEvent(View.java:556)
at javafx.graphics/com.sun.glass.ui.View.notifyMouse(View.java:942)
at javafx.graphics/com.sun.glass.ui.mac.MacView.notifyMouse(MacView.java:127)
Caused by: java.lang.reflect.InvocationTargetException
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at com.sun.javafx.reflect.Trampoline.invoke(MethodUtil.java:76)
at jdk.internal.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at javafx.base/com.sun.javafx.reflect.MethodUtil.invoke(MethodUtil.java:273)
at javafx.fxml/com.sun.javafx.fxml.MethodHelper.invoke(MethodHelper.java:83)
at javafx.fxml/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1782)
... 44 more
Caused by: java.lang.NullPointerException
at retailsystem.RetailSystemController.handleNewSubmit(RetailSystemController.java:127)
at retailsystem.CustomerInformationController.handleSubmit(CustomerInformationController.java:102)
... 55 more
NullPointerException正在发生
tView.setItems(items);
tView是您的FXML文件中定义的TableView；加载FXML文件时，它将在控制器中初始化。调用handleNewSubmit()时为null的原因是您不是在控制器上调用该方法，而是在您创建的任意对象（与控制器相同的类）上调用该方法：
private void handleSubmit(ActionEvent event) throws Exception {
// ...
RetailSystemController retailcontroller = new RetailSystemController();
retailcontroller.handleNewSubmit();
// ...
}
解决此问题的最佳方法就是，在显示CustomerInformationController文件时，将表格的项目列表传递给customerinformation.fxml。这样CustomerInformationController可以直接更新表数据。现在，当您添加新项时，您正尝试再次从数据库中加载所有数据：这似乎非常不必要；如果数据库更新成功，则只需将新项添加到列表中。
因此您可以这样做：
public class RetailSystemController implements Initializable {
// ...
@FXML
private void handleCustomerAddNew(ActionEvent event) {
Parent root;
try {
FXMLLoader loader = new FXMLLoader(getClass().getResource("customerinformation.fxml"));
root = loader.load();
CustomerInformationController ciController = loader.getController();
ciController.setDataList(tbl.getItems());
Stage stage = new Stage();
stage.setTitle("Customer Information");
stage.setScene(new Scene(root, 400, 340));
stage.show();
} catch (IOException e) {
e.printStackTrace();
}
}
public void handleNewSubmit() {
// you probably don't need this method any more
}
// ...
}
然后：
public class CustomerInformationController implements Initializable {
// ...
private ObservableList<person> dataList ;
public void setDataList(ObservableList<person> dataList) {
this.dataList = dataList();
}
// ...
@FXML
private void handleSubmit(ActionEvent event) throws Exception {
RadioButton selectedBtn = (RadioButton) group.getSelectedToggle();
customer = new person(fEntry.getText(), lEntry.getText(),
aEntry.getText(), cEntry.getText(), sEntry.getValue(), zEntry.getText(),
selectedBtn.getText());
Connection conn = main.getConn();
PreparedStatement psInsert = conn.prepareStatement("INSERT INTO CUSTOMER "
+ "(FirstName, LastName, StreetAddress, City, State, Zipcode, "
+ "Gender) VALUES(?,?,?,?,?,?,?)");
psInsert.setString(1, customer.getFirstName());
psInsert.setString(2, customer.getLastName());
psInsert.setString(3, customer.getAddress());
psInsert.setString(4, customer.getCity());
psInsert.setString(5, customer.getState());
psInsert.setString(6, customer.getZipcode());
psInsert.setString(7, customer.getGender());
psInsert.executeUpdate();
// RetailSystemController retailcontroller = new RetailSystemController();
// retailcontroller.handleNewSubmit();
psInsert.close();
dataList.add(customer) ;
}
// ...
}
显然，在真实的应用程序中，您将数据库代码移到一个单独的类，并适当地处理异常，等等。
如果确实确实需要在添加新条目之后再次从数据库中重新加载整个列表，则可以使用handleSubmit()方法执行此操作，而只需使用dataList.setAll(...)替换现有项，等等。但是同样，由于您知道您刚刚对数据库进行了哪些更改，因此您可以对表的后备列表进行相同的更改。