I wrote code for a TableView that will allow rows to drag and drop. Works great as a standalone JavaFX application. However, it doesn't work in an embedded JFXPanel for work in a Swing app. I want to integrate it with my Swing app, so I can't use it as a standalone.

The error is in the JavaFX code itself, which isn't giving me a whole lot to go on.


java.lang.AssertionError
at javafx.embed.swing.SwingDnD.startDrag(SwingDnD.java:261)
at javafx.embed.swing.SwingDnD.access$1000(SwingDnD.java:73)
at javafx.embed.swing.SwingDnD$4$1.run(SwingDnD.java:249)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:744)
at java.awt.EventQueue.access$400(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:697)
at java.awt.EventQueue$3.run(EventQueue.java:691)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:714)




Here is my code that creates the handler in a customized TableView class



private EventHandler<MouseEvent> createDragDetectedHandler(
    final TableCell<ReportSelectedItem, String> cell) {
    return new EventHandler<MouseEvent>() {
        @Override
        public void handle(MouseEvent event) {
            try {

                Dragboard db = cell.startDragAndDrop(TransferMode.MOVE);
                ClipboardContent content = new ClipboardContent();
                content.putString(String.valueOf(cell.getIndex()));
                WritableImage snapshot = cell.getTableRow().snapshot(new SnapshotParameters(), null);
                db.setDragView(snapshot);
                db.setContent(content);
            } catch (AssertionError ex) {
                ex.printStackTrace();
            }
        }
    };
}


The exception is thrown from this line: Dragboard db = cell.startDragAndDrop(TransferMode.MOVE);

So, I noticed that it's calling SwingDnD in my embedded instance, but GlassScene in the stand alone. So it's using different code for the Drag and Drop functionality.