详测 Generics Collections TList (11): Create

unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls;



type

  TForm1 = class(TForm)

    Button1: TButton;

    Button2: TButton;

    Button3: TButton;

    procedure Button1Click(Sender: TObject);

    procedure Button2Click(Sender: TObject);

    procedure Button3Click(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



uses Generics.Collections, Generics.Defaults;



var

  i: Integer;

  str: string;



//无参数的建立

procedure TForm1.Button1Click(Sender: TObject);

var

  List: TList<Integer>;

begin

  List := TList<Integer>.Create();



  List.AddRange([11,22,33]);

  str := '';

  for i in List do str := str + IntToStr(i) + ' ';

  ShowMessage(str); {11 22 33 }



  List.Free;

end;



//可以基于另一个列表建立

procedure TForm1.Button2Click(Sender: TObject);

var

  List,ListTmp: TList<Integer>;

begin

  ListTmp := TList<Integer>.Create();

  ListTmp.AddRange([1, 2, 3]);



  List := TList<Integer>.Create(ListTmp);



  str := '';

  for i in List do str := str + IntToStr(i) + ' ';

  ShowMessage(str); {1 2 3 }



  ListTmp.Free;

  List.Free;

end;



//可在建立时同时指定排序器

procedure TForm1.Button3Click(Sender: TObject);

var

  List: TList<Integer>;

  Comparer: IComparer<Integer>;

begin

  {建立排序器}

  Comparer := TComparer<Integer>.Construct(

    function(const n1,n2: Integer): Integer

    begin

      Result := n2 - n1;

    end

  );



  List := TList<Integer>.Create(Comparer);

  List.AddRange([2, 3, 1]);



  List.Sort; {会根据建立时指定的排序器排序}



  str := '';

  for i in List do str := str + IntToStr(i) + ' ';

  ShowMessage(str); {3 2 1 }



  List.Free;

end;



end.