Re: Drag and drop for non-String objects

Hendrik Maryns <>
Mon, 21 Jul 2008 16:34:51 +0200
Hash: SHA1

Nigel Wade schreef:
| Hendrik Maryns wrote:
|> Hash: SHA1
|> Hi all,
|> I???d like to revive a thread I started a while ago but which got no
|> satisfying answers.
|> I want to implement drag and drop for non-String objects.
|> Setting: a JList with a DefaultListModel. It contains Formula???s (a
|> class of my own making, with a whole hierarchy underneath it:
|> Conjunction, Negation etc.). I then do
|> result.setDragEnabled(true);
|> result.setTransferHandler(new FormulaTransferHandler());
|> result.setDropMode(DropMode.INSERT);
|> on the JList. Here follows an almost minimal SSCCE, note that it needs
|> Java 6:
| Here you specify that the DataFlavor which drop will accept is of class
| Formula...
|> ~ this.localFormulaFlavor = new ActivationDataFlavor(Formula.class,
|> ~ DataFlavor.javaJVMLocalObjectMimeType, "Arrays of formulas");
|> ~ }
|> ~ /**
|> ~ * The data flavor for formulas local to the JVM.
|> ~ */
|> ~ private final DataFlavor localFormulaFlavor;
|> ~ /**
|> ~ * The formulas being transfered.
|> ~ */
|> ~ private Object[] transferedFormulas = null;
|> ~ @Override
|> ~ protected Transferable createTransferable(final JComponent c) {
|> ~ final JList formulaList = (JList) c;
|> ~ this.transferedFormulas = formulaList.getSelectedValues();
|> ~ return new DataHandler(this.transferedFormulas,
|> ~ .getMimeType());
|> ~ // TODO: add support via serialization?
|> ~ }
| ..but what you actually transfer is an Object[]

I see. What solution would you suggest: convert the Object[] to
Formula[] and update above also, or simply use Object as the local
flavor above and let the JList find out? I guess there is no need for
Formula indeed, since I do not invoke any methods on it, so I could as
well use Object[].

I wonder whether some day the Swing classes will start using generics as
well. It would make things much easier.

Thanks, H.
- --
Hendrik Maryns
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