How to identify Delphi StringList object is created or not

Question

I have declared variable of TStringList in private section. In a button click event I want to access that TStringList object.

sVariable:= TStringList.Create;
sVariable.add('Test1');

Now whenever i click on that button each time its newly created and memory is allocated to that variable. Is there any property/function using which we can determine object is created for that variable or not and it will not give the access violation error also?

Answer 1

if not Assigned(sVariable) then
  sVariable:= TStringList.Create;
sVariable.add('Test1');

Answer 2

Another way to approach it, expanding on David's answer, is through a property with a read method.

TMyForm = class (TForm)
private
  FStrList : TStringList;
public
  property StrList : TStringList read GetStrList;
  destructor Destroy; override;
end;

implementation

function TMyForm.GetStrList : TStringList;
begin
  if not Assigned(FStrList) then
    FStrList := TStringList.Create;
  Result := FStrList;
end;

destructor TMyForm.Destroy;
begin
  FStrList.Free;
  inherited;
end;

Edit: Added the Free call in an overridden destructor.