Re: [Java-gnome-developer] Question: TreeView & TreeStore and Listeners

[Luca De R. <pie...@li...>]

Il mar, 2004-02-03 alle 21:20, Alex Moreno ha scritto:
> The last days i've been working with trees.
> 
> I've found a way of getting selected rows. I don't know is this is a
> correct way of doing it. I'd much appreciate corrections o opinions. The
> way which i'm discovering which row is selected is iterating over the
> tree until i foun the row. Then, i make all the desired work:
> 
> TreeIter iter = tree.getModel().getFirstIter();
> Boolean exit = Boolean.False;
> do{     
>   //if the searched row is equals the actual row
>  if (win.tree.getSelection().getSelected(iter)) {
>    System.out.println(tree.getModel().getValue(iter,win.dataBlock));
>    exit = Boolean.TRUE;
> 
>  }
> }while(tree.getModel().moveIterNext(iter) && !exit.booleanValue()))
> 
> where 
> 	DataBlockString dataBlock = new DataBlockString();
>         [....]
> DataBlock data[] = new DataBlock[] { dataBlock, dataBlock2, ...}
> 
> 
> As I said, corrections a comments are wellcome :-).

I would simply use:

if ((event.getType()) == TreeSelectionEvent.Type.CHANGED) {							
	TreeIter anIter = treeStore.getFirstIter();
	while (!(anIter == null && selection.getSelected(anIter))) {
		anIter = treeStore.getNextIter(anIter);  
	}
	if (anIter != null) {								
		rowSelected = Integer.parseInt((treeStore.getPath(anIter)).toString());
	       //System.out.println("row n." + rowSelected + " selected");
	} else
		rowSelected = -1;							
}				

So you can get the selected row simply getting the rowSelected int.

Also note that since the CHANGED event is only a hint, you have to
expect that it's possible that 0 rows are actually selected.
I haven't tried your code, but for the above reason it could launch a
NullPointerException when it reaches the end of the tree rows without
finding a selected one (or when performed on an empty treeview), so you
have to check that anIter != null.

I also have a smart algorithm to remove multiple selected rows from a
treeview. It  is:

public void removeButtonClicked() {
	TreePath path = new TreePath("0");
	//stop at the end of the list
	while (store.getIter(path) != null) { 
		//remove contiguous selected rows
		while (mySelection.getSelected(path))
			store.removeRow(store.getIter(path));
		//step ahead until an unselected row or null is found
	   	while (!mySelection.getSelected(path) && store.getIter(path) != null)  
			path.next();
		}
	}


As you can see there are 3 while cycles in it.
Does anyone have a nicer/faster algorithm ?

-- 
Luca De Rugeriis <pie...@li...>