已經有了: TList<T>、TQueue<T>、TStack<T>、TDictionary<TKey,TValue>
為什麼還有: TObjectList<T>、TObjectQueue<T>、TObjectStack<T>、TObjectDictionary<TKey,TValue> ?
還記得 Classes.TList 和 Contnrs.TObjectList 的主要區別嗎?
如果元素是對象, Contnrs.TObjectList 在刪除元素時會同時釋放對象, 而 Classes.TList 不會.
同樣在這裡, Generics.Collections.TObjectList<T> 會同時釋放對象, 而 Generics.Collections.TList<T> 不會.
其他也是一樣.
還是要做個例子測試一下: 本例效果圖:
代碼文件: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 對象}
ObjList : TObjectList<TButton>;
procedure TForm1.FormCreate(Sender: TObject);
begin
List := TList<TButton>.Create;
ObjList := TObjectList<TButton>.Create;
Button1.Caption := '創建 Button 並添加到 TList';
Button2.Caption := '刪除 TList 中的 Button';
Button3.Caption := '創建 Button 並添加到 TObjectList';
Button4.Caption := '刪除 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.
窗體文件:
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
