NullPointerException in TableCell.java

Question

I get the error shown below consistently, but I can't quite pinpoint where in my own code the problem originates, as it seems to come from the rendering thread. I seems that it is sort of related to clearing and then repopulating a TableView.
If this is an unknown issue I'll try to put together a simple reproducable example.
SEVERE: javafx.scene.control.Control loadSkinClass Failed to load skin 'com.sun.javafx.scene.control.skin.TableRowSkin' for control TableRow[id=null, styleClass=cell indexed-cell table-row-cell]
java.lang.NullPointerException
     at javafx.scene.control.TableCell.updateItem(TableCell.java:475)
     at javafx.scene.control.TableCell.access$000(TableCell.java:44)
     at javafx.scene.control.TableCell$1.invalidated(TableCell.java:76)
     at com.sun.javafx.binding.ExpressionHelper$SingleInvalidation.fireValueChangedEvent(ExpressionHelper.java:140)
     at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:64)
     at javafx.beans.property.ReadOnlyIntegerWrapper$ReadOnlyPropertyImpl.fireValueChangedEvent(ReadOnlyIntegerWrapper.java:154)
     at javafx.beans.property.ReadOnlyIntegerWrapper.fireValueChangedEvent(ReadOnlyIntegerWrapper.java:120)
     at javafx.beans.property.IntegerPropertyBase.markInvalid(IntegerPropertyBase.java:89)
     at javafx.beans.property.IntegerPropertyBase.set(IntegerPropertyBase.java:122)
     at javafx.scene.control.IndexedCell.updateIndex(IndexedCell.java:91)
     at com.sun.javafx.scene.control.skin.TableRowSkin.updateCells(TableRowSkin.java:224)
     at com.sun.javafx.scene.control.skin.TableRowSkin.<init>(TableRowSkin.java:67)
     at sun.reflect.GeneratedConstructorAccessor5.newInstance(Unknown Source)
     at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
     at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
     at javafx.scene.control.Control.loadSkinClass(Control.java:896)
     at javafx.scene.control.Control.impl_cssSet(Control.java:974)
     at javafx.scene.control.Labeled.impl_cssSet(Labeled.java:604)
     at javafx.scene.Node.impl_cssSet(Node.java:6320)
     at com.sun.javafx.css.StyleHelper.transitionToState(StyleHelper.java:711)
     at javafx.scene.Node.impl_processCSS(Node.java:6194)
     at javafx.scene.Parent.impl_processCSS(Parent.java:965)
     at javafx.scene.control.Control.impl_processCSS(Control.java:1002)
     at com.sun.javafx.scene.control.skin.VirtualFlow.setCellIndex(VirtualFlow.java:1367)
     at com.sun.javafx.scene.control.skin.VirtualFlow.getCell(VirtualFlow.java:1270)
     at com.sun.javafx.scene.control.skin.VirtualFlow.getCellLength(VirtualFlow.java:1293)
     at com.sun.javafx.scene.control.skin.VirtualFlow$3.run(VirtualFlow.java:442)
     at com.sun.javafx.scene.control.skin.VirtualFlow$3.run(VirtualFlow.java:440)
     at com.sun.javafx.scene.control.skin.PositionMapper.computeViewportOffset(PositionMapper.java:122)
     at com.sun.javafx.scene.control.skin.VirtualFlow.layoutChildren(VirtualFlow.java:827)
     at javafx.scene.Parent.layout(Parent.java:900)
     at javafx.scene.Scene.layoutDirtyRoots(Scene.java:451)
     at javafx.scene.Scene.doLayoutPass(Scene.java:424)
     at javafx.scene.Scene.access$2800(Scene.java:132)
     at javafx.scene.Scene$ScenePulseListener.pulse(Scene.java:1750)
     at com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:292)
     at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:398)
     at com.sun.javafx.tk.quantum.QuantumToolkit$10.run(QuantumToolkit.java:330)
     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$2$1.run(WinApplication.java:62)
     at java.lang.Thread.run(Thread.java:662)
SEVERE: javafx.scene.control.Control impl_processCSS The -fx-skin property has not been defined in CSS for TableRow[id=null, styleClass=cell indexed-cell table-row-cell]
SEVERE: javafx.scene.control.Control loadSkinClass Failed to load skin 'com.sun.javafx.scene.control.skin.TableRowSkin' for control TableRow[id=null, styleClass=cell indexed-cell table-row-cell]
java.lang.NullPointerException
     at javafx.scene.control.TableCell.updateItem(TableCell.java:475)
     at javafx.scene.control.TableCell.access$000(TableCell.java:44)
     at javafx.scene.control.TableCell$1.invalidated(TableCell.java:76)
     at com.sun.javafx.binding.ExpressionHelper$SingleInvalidation.fireValueChangedEvent(ExpressionHelper.java:140)
     at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:64)
     at javafx.beans.property.ReadOnlyIntegerWrapper$ReadOnlyPropertyImpl.fireValueChangedEvent(ReadOnlyIntegerWrapper.java:154)
     at javafx.beans.property.ReadOnlyIntegerWrapper.fireValueChangedEvent(ReadOnlyIntegerWrapper.java:120)
     at javafx.beans.property.IntegerPropertyBase.markInvalid(IntegerPropertyBase.java:89)
     at javafx.beans.property.IntegerPropertyBase.set(IntegerPropertyBase.java:122)
     at javafx.scene.control.IndexedCell.updateIndex(IndexedCell.java:91)
     at com.sun.javafx.scene.control.skin.TableRowSkin.updateCells(TableRowSkin.java:224)
     at com.sun.javafx.scene.control.skin.TableRowSkin.<init>(TableRowSkin.java:67)
     at sun.reflect.GeneratedConstructorAccessor5.newInstance(Unknown Source)
     at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
     at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
     at javafx.scene.control.Control.loadSkinClass(Control.java:896)
     at javafx.scene.control.Control.impl_cssSet(Control.java:974)
     at javafx.scene.control.Labeled.impl_cssSet(Labeled.java:604)
     at javafx.scene.Node.impl_cssSet(Node.java:6320)
     at com.sun.javafx.css.StyleHelper.transitionToState(StyleHelper.java:711)
     at javafx.scene.Node.impl_processCSS(Node.java:6194)
     at javafx.scene.Parent.impl_processCSS(Parent.java:965)
     at javafx.scene.control.Control.impl_processCSS(Control.java:1002)
     at com.sun.javafx.scene.control.skin.VirtualFlow.setCellIndex(VirtualFlow.java:1367)
     at com.sun.javafx.scene.control.skin.VirtualFlow.addLeadingCells(VirtualFlow.java:875)
     at com.sun.javafx.scene.control.skin.VirtualFlow.layoutChildren(VirtualFlow.java:831)
     at javafx.scene.Parent.layout(Parent.java:900)
     at javafx.scene.Scene.layoutDirtyRoots(Scene.java:451)
     at javafx.scene.Scene.doLayoutPass(Scene.java:424)
     at javafx.scene.Scene.access$2800(Scene.java:132)
     at javafx.scene.Scene$ScenePulseListener.pulse(Scene.java:1750)
     at com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:292)
     at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:398)
     at com.sun.javafx.tk.quantum.QuantumToolkit$10.run(QuantumToolkit.java:330)
     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$2$1.run(WinApplication.java:62)
     at java.lang.Thread.run(Thread.java:662)

