https://stackoverflow.com/questions/18043685
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RussianCheck you dragboard.hasString(). Definitely it should return FALSE in case of dragboard.getString() is null. So, you never reach int incomingIndex = Integer.parseInt(dragboard.getString());, because you won't pass trough if (dragboard.hasString())
If you can't find the problem paste your Dragboard class implementation.
EDIT:
Well this will be more robust:
private Node createNode() {
final BorderPane bp = new BorderPane();
bp.setOnDragDetected(new EventHandler<MouseEvent>() {
@Override
public void handle(MouseEvent event) {
Dragboard db = bp.startDragAndDrop(TransferMode.MOVE);
ClipboardContent clipboard = new ClipboardContent();
final int nodeIndex = bp.getParent().getChildrenUnmodifiable()
.indexOf(bp);
clipboard.putString(Integer.toString(nodeIndex));
db.setContent(clipboard);
event.consume();
}
});
bp.setOnDragOver(new EventHandler<DragEvent>() {
@Override
public void handle(DragEvent event) {
boolean accept = true;
final Dragboard dragboard = event.getDragboard();
if (dragboard.hasString()) {
try {
int incomingIndex = Integer.parseInt(dragboard.getString());
int myIndex = bp.getParent().getChildrenUnmodifiable()
.indexOf(bp);
if (incomingIndex == myIndex) {
accept = false;
}
} catch(java.lang.NumberFormatException e) {
//handle null or not number string in clipboard
accept = false;
}
} else {
accept = false;
}
if (accept) {
event.acceptTransferModes(TransferMode.MOVE);
}
}
});
bp.setOnDragDropped(new EventHandler<DragEvent>() {
@Override
public void handle(DragEvent event) {
boolean success = false;
final Dragboard dragboard = event.getDragboard();
if (dragboard.hasString()) {
try {
int incomingIndex = Integer.parseInt(dragboard.getString());
final Pane parent = (Pane) bp.getParent();
final ObservableList<Node> children = parent.getChildren();
int myIndex = children.indexOf(bp);
final int laterIndex = Math.max(incomingIndex, myIndex);
Node removedLater = children.remove(laterIndex);
final int earlierIndex = Math.min(incomingIndex, myIndex);
Node removedEarlier = children.remove(earlierIndex);
children.add(earlierIndex, removedLater);
children.add(laterIndex, removedEarlier);
success = true;
} catch(java.lang.NumberFormatException e) {
//handle null or not number string in clipboard
}
}
event.setDropCompleted(success);
}
});
bp.setMinSize(50, 50);
return bp;
}
