delphi - 从 TCheckListBox 到 TcxCheckListBox 有异常吗？

Question

我将此代码与 TCheckListbox (lbServices) 一起使用，并且工作正常。但使用 Devexpress 的 TcxCheckListBox 会引发异常。

procedure TMaintenanceForm.AfterConstruction;
var
  i: Integer;
  ActionObj: TAction;
begin
  inherited;
  for i := 0 to ServiceActionList.ActionCount-1 do
  begin
    ActionObj := ServiceActionList.Actions[i] as TAction;
    lbServices.Items.AddObject(ActionObj.Caption, ActionObj);
  end;
end;

procedure TMaintenanceForm.btnStopClick(Sender: TObject);
begin
  fContinue := False;
end;

procedure TMaintenanceForm.cmdExecuteSelectedClick(Sender: TObject);
var
  i: Integer;
begin
  Screen.Cursor := crHourGlass;
  try
    for i := 0 to lbServices.Count -1 do
      if lbServices.Selected[i] then
        (lbServices.Items.Objects[i] as TAction).Execute;  // Exception here!!!!
  finally
    Screen.Cursor := crDefault;
  end;
end;

如果我调试代码 lbServices.Count = 12。对于列表中的所有项目，lbServices.Items.Objects[i] 均为 nil。这里出了什么问题？

Answer 1

请改用以下代码:

var
  AItem: TcxCheckListBoxItem;
begin
  AItem := cxCheckListBox1.Items.Add;
  AItem.ItemObject := Action1;
  AItem.Text := Action1.Caption;
end;

...

var
  I: Integer;
begin
  for I := 0 to cxCheckListBox1.Items.Count - 1 do
    if cxCheckListBox1.Items[I].Checked then
      (cxCheckListBox1.Items[I].ItemObject as TACtion).Execute;
end;