Question

我尝试在SwingWorker类的importData(..)方法中使用TransferHandler（以支持拖放）。我想显示我拖动的文件的导入进度。但是，它不起作用。我不明白问题是什么，或者是什么导致它。

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.
    }       
}

例外：

java.util.concurrent.ExecutionException： java.lang.NullPointerException at java.util.concurrent.FutureTask $ Sync.innerGet（FutureTask.java:222）at 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）在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）在 javax.swing.SwingWorker $ DoSubmitAccumulativeRunnable.actionPerformed（SwingWorker.java:824）在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 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）在java.awt.EventQueue.dispatchEvent（EventQueue.java:611）at java.awt.EventDispatchThread.pumpOneEventForFilters（EventDispatchThread.java:269）在 java.awt.EventDispatchThread.pumpEventsForFilter（EventDispatchThread.java:184）在 java.awt.EventDispatchThread.pumpEventsForHierarchy（EventDispatchThread.java:174）在 java.awt.EventDispatchThread.pumpEvents（EventDispatchThread.java:169）在 java.awt.EventDispatchThread.pumpEvents（EventDispatchThread.java:161）在java.awt.EventDispatchThread.run（EventDispatchThread.java:122）引起：java.lang.NullPointerException at sun.awt.dnd.SunDropTargetContextPeer.getTransferDataFlavors（SunDropTargetContextPeer.java:176）在 sun.awt.datatransfer.TransferableProxy.getTransferDataFlavors（TransferableProxy.java:48）在 java.awt.dnd.DropTargetContext中$ TransferableProxy.getTransferDataFlavors（DropTargetContext.java:327）

Answer 1

您没有对SwingWorker的引用以及从doInBackground()
请阅读@trashgod to my question about similair issue
在SSCCE发布后可以更快获得更好的帮助，因为可能还有FileIO的另一个问题（您可以生成文件飞到\ temp），
I found two - three another issues，也许是Bug，也许不是，paintImmediately()已解决

SwingWorker中抛出异常

1 个答案: