Table not updated with new row - javafx

Question

I finally got the content into my table (because I've been mastering that mystery out for ages!). Now I'd like to add new Items to the list AND automatically update the table. I thought an ObservableList would do the trick but there seems to be more to it. Can you provide me with a solution?
Controller class:
package controller;
import java.lang.reflect.Constructor;
import db.ItemLijst;
import db.Klant;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.control.ChoiceBox;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.TextField;
import javafx.scene.control.cell.PropertyValueFactory;
import model.Item;
import model.ItemTypes;
public class SchermController {
#FXML
private TableView<Item> tblItems;
#FXML
private TableView<Klant> tblKlanten;
// #FXML
// private TableView<Uitlening> tblUitleningen;
#FXML
private Button btnItemToevoegen;
#FXML
private Button btnKlantToevoegen;
#FXML
private Button btnRegistreer;
#FXML
private ChoiceBox<ItemTypes> cbTypes;
#FXML
private ChoiceBox<Item> cbItems;
#FXML
private ChoiceBox<Klant> cbKlanten;
#FXML
private TextField tfTitel;
#FXML
private TextField tfVoornaam;
#FXML
private TextField tfAchternaam;
#FXML
private TextField tfStraat;
#FXML
private TextField tfNummer;
#FXML
private TextField tfPostcode;
#FXML
private TextField tfGemeente;
#FXML
private TableColumn<Item, String> tcID;
#FXML
private TableColumn<Item, ItemTypes> tcType;
#FXML
private TableColumn<Item, String> tcTitel;
#FXML
private TableColumn<Item, String> tcUitgeleend;
private ObservableList<Item> items = FXCollections.observableArrayList();
#FXML
private void initialize()
{
/*
* ItemLijst is a static object (or object with all static
methods). the CD, Film and Spel classes automatically add their record to
this class. Literally translated it means ItemList. I thought by making this
an ObservableList, the table would be automatically update its records
depending on a change to this variable (ItemLijst.items<Item>)?
*/
items = FXCollections.observableArrayList(ItemLijst.getItems());
tcID.setCellValueFactory(new PropertyValueFactory<Item, String>("ID"));
tcType.setCellValueFactory(new PropertyValueFactory<Item, ItemTypes>("Type"));
tcTitel.setCellValueFactory(new PropertyValueFactory<Item, String>("Titel"));
tcUitgeleend.setCellValueFactory(new PropertyValueFactory<Item, String>("UitgeleendString"));
tblItems.setItems(items);
// Item types
cbTypes.setItems(FXCollections.observableArrayList(ItemTypes.values()));
btnItemToevoegen.setOnAction(e -> {
try {
itemToevoegen();
} catch (Exception e1) {
System.out.println("Probleem: " + e1.getMessage());
}
});
}
/**
* This is the method which I use to add a new item to the CD, Film or Spel
class (which inherits the Item class).
*/
private void itemToevoegen() throws Exception
{
// Validatie
if (cbTypes.getValue() == null ) {
throw new Exception("Je moet een type kiezen");
} else if (tfTitel.getText().trim().isEmpty()) {
throw new Exception("Je moet een titel ingeven");
}
Class<?> klasse = Class.forName("model." + cbTypes.getValue().toString());
Constructor<?> cons = klasse.getConstructor(String.class);
cons.newInstance(tfTitel.getText());
}
}
FXML:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="438.0" prefWidth="743.0" xmlns="http://javafx.com/javafx/8.0.40" xmlns:fx="http://javafx.com/fxml/1" fx:controller="controller.SchermController">
<children>
<TabPane layoutX="-1.0" prefHeight="438.0" prefWidth="744.0" tabClosingPolicy="UNAVAILABLE">
<tabs>
<Tab closable="false" text="Items">
<content>
<AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="367.0" prefWidth="766.0">
<children>
