dragging and dropping from one JavaFX Application to another - drag-and-drop

Question

I am trying to move an element from one JavaFX application to another via drag-and-drop, as far as I understand this shouldnt be a problem.
So I have an object of a class and drag it from one application to the other and then have its contents printed to the console. It's mostly looking good, I can get the drop to "accepted" or "not accepted" by playing around with transfer modes, which shows me that the mechanism itself seems to be working.
But when I drop the object on the other application a bunch of, what I believe to be mostly chinese, letters are printed to the console. This is apparently some encoding problem, but I can't really figure out what's happening, aside from the fact that both applications mainly use the same codebase, the "chinese" letters are quite numerous. The object's toString merely prints one and a half line in latin characters, but upon dropping there are several paragraphs of "chinese" letters printed.
Can anyone tell me what's happening here? Is it just a simple encoding f-up? Does the OS (Win7 btw) maybe interfer here? Have I uncovered long lost ancient chinese wisdom?
The code itself is rather simple, here is the code from the "sender"
setOnDragDetected(event ->
{
Dragboard db = startDragAndDrop(TransferMode.ANY);
ClipboardContent clipboardContent = new ClipboardContent();
clipboardContent.put(DataFormat.PLAIN_TEXT, treeElement.getEntities());
db.setContent(clipboardContent);
System.out.println(db.getContent(DataFormat.PLAIN_TEXT));
event.consume();
});
and here from the "receiver"
setOnDragDropped(event ->
{
Dragboard db = event.getDragboard();
if (db.hasContent(DataFormat.PLAIN_TEXT))
{
System.out.println(db.getContent(DataFormat.PLAIN_TEXT));
System.out.println("Accept Drop");
}
event.consume();
});
I just don't really see anything that would explain my error.

Answer 1

The issue is using DataFormat.PLAIN_TEXT. This means JavaFX considers the data format to be just what it says on the tin: text, i.e. String data. This is not really the case. There is no static member of DataFormat that refers to a suitable DataFormat, so you need to create one on your own:
final String mimeType = "application/javafx-entrylist"; // TODO: choose properly
// use existing format or introduce new one
DataFormat f = DataFormat.lookupMimeType(mimeType);
final DataFormat format = f == null ? new DataFormat(mimeType) : f;
setOnDragDetected(event -> {
Dragboard db = startDragAndDrop(TransferMode.ANY);
ClipboardContent clipboardContent = new ClipboardContent();
clipboardContent.put(format, treeElement.getEntities());
db.setContent(clipboardContent);
System.out.println(db.getContent(format));
event.consume();
});
setOnDragDropped(event -> {
Dragboard db = event.getDragboard();
if (db.hasContent(format)) {
System.out.println(db.getContent(format));
System.out.println("Accept Drop");
}
event.consume();
});