线程的小问题

Question

unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
type
  TTestThread=class(TThread)
    procedure Execute;override;
  end;
var
  Form1: TForm1;implementation{$R *.dfm}
procedure TTestThread.Execute;
begin
  FreeOnTerminate:=True;
  ShowMessage('已经激活');
end;
procedure TForm1.Button1Click(Sender: TObject);
var
  Test:TTestThread;
begin
  Test:=TTestThread.Create(false);
end;end.单击按钮，有时候会弹出对话框，有时候搞什么乱七八糟的东西，为什么？

Answer 1

  ShowMessage('已经激活');
ShowMessage在线程中直接用是不安全的。正确的做法是线程需要ShowMessage时，用SendMessage发送消息给主窗口，然后在主窗口的消息处理函数中ShowMessage

Answer 2

是线程同步的问题，对界面的操作要放在主界面！
type
  TTestThread=class(TThread)
    procedure Execute;override;
    procedure a;
  end;
var
  Form1: TForm1;implementation{$R *.dfm}
procedure TTestThread.a;
begin
  ShowMessage('已经激活');
end;
procedure TTestThread.Execute;
begin
  inherited;
  FreeOnTerminate:=True;
  Synchronize(a)
end;

Answer 3

http://topic.csdn.net/u/20120410/19/86683e59-2c50-482f-8ade-776079b74b0e.html?seed=247564147&r=78197496#r_78197496