List index (-1) out of bounds in ListBox

[Przemyslav]

Hello everybody. I have problem with my ListBox. I get error like this: "List index (-1) out of bounds", when I click on empty space in ListBox.

I have form like this:

https://i.postimg.cc/HW4H5HR3/Bez-tytu-u.png

My code:

Code: Pascal  [Select][+][-]

1. unit Unit1;
2. var
3.   Form1: TForm1;
4.   ulicekmp,ulicekmprecord : TStringList;

Code: Pascal  [Select][+][-]

1. procedure TForm1.RadioGroup1Click(Sender: TObject);
2. var
3.    i : integer;
4. begin
5.      if (RadioGroup1.ItemIndex = 0) then
6.      begin
7.         if FileExists('dat\ulice0-9.dat') then
8.         begin
9.            ulicekmprecord:=TStringList.Create;
10.            ulicekmprecord.Delimiter:=';';
11.            ulicekmprecord.StrictDelimiter:=true;
12.            ulicekmp:=TStringList.Create;
13.            ulicekmp.StrictDelimiter:=true;ulicekmp.LoadFromFile('dat\ulice0-9.dat');
14.            ListBox1.Enabled := true;
15.            ListBox1.Clear;
16.            Memo1.Clear;
17.  
18.            for i:=0 to ulicekmp.Count-1 do
19.            begin
20.               ulicekmprecord.DelimitedText:=ulicekmp.Strings[i];
21.               ListBox1.Items.Add(ulicekmprecord.Strings[0]);
22.            end;
23.         end
24.         else
25.         MessageDlg('Nie odnaleziono pliku: ' + ExtractFilePath(Application.ExeName) + 'dat\ulice0-9.dat' + '.' , mtError, [mbOk], 0 );
26.      end;
27. (...)

Code: Pascal  [Select][+][-]

1. procedure TForm1.ListBox1Click(Sender: TObject);
2. begin
3.       ulicekmprecord.DelimitedText:=ulicekmp.Strings[ListBox1.ItemIndex];
4.       Memo1.Enabled := true;
5.       Memo1.Clear;
6.       Memo1.Append(ulicekmprecord.Strings[1]);
7. end;

So I have file for example "ulice0-9.dat" where I have somethong like this:

abcdefg;12345
hjhgjgfjf;767666
rrturturtitr;7767676
(...)

My file is opened in RadioGroup and imported to 2 stringlists ulicekmp,ulicekmprecord with delimited text (. One part is imported to items of ListBox. When I click on non empty item in ListBox, my program display second part on Memo. I have error "List index (-1) out of bounds" when I click on empty space in ListBox after imported values:

https://i.postimg.cc/dDPTzFR5/Bez-tytu-u.png

How to remove this error?

Sorry for my English, thank you for your help

[lucamar]

Try this:

Code: Pascal  [Select][+][-]

1. procedure TForm1.ListBox1Click(Sender: TObject);
2. begin
3.   {Make sure there's an item selected before trying to use it}
4.   if ListBox1.ItemIndex >= 0 then begin
5.     ulicekmprecord.DelimitedText:=ulicekmp.Strings[ListBox1.ItemIndex];
6.     Memo1.Enabled := true;
7.     Memo1.Clear;
8.     Memo1.Append(ulicekmprecord.Strings[1]);
9.   end;
10. end;

Nota that this is just a minimal check! You should also check that ItemIndex is a valid index for ulicekmp.Strings, etc.

[Przemyslav]

Thank you very much It's working in 2 cases - on item selected before and non selected. Thank you