🚀 go-pugleaf

Java works with whatever was returned by your table model. If you do not 
want for the value to be copied, do not copy it.

- Alexey.

Richard M. Ulrich wrote:
> Hello,
> 
> I have a JTable whose TableModel stores data in an ArrayList of ArrayLists. 
> Perhaps because I am more used to C++ (where I know exactly where my data 
> resides), I am having trouble editing cell entries.
> 
> Stripped to its essentials, the code to edit an entry is as follows, where 
> ds is an instance of an implemented AbstractTableModel
> 
>             Element elem = (Element) ds.getObjectAt(gridrow, gridcol);
>             eresults.copy(elem.results); 
> //puts new results into elem.results
>             ds.setValueAt((Object) elem,gridrow,gridcol);
> 
> Again stripping out all of the code to handle error checking and such, 
> getObjectAt is equivalent to two lines:
> 
>             ArrayList aRow = (ArrayList) table.get(gridrow);
>             return ( aRow.get(columnIndex) );
> 
> and setValueAt to two lines
> 
>             ArrayList aRow = (ArrayList) table.get(gridrow);
>             aRow.set(gridcol, elem);
> 
> 
> Now for the dumb questions.  When I have ds.getObjectAt(gridrow, gridcol), 
> am I getting a new copy of the data, or a reference to the existing data? 
> When I have ds.setValueAt((Object) elem,gridrow,gridcol), is Java creating a 
> new copy of elem, or is the ArrayList now pointing to the local object?  If 
> it is the second case, then it would seem like I don't really need to call 
> setValueAt, except for the side-effect of calling fireTableCellUpdated().
> 
> Thanks,
> Richard
> 
> 

-- 
Alexey N. Solofnenko {trelony at gmail.com}
home: http://trelony.cjb.net/