三、Delphi 2009 泛型容器单元(Generics.Collections)[2]: TQueue<T>
TQueue 和 TStack, 一个是队列列表, 一个是堆栈列表; 一个是先进先出, 一个是先进后出.
TQueue 主要有三个方法、一个属性:
Enqueue(入列)、Dequeue(出列)、Peek(查看下一个要出列的元素);
Count(元素总数).
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm1 = class(TForm)
Memo1: TMemo;
Button1: TButton;
Button2: TButton;
Button3: TButton;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure Button3Click(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
uses Generics.Collections; {Delphi 2009 新增的泛型容器单元}
type
TRec = record
Name: string;
Age: Word;
end;
var
Queue: TQueue<TRec>; {定义一个泛型 TQueue 类, 这指定了要用于上面定义的 TRec 记录}
{建立}
procedure TForm1.FormCreate(Sender: TObject);
begin
Queue := TQueue<TRec>.Create;
Memo1.Clear;
Button1.Caption := Button1.Caption + ' 入列';
Button2.Caption := Button2.Caption + ' 出列';
Button3.Caption := Button3.Caption + ' 下一个出列的
';
end;
{释放}
procedure TForm1.FormDestroy(Sender: TObject);
begin
Queue.Free;
end;
{入列: Enqueue}
procedure TForm1.Button1Click(Sender: TObject);
var
rec: TRec;
begin
rec.Name := StringOfChar(Char(65 + Random(26)), 3);
rec.Age := Random(150);
Queue.Enqueue(rec);
Text := Format('当前队列成员总数: %d', [Queue.Count]);
{让 Memo1 配合显示}
Memo1.Lines.Add(Format('%s, %d', [rec.Name, rec.Age]));
end;
{出列: Dequeue}
procedure TForm1.Button2Click(Sender: TObject);
var
rec: TRec;
begin
if Queue.Count = 0 then Exit;
rec := Queue.Dequeue;
ShowMessage(Format('%s, %d', [rec.Name, rec.Age]));
Text := Format('当前队列成员总数: %d', [Queue.Count]);
{让 Memo1 配合显示}
Memo1.Lines.Delete(0);
end;
{下一个出列的元素: Peek}
procedure TForm1.Button3Click(Sender: TObject);
var
rec: TRec;
begin
if Queue.Count = 0 then Exit;
rec := Queue.Peek;
ShowMessage(Format('%s, %d', [rec.Name, rec.Age]));
end;
end.
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm1 = class(TForm)
Memo1: TMemo;
Button1: TButton;
Button2: TButton;
Button3: TButton;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure Button3Click(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
uses Generics.Collections; {Delphi 2009 新增的泛型容器单元}
type
TRec = record
Name: string;
Age: Word;
end;
var
Queue: TQueue<TRec>; {定义一个泛型 TQueue 类, 这指定了要用于上面定义的 TRec 记录}
{建立}
procedure TForm1.FormCreate(Sender: TObject);
begin
Queue := TQueue<TRec>.Create;
Memo1.Clear;
Button1.Caption := Button1.Caption + ' 入列';
Button2.Caption := Button2.Caption + ' 出列';
Button3.Caption := Button3.Caption + ' 下一个出列的
';end;
{释放}
procedure TForm1.FormDestroy(Sender: TObject);
begin
Queue.Free;
end;
{入列: Enqueue}
procedure TForm1.Button1Click(Sender: TObject);
var
rec: TRec;
begin
rec.Name := StringOfChar(Char(65 + Random(26)), 3);
rec.Age := Random(150);
Queue.Enqueue(rec);
Text := Format('当前队列成员总数: %d', [Queue.Count]);
{让 Memo1 配合显示}
Memo1.Lines.Add(Format('%s, %d', [rec.Name, rec.Age]));
end;
{出列: Dequeue}
procedure TForm1.Button2Click(Sender: TObject);
var
rec: TRec;
begin
if Queue.Count = 0 then Exit;
rec := Queue.Dequeue;
ShowMessage(Format('%s, %d', [rec.Name, rec.Age]));
Text := Format('当前队列成员总数: %d', [Queue.Count]);
{让 Memo1 配合显示}
Memo1.Lines.Delete(0);
end;
{下一个出列的元素: Peek}
procedure TForm1.Button3Click(Sender: TObject);
var
rec: TRec;
begin
if Queue.Count = 0 then Exit;
rec := Queue.Peek;
ShowMessage(Format('%s, %d', [rec.Name, rec.Age]));
end;
end.
DFM