<TableView fx:id="tblItems" layoutX="14.0" layoutY="14.0" prefHeight="343.0" prefWidth="714.0">
<columns>
<TableColumn fx:id="tcID" prefWidth="303.0" text="Item ID" />
<TableColumn fx:id="tcType" prefWidth="76.0" text="Type" />
<TableColumn fx:id="tcTitel" prefWidth="236.0" text="Titel" />
<TableColumn fx:id="tcUitgeleend" prefWidth="98.0" text="Uitgeleend" />
</columns>
</TableView>
<ChoiceBox fx:id="cbTypes" layoutX="23.0" layoutY="365.0" prefWidth="150.0" />
<TextField fx:id="tfTitel" layoutX="201.0" layoutY="365.0" prefHeight="26.0" prefWidth="352.0" promptText="Titel van item" />
<Button fx:id="btnItemToevoegen" layoutX="592.0" layoutY="365.0" mnemonicParsing="false" prefHeight="26.0" prefWidth="131.0" text="Toevoegen" />
</children>
</AnchorPane>
</content>
</Tab>
<Tab closable="false" text="Klanten">
<content>
<AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="180.0" prefWidth="200.0">
<children>
<TableView fx:id="tblKlanten" layoutX="14.0" layoutY="14.0" prefHeight="343.0" prefWidth="714.0">
<columns>
<TableColumn prefWidth="89.0" text="Klant ID" />
<TableColumn prefWidth="87.0" text="Voornaam" />
<TableColumn prefWidth="105.0" text="Achternaam" />
<TableColumn prefWidth="154.0" text="Straat" />
<TableColumn prefWidth="54.0" text="Nr" />
<TableColumn prefWidth="96.0" text="Postcode" />
<TableColumn prefWidth="128.0" text="Gemeente" />
</columns>
</TableView>
<TextField fx:id="tfVoornaam" layoutX="14.0" layoutY="365.0" prefHeight="26.0" prefWidth="105.0" promptText="Voornaam" />
<TextField fx:id="tfAchternaam" layoutX="125.0" layoutY="365.0" prefHeight="26.0" prefWidth="94.0" promptText="Achternaam" />
<TextField fx:id="tfStraat" layoutX="243.0" layoutY="365.0" prefHeight="26.0" prefWidth="150.0" promptText="Straat" />
<TextField fx:id="tfNummer" layoutX="396.0" layoutY="365.0" prefHeight="26.0" prefWidth="32.0" promptText="Nr" />
<TextField fx:id="tfPostcode" layoutX="431.0" layoutY="365.0" prefHeight="26.0" prefWidth="60.0" promptText="Postcode" />
<TextField fx:id="tfGemeente" layoutX="494.0" layoutY="365.0" prefHeight="26.0" prefWidth="130.0" promptText="Gemeente" />
<Button fx:id="btnKlantToevoegen" layoutX="635.0" layoutY="365.0" mnemonicParsing="false" prefHeight="26.0" prefWidth="93.0" text="Toevoegen" />
</children>
</AnchorPane>
</content>
</Tab>
<Tab closable="false" text="Uitleningen">
<content>
<AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="180.0" prefWidth="200.0">
<children>
<TableView fx:id="tblUitleningen" layoutX="14.0" layoutY="14.0" prefHeight="343.0" prefWidth="714.0">
<columns>
<TableColumn prefWidth="92.0" text="Klant ID" />
<TableColumn prefWidth="324.0" text="Item ID" />
<TableColumn prefWidth="155.0" text="Start Uitleen" />
<TableColumn prefWidth="142.0" text="Eind Uitleen" />
</columns>
</TableView>
<ChoiceBox fx:id="cbItems" layoutX="15.0" layoutY="364.0" prefHeight="26.0" prefWidth="185.0" />
<ChoiceBox fx:id="cbKlanten" layoutX="244.0" layoutY="364.0" prefHeight="26.0" prefWidth="203.0" />
<Button fx:id="btnRegistreer" layoutX="497.0" layoutY="364.0" mnemonicParsing="false" prefHeight="26.0" prefWidth="229.0" text="Registreer Uitlening" />
</children>
</AnchorPane>
</content>
</Tab>
</tabs>
</TabPane>
</children>
</AnchorPane>

Answer 1

Looking at the JavaDoc you will find:
public static <E> ObservableList<E> observableArrayList(Collection<? extends E> col)
Creates a new observable array list and adds a content of collection col to it.
So in fact, you are creating a new ObservableList and adding the initial items to it. The simplest solution would be to have ItemsLijst have an ObservableList, and return it in getItems. Then you should only have to do
tblItems.setItems(ItemsLijst.getItems()); // I corrected the class name