TList<T>抛出异常

Question

我有以下代码：

program Tlist;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  madExcept,
  madLinkDisAsm,
  madListHardware,
  madListProcesses,
  madListModules,
  System.Generics.Collections,
  System.SysUtils;

type
  TMyItem = class(TInterfacedObject)
  private
    ItemPrice: Currency;
  public
    constructor Create(const aItemPrice: Currency); reintroduce;
  end;

  IMyList = interface
    ['{1D11BD29-5C1E-4171-B67E-FB9157DCB021}']
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
  end;

  TMyList = class(TInterfacedObject, IMyList)
  private
    FList: array of TList<TMyItem>;
  public
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
  end;

{ TMyList }

function TMyList.Add(const aPrice, aItemN: Integer): Integer;
begin
  FList[aItemN].Add(TMyItem.Create(aPrice));
  Result := FList[aItemN].Count;
end;

function TMyList.Reset(const aItems: Integer): Integer;
var
  I: Integer;
begin
  SetLength(FList, 0);
  SetLength(FList, aItems);
  for I := 0 to Length(FList) - 1 do
  begin
    FList[I] := TList<TMyItem>.Create;
  end;
  Result := Length(FList);
end;

{ TMyItem }

constructor TMyItem.Create(const aItemPrice: Currency);
begin
  ItemPrice := aItemPrice;
end;

var
  MyList: IMyList;

begin
  MyList := TMyList.Create;
  MyList.Reset(3);
  mylist.Add(1000, 1);
end.

执行时，它会抛出一个链接到TList<T>的异常。

由于TList实现了引用计数，而且所有的类都是从TInterfacedObject派生出来的，因此我的印象是内存将自动释放，但很明显，我错了。

我做错了什么？

编辑

根据这些建议，我提出了以下代码：

program Tlist2;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  madExcept,
  madLinkDisAsm,
  madListHardware,
  madListProcesses,
  madListModules,
  System.Generics.Collections,
  System.SysUtils;

type
  IMyItem = interface
    ['{2EB53CC3-E5FC-474B-A162-30BBD2D17C48}']
  end;

  TMyItem = class(TInterfacedObject, IMyItem )
  private
    ItemPrice: Currency;
  public
    constructor Create(const aItemPrice: Currency); reintroduce;
  end;

  IMyList = interface
    ['{1D11BD29-5C1E-4171-B67E-FB9157DCB021}']
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
  end;

  TMyList = class(TInterfacedObject, IMyList)
  private
    FList: array of TList<TMyItem>;
  public
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
    destructor Destroy; override;
  end;

{ TMyList }

function TMyList.Add(const aPrice, aItemN: Integer): Integer;
begin
  FList[aItemN].Add(TMyItem.Create(aPrice));
  Result := FList[aItemN].Count;
end;

destructor TMyList.Destroy;
var
  I: Integer;
  a: Integer;
begin
  for I := 0 to Length(FList) - 1 do
  begin
    if FList[I].Count > 0 then
    begin
      for a := 0 to FList[I].Count - 1 do
      begin
        FList[I][a].Destroy
      end;
    end;
    FList[I].Destroy;
  end;
  inherited;
end;

function TMyList.Reset(const aItems: Integer): Integer;
var
  I: Integer;
begin
  SetLength(FList, 0);
  SetLength(FList, aItems);
  for I := 0 to Length(FList) - 1 do
  begin
    FList[I] := TList<TMyItem>.Create;
  end;
  Result := Length(FList);
end;

{ TMyItem }

constructor TMyItem.Create(const aItemPrice: Currency);
begin
  ItemPrice := aItemPrice;
end;

var
  MyList: IMyList;


begin
  MyList := TMyList.Create;
  MyList.Reset(3);
  mylist.Add(1000, 1);
end.

这样做很好，没有更多的内存泄漏，但我的印象是，我错过了一些东西在这里。我认为，通过使用接口并从TInterfacedObject派生类，驱逐舰就没有必要了。

Answer 1

根据David和Remi的输入，我修改了我的代码：

program Tlist3;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  madExcept,
  madLinkDisAsm,
  madListHardware,
  madListProcesses,
  madListModules,
  System.Generics.Collections,
  System.SysUtils;

type
  IMyItem = interface
    ['{2EB53CC3-E5FC-474B-A162-30BBD2D17C48}']
  end;

  TMyItem = class(TInterfacedObject)
  private
    ItemPrice: Currency;
  public
    constructor Create(const aItemPrice: Currency); reintroduce;
  end;

  IMyList = interface
    ['{1D11BD29-5C1E-4171-B67E-FB9157DCB021}']
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
  end;

  TMyList = class(TInterfacedObject, IMyList)
  private
    FList: array of TObjectList<TMyItem>;
  public
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
    destructor Destroy; override;
  end;

{ TMyList }

function TMyList.Add(const aPrice, aItemN: Integer): Integer;
begin
  FList[aItemN].Add(TMyItem.Create(aPrice));
  Result := FList[aItemN].Count;
end;

destructor TMyList.Destroy;
var
  I: Integer;
  a: Integer;
begin
  if Length(FList) > 0 then
  begin
    for I := 0 to Length(FList) - 1 do
    begin
      FList[I].Free;
    end;
  end;
  inherited;
end;

function TMyList.Reset(const aItems: Integer): Integer;
var
  I: Integer;
begin
  if Length(FList) > 0 then
  begin
    for I := 0 to Length(FList) - 1 do
    begin
      FList[I].Free;
    end;
  end;
  SetLength(FList, 0);
  SetLength(FList, aItems);
  for I := 0 to Length(FList) - 1 do
  begin
    FList[I] := TObjectList<TMyItem>.Create;
  end;
  Result := Length(FList);
end;

{ TMyItem }

constructor TMyItem.Create(const aItemPrice: Currency);
begin
  ItemPrice := aItemPrice;
end;

var
  MyList: IMyList;


begin
  MyList := TMyList.Create;
  MyList.Reset(3);
  mylist.Add(1000, 1);
  mylist.Add(2000, 2);
  MyList.Reset(2);
  mylist.Add(1000, 0);
  mylist.Add(2000, 1);
end.

没有内存泄漏。