Delphi TStringList Find 方法找不到项目

Question

我正在编写自己的类来管理 android/ios 应用程序的翻译，并且我已经生成了这段代码。我将解释下面的代码，但它非常简单和简短。

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.

上面的代码使用如下：

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;

TLocalization 类完成所有工作。如您所见，我创建了变量a，然后向类添加了一种语言（这是在内部使用字典/字符串列表进行管理的）。

我可以使用Locale[Index: string] 属性访问我添加的语言，该属性返回一个TLanguage，我用一个类来指示单个语言。最后使用 localize 方法，我得到了我的翻译。

---

奇怪的是，我总是收到错误'Locale not found'。任何的想法？使用调试器我发现了这一点：

FLocaleList 有项目，但我已经对此进行了测试，我想我在第 71 行（我使用 Find 函数）做错了什么。我是否错误地传递了索引？

Answer 1

您的代码逻辑是倒退的。 Find() 如果找到匹配项，则返回 True，否则返回 False。如果 Find() 返回 False，则您正在访问 Items[]，如果返回 True，则引发异常。您需要在 if 语句中删除 not：

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;

但是，更重要的是，Find() documentation 说：

注意：仅将Find 用于排序列表。对于未排序的列表，请改用 IndexOf 方法。

您的列表未排序，因为 Sorted 属性默认为 false。所以请改用IndexOf()：

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;