Getting NullPointerException in initialize method of Controller JavaFX

Question

Following is the NullPointerException I'm getting in initialize method of controller class:

`Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1774)
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1657)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
    at javafx.event.Event.fireEvent(Event.java:198)
    at javafx.scene.Node.fireEvent(Node.java:8411)
    at javafx.scene.control.Button.fire(Button.java:185)
    at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
    at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.event.Event.fireEvent(Event.java:198)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
    at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:352)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:275)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:388)
    at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:387)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
    at com.sun.glass.ui.View.notifyMouse(View.java:937)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
    at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
    at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1769)
    ... 48 more
Caused by: javafx.fxml.LoadException: 
file:/C:/Users/W7/Documents/NetBeansProjects/PivotNSE/dist/run2050028213/PivotNSE.jar!/pivotnse/popupFXML.fxml

    at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2601)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2579)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3214)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)
    at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)
    at pivotnse.PivotFXController.handleLoadButton(PivotFXController.java:173)
    ... 58 more
Caused by: java.lang.NullPointerException
    at pivotnse.PivotFXController.initialize(PivotFXController.java:294)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
    ... 66 more`

What I am trying to do is, when myLoadButton is clicked, a new window pops up and shows in the Label of new window all the Symbols that are currently getting "downloaded"! (kind of like "real time update" to user). Just so the user knows, what's happening. Following is the Code:

 public class PivotFXController implements Initializable {

        final ObservableList<GetPivots> data = FXCollections.observableArrayList();

        @FXML
        private TableView<GetPivots> pivotTable;

        @FXML
        private TableColumn<GetPivots, String> symbolColumn;
        @FXML
        private TableColumn<GetPivots, String> pivotColumn;
        @FXML
        private TableColumn<GetPivots, String> r1Column;
        @FXML
        private TableColumn<GetPivots, String> r2Column;

        @FXML
        private TableColumn<GetPivots, String> r3Column;

        @FXML
        private TableColumn<GetPivots, String> s1Column;
        @FXML
        private TableColumn<GetPivots, String> s2Column;
        @FXML
        private TableColumn<GetPivots, String> s3Column;
        @FXML
        private Label statusLabel;
        @FXML
        private Button myLoadButton;
        @FXML
        private Button doneButton;

        @FXML
        private TextField symbolField;

        private String SYMBOLS_FILE = "SYMBOLS.txt";

        private static List<String> symbolList = new ArrayList<String>();


        private boolean handleSymbol(String symbol) {
            System.out.println(symbol + " is the input");
            // statusLabel.setText("Downloading... " + symbol);
            FetchDataNSE fdn = new FetchDataNSE();

            if (fdn.getDataNSE(symbol).size() > 0) {
                CalculatePivot cp = new CalculatePivot(fdn.getDataNSE(symbol));
                GetPivots gp = new GetPivots(cp);
                data.add(gp);
                //   statusLabel.setText(symbol + " " + "Downloaded!");
                return true;
            }
            return false;
        }



        @FXML
        private void handleLoadButton(ActionEvent event) throws IOException {
            Stage stage;
            Parent root;
            if (event.getSource() == myLoadButton) {
                //get reference to the button's stage         
                stage = (Stage) myLoadButton.getScene().getWindow();
                //load up OTHER FXML document
                root = FXMLLoader.load(getClass().getResource("popupFXML.fxml"));// <-- ****this line is causing problem**** I am getting NULLPOINTEREXCEPTION from 1st line in `initialize` method WHY?
                stage.setScene(new Scene(root));
                stage.setTitle("DOWNLOADING STATUS");
                stage.initModality(Modality.APPLICATION_MODAL);
                stage.showAndWait();
                loadSymbols();

            } else {
                stage = (Stage) doneButton.getScene().getWindow();
                root = FXMLLoader.load(getClass().getResource("pivotFXGUI.fxml"));
                Scene scene = new Scene(root);
                stage.setScene(scene);
                stage.show();
            }


        }

        private void loadSymbols() {
            data.clear();
            symbolList.clear();

            BufferedReader br = null;

            try {

                String sCurrentLine;

                br = new BufferedReader(new FileReader(SYMBOLS_FILE));

                while ((sCurrentLine = br.readLine()) != null) {
                    symbolList.add(sCurrentLine.trim());
                }