Answer 1

Complete application that consistently produces the error below.
Click "Run", then click on one of the groups, then click "Run" again. Prepare for an avalanche of exceptions.
package tablecellbug;
import com.sun.javafx.collections.ObservableListWrapper;
import java.util.ArrayList;
import java.util.List;
import javafx.application.Application;
import javafx.beans.property.ReadOnlyObjectWrapper;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Orientation;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;
import javafx.util.Callback;
public class TableCellBug extends Application {
    public static void main(String[] args) {
        Application.launch(args);
    class Person {
        int id;
        String name;
        public Person(int id, String name) {
            this.id = id;
            this.name = name;
    class PersonTableView extends TableView<Person> {
        TableColumn<Person, Integer> idColumn = new TableColumn<Person, Integer>();
        TableColumn<Person, String> nameColumn = new TableColumn<Person, String>();
        public PersonTableView() {
            super();
            idColumn.setText("Id");
            idColumn.setCellValueFactory(new Callback<TableColumn.CellDataFeatures<Person, Integer>, ObservableValue<Integer>>() {
                public ObservableValue<Integer> call(TableColumn.CellDataFeatures<Person, Integer> p) {
                    return new ReadOnlyObjectWrapper<Integer>(p.getValue().id);
            nameColumn.setText("Name");
            nameColumn.setCellValueFactory(new Callback<TableColumn.CellDataFeatures<Person, String>, ObservableValue<String>>() {
                public ObservableValue<String> call(TableColumn.CellDataFeatures<Person, String> p) {
                    return new ReadOnlyObjectWrapper<String>(p.getValue().name);
            getColumns().addAll(idColumn, nameColumn);
    final ListView<List<Person>> groupsView = new ListView<List<Person>>();
    final PersonTableView personsView = new PersonTableView();
    @Override
    public void start(Stage stage) {
        BorderPane bp = new BorderPane();
        HBox toolbar = new HBox(10);
        Button go = new Button("Run");
        toolbar.getChildren().add(go);       
        bp.setTop(toolbar);
        SplitPane results = new SplitPane();
        results.setOrientation(Orientation.HORIZONTAL);
        results.getItems().addAll(groupsView, personsView);
        bp.setCenter(results);
        groupsView.setCellFactory(new Callback<ListView<List<Person>>, ListCell<List<Person>>>() {
            public ListCell<List<Person>> call(ListView<List<Person>> p) {
                return new ListCell<List<Person>>() {
                    @Override
                    public void updateItem(List<Person> item, boolean empty) {
                        super.updateItem(item, empty);
                        if (item != null && !item.isEmpty()) setText(item.get(0).name + "'s group");
        groupsView.getSelectionModel().selectedItemProperty().addListener(new ChangeListener<List<Person>>() {
            public void changed(ObservableValue<? extends List<Person>> ov, List<Person> oldGroup, List<Person> newGroup) {
                if (newGroup != null) {
                    personsView.setItems(new ObservableListWrapper<Person>(newGroup));
                else {
                    personsView.setItems(null);
        go.setOnAction(new EventHandler<ActionEvent>() {
            public void handle(ActionEvent t) {
                makeSomeData();
        Scene scene = new Scene(bp, 1024, 768);
        stage.setScene(scene);
        stage.show();
    public void makeSomeData() {
        groupsView.setItems(null);
        System.out.println("Removed old");
        List<List<Person>> groups = new ArrayList<List<Person>>();
        List<Person> group1 = new ArrayList<Person>();
        group1.add(new Person(1, "Tom"));
        group1.add(new Person(2, "Bob"));
        group1.add(new Person(3, "John"));
        group1.add(new Person(4, "Fred"));
        List<Person> group2 = new ArrayList<Person>();
        group2.add(new Person(10, "Ann"));
        group2.add(new Person(20, "Lisa"));
        group2.add(new Person(30, "Mona"));
        group2.add(new Person(40, "Nina"));
        groups.add(group1);
        groups.add(group2);
        groupsView.setItems(new ObservableListWrapper<List<Person>>(groups));
        System.out.println("Added new");
}