unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Label1: TLabel;
    Button3: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }

      procedure SimulateError(Button : TObject);
      procedure ToDo(Button : TObject);
  end;

var
  Form1: TForm1;

implementation

uses ExceptionClass;

{$R *.dfm}

procedure TForm1.SimulateError(Button : TObject);
begin
    if Button = Button1 then
        raise EFileNotFound.Create('File Not Found')
    else if Button = Button2 then
        raise EFileFormatErr.Create('File Format Error')
    else // Button = Button3
        raise Exception.Create('Unknonw Error');
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
    ToDo(Sender);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
    ToDo(Sender);
end;

procedure TForm1.ToDo(Button : TObject);
begin
    try
        SimulateError(Button)
    except
        on E : EFileOpenFailed do
            E.Warning();
        on E : Exception do
            ShowMessage(E.Message);
    end;
end;

procedure TForm1.Button3Click(Sender: TObject);
var
    AStream : TMemoryStream;
begin
    AStream := TMemoryStream.Create();

    try
        SimulateError(Sender);
    finally
        AStream.Free();
    end;
end;

end.