            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    if (br != null) {
                        br.close();
                    }
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }

            for (String sym : symbolList) {
                statusLabel.setText("Downloading... " + sym);
                handleSymbol(sym);
            }

            statusLabel.setText("LOADING SYMBOLS DONE!");
        }




        @Override
        public void initialize(URL url, ResourceBundle rb) {
    // 1st line below gives NullPointerException! why does that happen?
            symbolColumn.setCellValueFactory(new PropertyValueFactory<>("symbolProperty"));
            pivotColumn.setCellValueFactory(new PropertyValueFactory<>("pivotProperty"));
            r1Column.setCellValueFactory(new PropertyValueFactory<>("r1Property"));
            r2Column.setCellValueFactory(new PropertyValueFactory<>("r2Property"));
            r3Column.setCellValueFactory(new PropertyValueFactory<>("r3Property"));
            s1Column.setCellValueFactory(new PropertyValueFactory<>("s1Property"));
            s2Column.setCellValueFactory(new PropertyValueFactory<>("s2Property"));
            s3Column.setCellValueFactory(new PropertyValueFactory<>("s3Property"));
            pivotTable.setItems(data);

            // myLoadButton.fire();
            //  pivotTable.getColumns().addAll(symbolColumn,s3Column, s2Column,s1Column, pivotColumn, r1Column, r2Column, r3Column  );

        }


    }
`

Why is the 1st line in the "initialize" method throwing NullPointerException!? What am I doing incorrectly in handleLoadButton(..) method and initialize(..) method? When I remove everything from initialize method program opens up new window when I click myLoadButton, but then NullPointerException occurs when loadSymbols() method is called...

ALSO::: at pivotnse.PivotFXController.handleLoadButton(PivotFXController.java:173) ... 58 more Caused by: java.lang.NullPointerException at pivotnse.PivotFXController.initialize(PivotFXController.java:294) line 173 is following::: root = FXMLLoader.load(getClass().getResource("popupFXML.fxml")); and line 294 is the 1st line in initialize() method.

Please boil down your code to the minimum which shows the problem. Nobobody want to read such big copy/paste desert. — Heri
– Heri, Commented Jul 3, 2016 at 17:24
I'm wondering why loading popupFXML.fxml would fire PivotFXController.initialize() in the first place? You'd expect it to call PopupFXML.initialize(), no? Got a fx:controller="<controller>" attribute in popupFXML.fxml and what does it say? — Arjan
– Arjan, Commented Jul 3, 2016 at 18:01
fx:controller="pivotnse.PivotFXController" <-- this is in popupFXML.fxml, PivotFXController is the main controller which popupFXML.fxml also uses — Bigshot
– Bigshot, Commented Jul 3, 2016 at 18:04

mipa · Accepted Answer · 2016-07-03 17:45:23Z

1

Probably "symbolColumn" has not been initialized. Maybe you have forgotten or misspelled the fx:id in your fxml-file.

answered Jul 3, 2016 at 17:45

mipa

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1 Comment

Bigshot Over a year ago

Problem occurs only when myLoadButton is clicked! Everything else works fine!

Arjan · Accepted Answer · 2016-07-03 18:15:09Z

1

The relation between fxml documents and the controllers is 1:1 by design. In other words, each fxml document should have its own controller.

Right now you're trying to load popupFXML.fxml with pivotnse.PivotFXController as controller. So your initialize() executes symbolColumn.setCellValueFactory() while symbolColumn wasn't injected, because popupFXML.fxml doesn't have a symbolColumn. Result: NPE.

You should make a seperate controller class for popupFXML.fxml and reference it in your fxml like fx:controller="pivotnse.PopupFXMLController"

answered Jul 3, 2016 at 18:15

Arjan

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3 Comments

Bigshot Over a year ago

2 FXML 1 Controller @Arjan Here author uses same controller for 2 fxml files, see the first 5th point from bottom of the page...

Arjan Over a year ago

@Bigshot Yeah, that author coincidentally has 2 fxml files which are quite simple, so in his case it can work. You have a TableView in one fxml file, you're setting the cellValueFactory of its columns in the controller's initialize method. But you don't have the TableView in the other fxml file, so setting the cellValueFactory results in a NPE. Btw, The 1:1 association between an FXML document and its controller is by design, those are the words of JavaFX' designer Greg Brown... Feel free to ignore them and follow some other pattern, of course :)

James_D Over a year ago

That tutorial is absolute nonsense and is full of errors. Don't believe everything you read on the Internet. Each FXML file should have its own controller class.

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