关于多线程控制的一些问题

unit Unit1;

interface

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

type
  TMyThread = class(TThread)
  protected
    procedure Execute; override;
    procedure SetValue;
  public
end;

type
  TMyThread2 = class(TThread)
  protected
    procedure Execute; override;
  public
end;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    Button5: TButton;
    Button6: TButton;
    Button7: TButton;
    Button8: TButton;
    Edit2: TEdit;
    Edit1: TEdit;
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button5Click(Sender: TObject);
    procedure Button6Click(Sender: TObject);
    procedure Button7Click(Sender: TObject);
    procedure Button8Click(Sender: TObject);
  private
    { Private declarations }
     MyThread: TMyThread;
     MyThread2: TMyThread2;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TMyThread.Execute;
begin
  FreeOnTerminate := True;
  Synchronize(SetValue);
end;

procedure TMyThread.SetValue;
var
  i: Integer;
begin
  for i := 0 to 100000 do
  begin
    Application.ProcessMessages;
    if self.Terminated then Break;
    form1.Edit1.Text := IntToStr(i);
  end;
end;

procedure TMyThread2.Execute;
var
  i: Integer;
begin
  FreeOnTerminate := True;
  for i := 0 to 100000 do
  begin
    Application.ProcessMessages;
    if self.Terminated then Break;
    form1.Edit2.Text := IntToStr(i);
  end;
end;


//开始线程
procedure TForm1.Button1Click(Sender: TObject);
begin
  MyThread := TMyThread.Create(false);
end;

//暂停线程
procedure TForm1.Button2Click(Sender: TObject);
begin
  MyThread.Suspend;
end;

//终止线程
procedure TForm1.Button3Click(Sender: TObject);
begin
  MyThread.Terminate;
end;

//继续执行线程
procedure TForm1.Button4Click(Sender: TObject);
begin
  MyThread.Resume;
end;

procedure TForm1.Button5Click(Sender: TObject);
begin
  MyThread2 := TMyThread2.Create(false);
end;

procedure TForm1.Button6Click(Sender: TObject);
begin
  MyThread2.Suspend;
end;

procedure TForm1.Button7Click(Sender: TObject);
begin
  MyThread2.Terminate;
end;

procedure TForm1.Button8Click(Sender: TObject);
begin
  MyThread2.Resume;
end;

end.