Delphi中Tlist实例

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    btn1: TButton;
    btn2: TButton;
    btn3: TButton;
    btn4: TButton;
    procedure btn1Click(Sender: TObject);
    procedure btn2Click(Sender: TObject);
    procedure btn3Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var

  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.btn1Click(Sender: TObject);

var
  List: TList;
      {声明 List}
  frmRed: TForm;                     {用于测试的对象, 这里选择了窗体}
begin
  List := TList.Create;              {建立列表}

  frmRed := TForm.Create(nil);       {建立 frmRed}
  frmRed.Caption:=‘red‘;         {frmRed 标题}
  frmRed.Color := clRed;          {frmRed 颜色}
  
  List.Add(frmRed);                  {添加到列表}

  frmRed:=TForm.Create(nil);     {又建立个frmred}
  frmRed.Caption:=‘bre‘;         {frmred 标题}
  frmRed.Color :=clBlue;          {frmred 颜色}
  List.Add(frmRed);                  {添加到列表}

  ShowMessage(IntToStr(List.Count)); {1; 列表元素总数}
  //TForm(List.Items[0]).ShowModal;  {调用对象}
  TForm(List[0]).ShowModal;         {调用对象, 比上一行的写法简洁, 但是一样的}
  TForm(List[1]).ShowModal;
  frmRed.Free;
  List.Free;
end;

procedure TForm1.btn2Click(Sender: TObject);
// Insert、Remove、Delete、Clear、First、Last
var
  List: TList;                       
  frmRed,frmGreen,frmBlue: TForm;
  i: Integer;
begin
  List := TList.Create;

  {建立两个窗体: 红色、绿色}
  frmRed := TForm.Create(nil);
  frmRed.Caption := ‘Red‘;
  frmRed.Color := clRed;

  frmGreen := TForm.Create(nil);
  frmGreen.Caption := ‘Green‘;
  frmGreen.Color := clGreen;

  {添加到 List}
  List.Add(frmRed);
  List.Add(frmGreen);

  {再建立一个蓝色窗体}
  frmBlue := TForm.Create(nil);
  frmBlue.Caption := ‘Blue‘;
  frmBlue.Color := clBlue;

  {插入到 List}
  List.Insert(0, frmBlue);

  ShowMessage(IntToStr(List.Count)); {3}
  TForm(List.First).ShowModal;       {显示第一个: 蓝色窗体}
  TForm(List.Last).ShowModal;        {显示最后一个: 绿色窗体}

  {看看红色窗体是第几个?}
  i := List.IndexOf(frmRed);
  ShowMessage(IntToStr(i));          {1; 是第二个}

  {从列表中删除 - 用对象指针}
  List.Remove(frmRed);
  ShowMessage(IntToStr(List.Count)); {2}
  frmRed.ShowModal;                  {frmRed 依然存在, 只是不在列表中了}

  {从列表中删除 - 用元素索引}
  List.Delete(0);
  frmBlue.ShowModal;                 {frmBlue 依然存在, 只是不在列表中了}

  {清空列表}
  List.Clear;

  frmRed.Free;
  frmGreen.Free;
  frmBlue.Free;
  List.Free;
end;

procedure TForm1.btn3Click(Sender: TObject);
// Capacity、Move、Exchange、Extract
var
  List: TList;                       
  frmRed,frmGreen,frmBlue: TForm;
  p: Pointer;
  i: Integer;
begin
  List := TList.Create;

  List.Capacity := 3; {让 List 准备好接受 3 个元素}

  {建立红、绿、蓝三个窗体, 并添加到 List}
  frmRed := TForm.Create(nil);
  frmRed.Caption := ‘Red‘; frmRed.Color := clRed;
  frmGreen := TForm.Create(nil);
  frmGreen.Caption := ‘Green‘; frmGreen.Color := clGreen;
  frmBlue := TForm.Create(nil);
  frmBlue.Caption := ‘Blue‘; frmBlue.Color := clBlue;
  List.Add(frmRed);
  List.Add(frmGreen);
  List.Add(frmBlue);

  {依次显示窗体标题}
  for i := 0 to List.Count - 1 do
    ShowMessage(TForm(List[i]).Caption); {将分别显示: Red Green Blue}

  {移动}
  List.Move(2,0); {把第 3 个转移到第 1 个}
  for i := 0 to List.Count - 1 do
    ShowMessage(TForm(List[i]).Caption); {将分别显示: Blue Red Green}

  {置换}
  List.Exchange(1,2); {把第 2 个与第 3 个交换}
  for i := 0 to List.Count - 1 do
    ShowMessage(TForm(List[i]).Caption); {将分别显示: Blue Green Red}

  {提取指针}
  p := List.Extract(frmGreen);
  ShowMessage(TForm(p).Caption);         {Green}

  frmRed.Free;
  frmGreen.Free;
  frmBlue.Free;
  List.Free;
end;

end.