Delphi 2009 泛型容器单元(Generics.Collections)[5]: TObject... 系列

已经有了: TList<T>、TQueue<T>、TStack<T>、TDictionary<TKey,TValue>
为什么还有: TObjectList<T>、TObjectQueue<T>、TObjectStack<T>、TObjectDictionary<TKey,TValue> ?

还记得 Classes.TList 和 Contnrs.TObjectList 的主要区别吗?
如果元素是对象, Contnrs.TObjectList 在删除元素时会同时释放对象, 而 Classes.TList 不会.

同样在这里, Generics.Collections.TObjectList<T> 会同时释放对象, 而 Generics.Collections.TList<T> 不会.
其他也是一样.

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还是要做个例子测试一下:

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本例效果图:

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代码文件:

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unit Unit1;



interface



uses

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

  Dialogs, StdCtrls, ExtCtrls;



type

  TForm1 = class(TForm)

    Panel1: TPanel;

    Panel2: TPanel;

    Button1: TButton;

    Button2: TButton;

    Button3: TButton;

    Button4: TButton;

    procedure FormCreate(Sender: TObject);

    procedure FormDestroy(Sender: TObject);

    procedure Button1Click(Sender: TObject);

    procedure Button2Click(Sender: TObject);

    procedure Button3Click(Sender: TObject);

    procedure Button4Click(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



uses Generics.Collections;



var

  List    : TList<TButton>;       {譬如要管理 TButton 对象}

  ObjList : TObjectList<TButton>;



procedure TForm1.FormCreate(Sender: TObject);

begin

  List := TList<TButton>.Create;

  ObjList := TObjectList<TButton>.Create;



  Button1.Caption := '创建 Button 并添加到 TList';

  Button2.Caption := '删除 TList 中的 Button';

  Button3.Caption := '创建 Button 并添加到 TObjectList';

  Button4.Caption := '删除 TObjectList 中的 Button';



  Button2.Enabled := False;

  Button4.Enabled := False;

end;



procedure TForm1.FormDestroy(Sender: TObject);

begin

  List.Free;

  ObjList.Free;

end;



procedure TForm1.Button1Click(Sender: TObject);

var

  btn: TButton;

begin

  btn := TButton.Create(Self);

  btn.Caption := 'TList 中的 Button';

  btn.Parent := Panel1;

  btn.Width := 132;

  List.Add(btn);



  Button1.Enabled := False;

  Button2.Enabled := True;

end;



procedure TForm1.Button2Click(Sender: TObject);

begin

  List.RemoveAt(0);



  Button1.Enabled := True;

  Button2.Enabled := False;

end;



procedure TForm1.Button3Click(Sender: TObject);

var

  btn: TButton;

begin

  btn := TButton.Create(Self);

  btn.Caption := 'TObjectList 中的 Button';

  btn.Parent := Panel2;

  btn.Width := 132;

  ObjList.Add(btn);



  Button3.Enabled := False;

  Button4.Enabled := True;

end;



procedure TForm1.Button4Click(Sender: TObject);

begin

  ObjList.RemoveAt(0);



  Button3.Enabled := True;

  Button4.Enabled := False;

end;



end.


 
   

窗体文件:

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object Form1: TForm1

  Left = 0

  Top = 0

  Caption = 'Form1'

  ClientHeight = 153

  ClientWidth = 408

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  OnCreate = FormCreate

  OnDestroy = FormDestroy

  PixelsPerInch = 96

  TextHeight = 13

  object Panel1: TPanel

    Left = 8

    Top = 8

    Width = 193

    Height = 137

    Caption = 'Panel1'

    TabOrder = 0

    object Button1: TButton

      Left = 8

      Top = 76

      Width = 177

      Height = 25

      Caption = 'Button1'

      TabOrder = 0

      OnClick = Button1Click

    end

    object Button2: TButton

      Left = 8

      Top = 107

      Width = 177

      Height = 25

      Caption = 'Button2'

      TabOrder = 1

      OnClick = Button2Click

    end

  end

  object Panel2: TPanel

    Left = 207

    Top = 8

    Width = 194

    Height = 137

    Caption = 'Panel2'

    TabOrder = 1

    object Button3: TButton

      Left = 8

      Top = 76

      Width = 177

      Height = 25

      Caption = 'Button3'

      TabOrder = 0

      OnClick = Button3Click

    end

    object Button4: TButton

      Left = 8

      Top = 107

      Width = 177

      Height = 25

      Caption = 'Button4'

      TabOrder = 1

      OnClick = Button4Click

    end

  end

end