Handling a Drop Event 
The drop target in this example only accepts dropped String objects. A drop target must implement DropTargetListener and supply an implementation for drop(). 

 public void drop(DropTargetDropEvent evt) {
   try {
     Transferable t = evt.getTransferable();
     
     if (t.isDataFlavorSupported(
       DataFlavor.stringFlavor)) {
         evt.acceptDrop(
           DnDConstants.ACTION_COPY_OR_MOVE);
         String s = (String)t.getTransferData(
           DataFlavor.stringFlavor);
         evt.getDropTargetContext().dropComplete(true);
         process(s);
      } else {
      evt.rejectDrop();
      }
   } catch (IOException e) {
   evt.rejectDrop();
   } catch (UnsupportedFlavorException e) {
   evt.rejectDrop();
   }
 }