Delphi TStringList Find method cannot find item - delphi

Question

I am writing my own class to manage the translation of android/ios app and I have produced this code. I will explain the code below but it's pretty easy and short.
unit Localization;
interface
uses
System.Classes, System.SysUtils, Generics.Collections, Vcl.Dialogs;
//this class represents a single language (Italian, French, German...)
type
TLanguage = class
private
FTranslationList: TDictionary<string, string>;
function localize(const aWordId: string): string;
public
constructor Create;
destructor Destroy; override;
//methods
procedure addWord(const aIndex, aWord: string);
procedure removeWord(const aIndex: string);
end;
//this is a "container", it gathers all the languages in one place
type
TLocalization = class
private
FLanguagesList: TObjectList<TLanguage>;
FLocaleList: TStringList;
function getLang(Index: string): TLanguage;
public
constructor Create;
destructor Destroy; override;
//methods
function localize(const aLocaleId: string; const aIndex: string): string;
procedure addLanguage(const localeId: string);
//property to manage the languages
property Locale[Index: string]: TLanguage read getLang;
property langCount: integer read getCount;
end;
implementation
{ TLocalization }
{ add a new language to the class. }
{the localeId is a symbol like 'it' that represents the Italian language}
procedure TLocalization.addLanguage(const localeId: string);
begin
//add the language to the languages container
FLanguagesList.Add(TLanguage.Create);
//add the representation of the language.
FLocaleList.Add(localeId);
end;
constructor TLocalization.Create;
begin
FLanguagesList := TObjectList<TLanguage>.Create;
FLocaleList := TStringList.Create;
end;
destructor TLocalization.Destroy;
begin
FLanguagesList.Free;
FLocaleList.Free;
inherited;
end;
//ERROR HERE
function TLocalization.getLang(Index: string): TLanguage;
var i: integer;
begin
{ I search the locale id (for example 'it') if it's in the list. }
{ if it's in the list, I return the respective TLanguage object}
if not( FLocaleList.Find(Index, i) ) then
Result := FLanguagesList.Items[i]
else
raise Exception.Create('Locale not found');
end;
function TLocalization.localize(const aLocaleId, aIndex: string): string;
var k: integer;
begin
k := 0;
if not( FLocaleList.Find(aLocaleId, k) ) then
raise Exception.Create('Locale not found.');
//ho trovato il locale, adesso basta cercare la parola
Result := FLanguagesList.Items[k].localize(aIndex);
end;
{ TLanguage }
procedure TLanguage.addWord(const aIndex, aWord: string);
begin
FTranslationList.Add(aIndex, aWord);
end;
constructor TLanguage.Create;
begin
FTranslationList := TDictionary<string, string>.Create;
end;
destructor TLanguage.Destroy;
begin
FTranslationList.Free;
inherited;
end;
function TLanguage.localize(const aWordId: string): string;
begin
try
Result := FTranslationList.Items[aWordId];
except
Result := 'Not found.';
end;
end;
procedure TLanguage.removeWord(const aIndex: string);
begin
FTranslationList.Remove(aIndex);
end;
end.
The code above is used as follows:
var a: TLocalization;
begin
a := TLocalization.Create;
a.addLanguage('it');
a.addLanguage('cse');
a.Locale['it'].addWord('test', 'Ciao mondo!');
a.Locale['cse'].addWord('test', 'fadfa ea!');
ButtonSomething.Text := a.localize('it', test);
end;
The TLocalization class does all the work. As you can see I create the variable a, then I add a language to the class (this is managed internally using a dictionary/stringlist).
I can access the languages I have added using the Locale[Index: string] property which returns a TLanguage, a class that I use to indicate a single lang. At the end with the localize method I get my translation.
Oddly enough I always get the error 'Locale not found'. Any idea? Using the debugger I have discovered this:
The FLocaleList has items but I have tested this and I guess that I am doing something wrong on line 71 (where I use the Find function). Am I passing wrongly the Index maybe?

Answer 1

Your code logic is backwards. Find() returns True if it finds a match, otherwise it returns False. You are accessing Items[] if Find() returns False, and raising an exception if it returns True. You need to remove the not in your if statement:
function TLocalization.getLang(Index: string): TLanguage;
var
i: integer;
begin
{ I search the locale id (for example 'it') if it's in the list. }
{ if it's in the list, I return the respective TLanguage object}
if FLocaleList.Find(Index, i) then // <-- HERE
Result := FLanguagesList.Items[i]
else
raise Exception.Create('Locale not found');
end;
But, more importantly, the Find() documentation says:
Note: Only use Find with sorted lists. For unsorted lists, use the IndexOf method instead.
Your list is unsorted, as the Sorted property is false by default. So use IndexOf() instead:
function TLocalization.getLang(Index: string): TLanguage;
var
i: integer;
begin
{ I search the locale id (for example 'it') if it's in the list. }
{ if it's in the list, I return the respective TLanguage object}
i := FLocaleList.IndexOf(Index);
if i <> -1 then
Result := FLanguagesList.Items[i]
else
raise Exception.Create('Locale not found');
end;