Delete Multiple rows from Nattable - eclipse-rcp

Question

I am trying to delete more than one row from NatTable. Following the solution described in Delete rows from Nattable. I have created a the following classes:
the Command class looks like this :
public class DeleteMultiRowCommand extends AbstractMultiRowCommand {
public DeleteMultiRowCommand(AbstractMultiRowCommand command) {
super(command);
}
protected DeleteMultiRowCommand(ILayer layer, int[] rowPositions) {
super(layer, rowPositions);
}
#Override
public ILayerCommand cloneCommand() {
return new DeleteMultiRowCommand(this);
}
}
Command Handler class:
public class DeleteMultiRowCommandHandler<T> implements ILayerCommandHandler<DeleteMultiRowCommand> {
private List<T> bodyData;
private SelectionLayer layer;
public DeleteMultiRowCommandHandler(List<T> bodyData, SelectionLayer selectionLayer) {
this.bodyData = bodyData;
this.layer = selectionLayer;
}
public DeleteMultiRowCommandHandler(List<T> bodyData){
this.bodyData = bodyData;
}
#Override
public Class<DeleteMultiRowCommand> getCommandClass() {
return DeleteMultiRowCommand.class;
}
#Override
public boolean doCommand(ILayer targetLayer, DeleteMultiRowCommand command) {
//convert the transported position to the target layer
if (command.convertToTargetLayer(targetLayer)) {
Collection<Integer>rowpos = command.getRowPositions();
//remove the element
for(Integer val : rowpos){
this.bodyData.remove(val.intValue());
targetLayer.fireLayerEvent(new RowDeleteEvent(targetLayer, val.intValue()));
}
return true;
}
return false;
}
}
and the Command will be triggered on clicking a MenuItem
this.contextMenu = new PopupMenuBuilder(natTable)
.withInspectLabelsMenuItem()
.withClearAllFilters()
.withColumnRenameDialog()
.withMenuItemProvider(new IMenuItemProvider() {
#Override
public void addMenuItem(final NatTable natTable, Menu popupMenu) {
MenuItem deleteRow = new MenuItem(popupMenu, SWT.PUSH);
deleteRow.setText("Delete Row(s)");
deleteRow.setEnabled(true);
deleteRow.addSelectionListener(new SelectionAdapter() {
#Override
public void widgetSelected(SelectionEvent event) {
//int rowPosition = MenuItemProviders.getNatEventData(event).getRowPosition();
ILayer bl = ((GridLayer)natTable.getLayer()).getBodyLayer();
BodyLayerStack bl1 = (BodyLayerStack) bl;
SelectionLayer sl = bl1.getSelectionLayer();
int []poss = new int[sl.getFullySelectedRowPositions().length];
int i=0;
for(int pos1 : sl.getFullySelectedRowPositions()){
poss[i]=sl.getRowIndexByPosition(pos1);
i++;
}
//System.out.println("Menu item selected "+rowPosition);
//natTable.doCommand(new DeleteRowCommand(natTable, rowPosition));
natTable.doCommand(new DeleteMultiRowCommand(natTable, poss));
}
});
}
})
.build();
when I try to delete the rows, rows which not selected are deleted. Seems like an issue with the row postion to row index conversion. is the row postion to row index conversion correct within my IMenuItemProvider right ?

Answer 1

It seems like you do the conversion from position to index twice: once in the menu item selection listener and once in the command handler (by calling convertToTargetLayer). The first is not necessary.

Answer 2

That is not an issue of NatTable, but an issue on how to work with collections. You need to remove the items backwards if you remove the elements one by one. Otherwise the items for the indexes are changing while processing.
Let's assume you want to delete the elements at index 1 and 2. After removing the element at index 1, the elements below will move up. So the element that was before on index 2 will be on index 1 now, and the element at index 3 will be on index 2. Therefore the removal of the element at index 2 in the next iteration will remove the item that was before on index 3.
I'd suggest to sort and reverse the collection of indexes before iterating to remove items from the collection. Than it should work.