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Populating a table with database data not working

I am trying to load a TableView with data requested from a database, but cannot seem to get them to work.

This is my first attempt to try to populate the database with database query elements, in case my code seems vintage and far from good.

FXML was executed through the JavaFx SceneBuilder.

This is the database query class:

import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.LinkedList; import java.util.List; import javafx.collections.FXCollections; import javafx.collections.ObservableList; public class StudentInfo { static String JDBC_DRIVER = "org.h2.Driver"; static String DB_URL = "jdbc:h2:file:C:/WAKILI/WAKILIdb"; // Database credentials static final String USER = "sa"; static final String PASS = ""; public static Connection conn = null; public List<KIWIDataModel> getAllstudentInfo() { Statement st = null; ResultSet rs; String driver = "org.h2.Driver"; List ll = new LinkedList(); try { Class.forName(driver); conn = DriverManager.getConnection(DB_URL, USER, PASS); st = conn.createStatement(); String recordQuery = ("SELECT id, KIWI FROM KIWI"); rs = st.executeQuery(recordQuery); while (rs.next()) { int Key = rs.getInt(1); ObservableList row = FXCollections.observableArrayList(); for (int i = 1; i <= rs.getMetaData().getColumnCount(); i++) { row.add(rs.getString(i)); System.out.println(row); } KIWIDataModel roww = new KIWIDataModel(); roww.setFirstName(Key); ll.add(row); } } catch (ClassNotFoundException | SQLException ex) { // CATCH SOMETHING } return ll; } }

This is the controller class:

 import DB.KIWI.Try.KIWIDataModel; import DB.KIWI.Try.StudentInfo; import DBQuerry.DynamicTable; import java.net.URL; import java.util.ResourceBundle; import javafx.fxml.FXML; import javafx.fxml.Initializable; import javafx.scene.control.TableColumn; import javafx.scene.control.TableView; import javafx.scene.control.cell.PropertyValueFactory; public class SampleController implements Initializable { @FXML private TableView<KIWIDataModel> Table; @FXML private TableColumn<KIWIDataModel, Integer> colKey; @FXML public void selectKIWITable() { System.out.println("Button Pressed"); colKey.setCellValueFactory(new PropertyValueFactory<KIWIDataModel, Integer>("Key")); Table.getItems().setAll(new StudentInfo().getAllstudentInfo()); } @Override public void initialize(URL url, ResourceBundle rb) { // TODO } }

This is the data model class:

 import javafx.beans.property.SimpleIntegerProperty; public class KIWIDataModel { public SimpleIntegerProperty firstName; public int getFirstName() { return firstName.get(); } public void setFirstName(int fName) { firstName.set(fName); } }

This is an FXML script generated using a JavaFx script:

 <?xml version="1.0" encoding="UTF-8"?> <?import java.lang.*?> <?import java.util.*?> <?import javafx.scene.*?> <?import javafx.scene.control.*?> <?import javafx.scene.layout.*?> <AnchorPane id="AnchorPane" prefHeight="400.0" prefWidth="700.0" xmlns:fx="http://javafx.com/fxml" fx:controller="wakiliproject.SampleController"> <children> <TableView fx:id="Table" prefHeight="400.0" prefWidth="700.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0"> <columns> <TableColumn prefWidth="75.0" text="Column X" fx:id="colKey" /> </columns> </TableView> </children> </AnchorPane>

Update: This is the error I get:

 Button Pressed [1] [1, First KIWI] java.lang.RuntimeException: java.lang.reflect.InvocationTargetException at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1440) at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:69) at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217) at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170) at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35) at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92) at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53) at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33) at javafx.event.Event.fireEvent(Event.java:171) at javafx.scene.Scene$ClickGenerator.postProcess(Scene.java:3117) at javafx.scene.Scene$ClickGenerator.access$8600(Scene.java:3055) at javafx.scene.Scene$MouseHandler.process(Scene.java:3337) at javafx.scene.Scene$MouseHandler.process(Scene.java:3168) at javafx.scene.Scene$MouseHandler.access$1900(Scene.java:3123) at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1563) at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2265) at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:250) at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:173) at java.security.AccessController.doPrivileged(Native Method) at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:292) at com.sun.glass.ui.View.handleMouseEvent(View.java:528) at com.sun.glass.ui.View.notifyMouse(View.java:922) at com.sun.glass.ui.win.WinApplication._runLoop(Native Method) at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:29) at com.sun.glass.ui.win.WinApplication$3$1.run(WinApplication.java:73) at java.lang.Thread.run(Thread.java:724) Caused by: java.lang.reflect.InvocationTargetException at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:75) at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:279) at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1437) ... 30 more Caused by: java.lang.NullPointerException at DB.KIWI.Try.KIWIDataModel.setFirstName(KIWIDataModel.java:14) at DB.KIWI.Try.StudentInfo.getAllstudentInfo(StudentInfo.java:49) at wakiliproject.SampleController.selectKIWITable(SampleController.java:49) ... 40 more
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1 answer

Your null pointer occurs because you never set firstName to anything. Try:

 public IntegerProperty firstName = new SimpleIntegerProperty(0);

Names by numbers represent a strange data model.

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Source: https://habr.com/ru/post/954340/

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