var
 iValue: integer;
begin
 if not TryStrToInt(Edit1.Text,iValue) then
  ShowMessage('Harus angka euy!!!');
end;

procedure TForm1.Edit1KeyPress(Sender: TObject;
  var Key: Char);
var koma : char;
begin
  koma := decimalseparator;
   if key = koma then
   begin
      if pos(koma,Edit1.Text)>0 then
     begin
         key :=#0;
        exit;
     end;
   end;
   if not (key in ['0'..'9',#8,koma]) then  key:=#0;
end;