Question

delphi，窗口显示

有form1(unit1),form2(unit2),form3(unit3) ;在form1和form2中均有一个button按钮
我的目的是，form1中点击button显示form2，然后再form2在点击button显示form3.
代码：
unit Unit1;

interface

uses
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;

var
Form1: TForm1;

implementation
uses unit2,unit3;

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
form2.show;
end;

end.

unit Unit2;

interface

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

type
TForm2 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form2: TForm2;

implementation
uses unit3;

{$R *.dfm}

procedure TForm2.Button1Click(Sender: TObject);
begin
form3.show;
end;

end.

运行后，form1中点击button可以显示form2，但是在form2中点击button，出现access violation错误。
我在form3.show前面加了句Form3:=Tform3.Create(self);的话，在form2中点击button可以显示form3。但是，我是先建好form3，保存为unit3，然后再unit2中 uses unit3 调用的啊，应该不用添加这句。 我问的是不是很无厘头啊！

Answer 1

unit Unit1;

interface

uses
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;

var
Form1: TForm1;

implementation

uses unit2;

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
Form2.Show;
end;

end.

unit Unit2;

interface

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

type
TForm2 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form2: TForm2;

implementation
uses unit3;

{$R *.dfm}

procedure TForm2.Button1Click(Sender: TObject);
begin
Form3.Show;
end;

end.
我这样运行是没问题的

追问

你的意思是，跟我代码一样，你是可以运行的？

Answer 2

关键在这里。
Application.Initialize;
Application.CreateForm(TForm1, Form1);
Application.CreateForm(TForm2, Form2);
Application.CreateForm(TForm3, Form3);
Application.Run;