sorting a listview by one of its subitems

Create an OnCompare event handler. Here is a simple example. This one does a compare based upon the combined string value of the first two columns

procedure TForm1.ListView1Compare(Sender: TObject; Item1, Item2: TListItem; Data: Integer; var Compare: Integer);
begin
     Compare := CompareText(Item1.Caption + Item1.SubItems[0],Item2.Caption + Item2.SubItems[0]);
end;
 
end;

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You can use this events:
1. OnColumnClick: ListViewColumnClick
2. OnCompare: ListViewCompare

if user clicks on the column then listview will sort by this column.
in this events use direction of sorting also,
Direction of sorting saves into Column.Tag
first click - sort asc
second click - sort desc

uses
  Math, StrUtils; 
 
procedure TForm1.ListViewColumnClick(Sender: TObject;
  Column: TListColumn);
begin
 TListView(Sender).Tag := Column.Index;
 if Column.Tag = 0 then
  Column.Tag := 1
 else
  Column.Tag := 0;
 TListView(Sender).AlphaSort;
 if Assigned(TListView(Sender).Selected) then begin
   TListView(Sender).Selected.MakeVisible(false);
   TListView(Sender).Selected.Focused := true
 end
end;
 
function InverseValue(AValue: integer; AInverse: boolean = true): integer;
begin
 Result := AValue;
 if AInverse then
  Result := -AValue
end;
 
procedure TForm1.ListViewCompare(Sender: TObject; Item1,
  Item2: TListItem; Data: Integer; var Compare: Integer);
begin
 with TListView(Sender) do
  if Tag = 0 then
   Compare := InverseValue(CompareText(Item1.Caption, Item2.Caption), Columns[Tag].Tag = 0)
  else
   Compare := InverseValue(CompareText(Item1.SubItems[Tag-1], Item2.SubItems[Tag-1]), Columns[Tag].Tag = 0)
end;

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@SteveBay:

thanks, but all this code does is to throw an exception when i add a new item to the list


@sas13:

thanks, but as i mentioned the user DOES NOT click on the column. There is no column clicking.

i'll try to explain myself better.

One list view with 2 colums (NON CLICKABLE)
list is sorted using the SortType:=stText
in the options windows (where the user sets the options for the program) there is a checkbox that state the following: sort by priority. Priority is the second column (subitem(0))
when the user checks that option that list needs to be sorted by the text in subitem(0).

i hope i explained myself better this time.
again, there is no clicking on columns

thanks