Javafx pie chart made with data from database does not display data - javafx

Question

I am new to Javafx and trying to read and understand tutorials on the internet of how to create charts with data from a Derby database using Scenebuilder.
I have managed to create a bar chart - which works fine.
But I am having some trouble getting the same data shown in a pie chart. Scene builder starts but no pie chart is shown.
What am I missing to have it shown as a pie chart?
Thanks for any help :-)
My code:
public class DocumentController implements Initializable {
#FXML
PieChart piechart;
private Connection connexion;
ArrayList < String > p = new ArrayList < String > ();
ArrayList < Double > c = new ArrayList < > ();
#Override
public void initialize(URL url, ResourceBundle rb) {
loadData();
}
public void loadData() {
String query = "select P, C From PIE "; //ORDER BY P asc
ObservableList < PieChart.Data > piechartdata;
piechartdata = FXCollections.observableArrayList();
try {
connexion = connectDB();
ResultSet rs = connexion.createStatement().executeQuery(query);
while (rs.next()) {
piechartdata.add(new PieChart.Data(rs.getString("P"), rs.getDouble("C")));
p.add(rs.getString("P"));
c.add(rs.getDouble("C"));
}
} catch (Exception e) {
}
}
private Connection connectDB() {
try {
String dbString = "jdbc:derby://localhost:1527/Pie";
String user = "pie";
String password = "pie";
Connection conn = DriverManager.getConnection(dbString, user, password);
System.out.println("Connection Ok");
return conn;
} catch (SQLException ex) {
Logger.getLogger(DocumentController.class.getName()).log(Level.SEVERE, null, ex);
}
return null;
}
}

Answer 1

I think you forgot to set the data of your ObservableList to your pieChart
try something like this:
piechart.setData(piechartdata);
piechart.setVisible(true);