Exception thrown in SwingWorker

Question

I am trying to use a SwingWorker in the importData(..) method from the TransferHandler class (to support drag and drop). I want to show the import progress of the files that I dragged. However, it does not work. I don't understand what the problem is, or what causing it.

private class FileImportTransferHandler extends TransferHandler {

    @Override
    public boolean importData(JComponent comp, final Transferable t) {

        SwingWorker<Void, String> worker = new SwingWorker<Void, String>() {

            @Override
            protected Void doInBackground() throws Exception {
                //When commenting this code it and everything else it doesn't
                DataFlavor[] flavors = t.getTransferDataFlavors(); //<---- throws exception 
                //..more code that doesn't run.
            }

            @Override
            protected void done() {
                super.done();

                try {
                    get();
                } catch (InterruptedException ex) {
                    Logger.getLogger(ImportBeanController.class.getName()).log(Level.SEVERE, null, ex);
                } catch (ExecutionException ex) {
                    Logger.getLogger(ImportBeanController.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
        }
       //Starting worker etc here.
    }       
}

Exception:

java.util.concurrent.ExecutionException: java.lang.NullPointerException at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:222) at java.util.concurrent.FutureTask.get(FutureTask.java:83) at javax.swing.SwingWorker.get(SwingWorker.java:582) at com.jatech.app.controllers$ImportBeanController$1.done(ImportBeanController.java:158) at javax.swing.SwingWorker$5.run(SwingWorker.java:717) at javax.swing.SwingWorker$DoSubmitAccumulativeRunnable.run(SwingWorker.java:814) at sun.swing.AccumulativeRunnable.run(AccumulativeRunnable.java:95) at javax.swing.SwingWorker$DoSubmitAccumulativeRunnable.actionPerformed(SwingWorker.java:824) at javax.swing.Timer.fireActionPerformed(Timer.java:291) at javax.swing.Timer$DoPostEvent.run(Timer.java:221) at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:641) at java.awt.EventQueue.access$000(EventQueue.java:84) at java.awt.EventQueue$1.run(EventQueue.java:602) at java.awt.EventQueue$1.run(EventQueue.java:600) at java.security.AccessController.doPrivileged(Native Method) at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87) at java.awt.EventQueue.dispatchEvent(EventQueue.java:611) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122) Caused by: java.lang.NullPointerException at sun.awt.dnd.SunDropTargetContextPeer.getTransferDataFlavors(SunDropTargetContextPeer.java:176) at sun.awt.datatransfer.TransferableProxy.getTransferDataFlavors(TransferableProxy.java:48) at java.awt.dnd.DropTargetContext$TransferableProxy.getTransferDataFlavors(DropTargetContext.java:327)

which exception? Anyway, more context needed - please show an SSCCE — kleopatra, Oct 17 '12 at 13:37
@Dude your code in doInBackground threw a NullPointerException. Without that exception and the corresponding code, nobody will be able to help you more. Looks like you are still accessing AWT-DND info in your doInBackground--> do that before creating your SwingWorker and only perform the import operation within the SwingWorker#doInBackground() — Guillaume Polet, Oct 17 '12 at 13:46

score 3 · Answer 1 · edited May 23 '17 at 12:33

3

you don't have got refference to the SwingWorker and whatever is/are invoked from doInBackground()
please read answer by @trashgod to my question about similair issue
for better help sooner post an SSCCE, because maybe there are another issue with FileIO (you can to generate File on fly to \temp),
I found two - three another issues, maybe Bug, maybe not, solved by paintImmediately()

edited May 23 '17 at 12:33

Community

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answered Oct 17 '12 at 13:49

mKorbel

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Exception thrown in SwingWorker

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