WebView NullPointerException using JavaFX

Question

Recently adding a WebView pane to my JavaFX Application. When resizing my program I get this error and the program freezes.

java.lang.NullPointerException
    at com.sun.javafx.webkit.prism.WCPageBackBufferImpl.validate(WCPageBackBufferImpl.java:97)
    at com.sun.webkit.WebPage.paint(WebPage.java:644)
    at com.sun.javafx.sg.prism.NGWebView.renderContent(NGWebView.java:95)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2067)
    at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1959)
    at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
    at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:576)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2067)
    at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1959)
    at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
    at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:576)
    at com.sun.javafx.sg.prism.NGNode.renderForClip(NGNode.java:2308)
    at com.sun.javafx.sg.prism.NGNode.renderRectClip(NGNode.java:2202)
    at com.sun.javafx.sg.prism.NGNode.renderClip(NGNode.java:2228)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2061)
    at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1959)
    at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
    at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:576)
    at com.sun.javafx.sg.prism.NGNode.renderForClip(NGNode.java:2308)
    at com.sun.javafx.sg.prism.NGNode.renderRectClip(NGNode.java:2202)
    at com.sun.javafx.sg.prism.NGNode.renderClip(NGNode.java:2228)
    at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2061)
    at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1959)
    at com.sun.javafx.tk.quantum.ViewPainter.doPaint(ViewPainter.java:474)
    at com.sun.javafx.tk.quantum.ViewPainter.paintImpl(ViewPainter.java:327)
    at com.sun.javafx.tk.quantum.PresentingPainter.run(PresentingPainter.java:91)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
    at com.sun.javafx.tk.RenderJob.run(RenderJob.java:58)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at com.sun.javafx.tk.quantum.QuantumRenderer$PipelineRunnable.run(QuantumRenderer.java:125)
    at java.lang.Thread.run(Thread.java:745)

The website that the webview goes to is

http://www.abendigo.org/gui/

Can someone tell me what causes this issue?

Edit: Not sure why this is needed, but here is the code as requested:

public class Controller implements Initializable {

    @FXML
    public WebView webView;

    @Override
    public void initialize(URL location, ResourceBundle resources) {
        webView.getEngine().load("http://abendigo.org/gui/");
    }

}

Video of bug reproduction: https://youtu.be/6CLPt45AbW0

Can you post the code? The error message can only be so helpful without code. — Rob Rushton
– Rob Rushton, Commented Aug 10, 2015 at 1:47
I cannot reproduce this. What JDK version and platform are you using? Can you post your code in the form of an MCVE — James_D
– James_D, Commented Aug 10, 2015 at 2:07
I've uploaded a video of me reproducing the bug myself. Also happens on my partners computer. — Jonathan Beaudoin
– Jonathan Beaudoin, Commented Aug 10, 2015 at 2:14
This exception reproduces on OS X 10.9.5, Java 8u60, only after continually manually resizing the window for a minute or two. Related bug report link. — jewelsea
– jewelsea, Commented Oct 7, 2015 at 19:24

Daniel · Accepted Answer · 2018-04-20 07:13:40Z

4

I was faced with the same bug. It was quite difficult to find the reason. At last, I found : webView layout throw a nullPointerExpection when width or height is too large, ie over 8500 pixel.

And the good bypass was too limit the maxWidth/maxHeight of the webView to scene size :

 webView.sceneProperty().addListener(new ChangeListener<Scene>() {

        @Override
        public void changed(ObservableValue<? extends Scene> observable, Scene oldValue, Scene scene) {
            if (scene != null) {
                webView.setMaxSize(getScene().getWidth(), getScene().getHeight());
                webView.maxWidthProperty().bind(getScene().widthProperty());
                webView.maxHeightProperty().bind(getScene().heightProperty());
            } else {
                webView.maxWidthProperty().unbind();
                webView.maxHeightProperty().unbind();
            }
        }
    });

edited Apr 20, 2018 at 7:13

answered Oct 5, 2015 at 20:42

Daniel

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2 Comments

Weijing Jay Lin Over a year ago

Where should I apply the code?! Also for canvas, my webview actually limited to the scale, and it still have the issue.

Daniel Over a year ago

On the webview itself (I updated my answer so that it is more readable). For canvas, I let you try.

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