Thread-demo


            For those of you who haven't been into Thread-programming, maybe this simple
demo would be of interest:
The program creates ten parallell threads, each thread is associated with a 
progressbar, which is updated randomly. When the Thread is done it's reported to a memo.
You can download the pas- and dfm-file here: 
unit Unit1;
interface
uses
 Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
 StdCtrls, ComCtrls;
type
 TProgressThread = class(TThread)
 private
 fRandomNo: Integer;
 fThreadNo: Integer;
 fProgress: Integer;
 fDone: Boolean;
 protected
 procedure Execute; override;
 procedure ShowProgress;
 end;
 TForm1 = class(TForm)
 Button1: TButton;
 ProgressBar1: TProgressBar;
 ProgressBar2: TProgressBar;
 ProgressBar3: TProgressBar;
 ProgressBar4: TProgressBar;
 ProgressBar5: TProgressBar;
 ProgressBar6: TProgressBar;
 ProgressBar7: TProgressBar;
 ProgressBar8: TProgressBar;
 ProgressBar9: TProgressBar;
 ProgressBar10: TProgressBar;
 Memo1: TMemo;
 procedure Button1Click(Sender: TObject);
 private
 ProgressThread: TProgressThread;
 { Private declarations }
 public
 { Public declarations }
 end;
var
 Form1: TForm1;
implementation
{$R *.DFM}
procedure TForm1.Button1Click(Sender: TObject);
var n: Integer;
begin
 Randomize;
 Memo1.Clear;
 // Create 10 Threads, give them a random no. and start them
 for n:= 1 to 10 do
 begin
 ProgressThread:= TProgressThread.Create(true);
 ProgressThread.FreeOnTerminate:= true;
 ProgressThread.fThreadNo:= n;
 ProgressThread.fRandomNo:= Random(100);
 ProgressThread.FProgress:= 0;
 ProgressThread.fDone:= false;
 // Start the Thread
 ProgressThread.Resume;
 end;
end;
{ TProgressThread }
procedure TProgressThread.Execute;
begin
 repeat
 
 // Compare Threads RandomNo with a RandomNo generated each time looped
 // One chance of 100 000 that fProgress will be increased
 if fRandomNo = Random(100000) then
 begin
 if fProgress < 100 then
 begin
 Inc(fProgress);
 if fProgress = 100 then fDone:= true;
 
 // Update ProgressBar
 Synchronize(ShowProgress);
 end;
 end;
 until fDone;
end;
procedure TProgressThread.ShowProgress;
begin
 // Update the ProgressBar associated with the Thread
 case fThreadNo of
 1: Form1.ProgressBar1.Position:= fProgress;
 2: Form1.ProgressBar2.Position:= fProgress;
 3: Form1.ProgressBar3.Position:= fProgress;
 4: Form1.ProgressBar4.Position:= fProgress;
 5: Form1.ProgressBar5.Position:= fProgress;
 6: Form1.ProgressBar6.Position:= fProgress;
 7: Form1.ProgressBar7.Position:= fProgress;
 8: Form1.ProgressBar8.Position:= fProgress;
 9: Form1.ProgressBar9.Position:= fProgress;
 10: Form1.ProgressBar10.Position:= fProgress;
 end;
 // Write to Memo if Done
 if fDone then
 Form1.Memo1.Lines.Add('Thread No: ' + IntToStr(fThreadNo) +
 ' terminated.');
end;
end.
Examples Delphi
