请设计并实现一个日期类，实现下面的目标：

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Edit1: TEdit;
    Edit2: TEdit;
    Edit3: TEdit;
    Edit4: TEdit;
    Edit5: TEdit;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Label4: TLabel;
    Label5: TLabel;
    Button3: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);

  private
    { Private declarations }
  public
    { Public declarations }
  end;

type
   tstudent=class
  private
      id:integer;
      name:string;
      sex:string;
      yingyu,delphi0:double;
  public
      procedure setid(xuehao:integer);
      procedure setname(xingming:string);
      procedure setsex(xingbie:string);
      procedure setlesson(english:double);
      procedure setlesson1(delphi:double);

end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure tstudent.setid(xuehao:integer);
begin
   id:=xuehao;
end;



procedure tstudent.setname(xingming:string);
begin
  name:=xingming;
end;



procedure tstudent.setsex(xingbie:string);
begin
  sex:=xingbie;
end;



procedure tstudent.setlesson(english:double);
begin
  yingyu:=english;
end;

procedure tstudent.setlesson1(delphi:double);
begin
  delphi0:=delphi;
end;


procedure TForm1.Button1Click(Sender: TObject);
var
   stu1:tstudent;
begin
   stu1:=tstudent.Create();
   stu1.setid(12);
   stu1.setname('小明');
   stu1.setsex('男');
   stu1.setlesson(85);
   stu1.setlesson1(90);
   edit1.Text:=inttostr(stu1.id);
   edit2.Text:=stu1.name;
   edit3.Text:=stu1.sex;
   edit4.Text:=floattostr(stu1.yingyu);
   edit5.Text:=floattostr(stu1.delphi0);
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  close;
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  stu2:tstudent;
begin
  stu2:=tstudent.Create();
  stu2.setid(28);
  stu2.setsex('女');
  stu2.setname('小萌');
  stu2.setlesson(90);
  stu2.setlesson1(99);
  edit1.Text:=inttostr(stu2.id);
  edit2.Text:=stu2.name;
  edit3.Text:=stu2.sex;
  edit4.Text:=floattostr(stu2.yingyu);
  edit5.Text:=floattostr(stu2.delphi0);
end;

end.