使用Delphi TThread

Question

这是第一次尝试使用Threads，我正在尝试使用Thread复制目录，所以这就是我所做的（在我读完之后 {{3 }} ）：

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, System.IOUtils, System.Types;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
TMyThread= class(TThread)
  private
    Fsource, FDest: String;
  protected
  public
    constructor Create(Const Source, Dest: string);
    destructor Destroy; override;
    procedure Execute(); override;
  published
end;
var
  Form1: TForm1;
  MT: TMyThread;
implementation

{$R *.dfm}

{ TMyThread }

constructor TMyThread.Create(const Source, Dest: string);
begin
  Fsource:= Source;
  FDest:= Dest;
end;

destructor TMyThread.Destroy;
begin

  inherited;
end;

procedure TMyThread.Execute;
var Dir: TDirectory;
begin
  inherited;
  try
    Dir.Copy(Fsource, FDest);
  except on E: Exception do
    ShowMessage(E.Message);
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
MT := TMyThread.Create('SourceFolder', 'DestinationFolder');
try
  MT.Execute;
finally
  MT.Free;
end;
end;

end.

当我点击Button1时，收到以下错误消息：

  

无法在正在运行或已挂起的线程上调用Start

这里有什么问题？我对线程知之甚少，我甚至尝试过：

MT := TMyThread.Create('SourceFolder', 'DestinationFolder');

Answer 1

感谢所有人帮助提供有用的评论：

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, System.IOUtils, System.Types;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
TMyThread= class(TThread)
  private
    Fsource, FDest: String;
  protected
  public
    constructor Create(Const Source, Dest: string);
    destructor Destroy; override;
    procedure Execute(); override;
  published
end;
var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TMyThread }

constructor TMyThread.Create(const Source, Dest: string);
begin
  inherited Create;
  Fsource:= Source;
  FDest:= Dest;
  Self.FreeOnTerminate := True;
end;

destructor TMyThread.Destroy;
begin
  inherited;
end;

procedure TMyThread.Execute;
begin
  try
    TDirectory.Copy(Fsource, FDest);
  except on E: Exception do
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var MT: TMyThread;
begin
MT := TMyThread.Create('Source', 'Destination');
end;

end.