delphi 2009 泛型容器单元(Generics.Collections)[5]: TObject...<T> 系列

已经有了: TList、TQueue、TStack、TDictionary

为什么还有: TObjectList、TObjectQueue、TObjectStack、TObjectDictionary ?

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 会同时释放对象, 而 Generics.Collections.TList 不会.

其他也是一样.

还是要做个例子测试一下:

本例效果图:

代码文件:

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; {譬如要管理 TButton 对象}

ObjList : TObjectList;

procedure TForm1.FormCreate(Sender: TObject);

begin

List := TList.Create;

ObjList := TObjectList.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.

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