unit Unit1;interfaceuses  System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,  FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs,  FMX.Controls.Presentation, FMX.StdCtrls;type  TForm1 = class(TForm)    Button1: TButton;    Button2: TButton;    Button3: TButton;    Label1: TLabel;    Button4: TButton;    Button5: TButton;    Button6: TButton;    procedure Button1Click(Sender: TObject);    procedure Button2Click(Sender: TObject);    procedure Button3Click(Sender: TObject);    procedure FormKeyUp(Sender: TObject; var Key: Word; var KeyChar: Char;      Shift: TShiftState);    procedure Button4Click(Sender: TObject);    procedure Button6Click(Sender: TObject);    procedure Button5Click(Sender: TObject);  private    { Private declarations }  public    { Public declarations }  end;var  Form1: TForm1;implementationusesFMX.Platform.Android,FMX.Helpers.Android,Androidapi.JNI.Net,Androidapi.JNI.GraphicsContentViewText,Androidapi.JNI.JavaTypes,Androidapi.Helpers,system.IOUtils;{$R *.fmx}{$R *.NmXhdpiPh.fmx ANDROID}{$R *.LgXhdpiPh.fmx ANDROID}{$R *.Macintosh.fmx MACOS}{$R *.XLgXhdpiTb.fmx ANDROID}{$R *.LgXhdpiTb.fmx ANDROID}{$R *.GGlass.fmx ANDROID}procedure TForm1.Button1Click(Sender: TObject);begin  Label1.Text := ‘按返回键将会出现一个对话框！‘;end;procedure TForm1.Button2Click(Sender: TObject);begin  MainActivity.finish; { 退出程序 }end;procedure TForm1.Button3Click(Sender: TObject);begin  {$IFDEF ANDROID}    Application.MainForm.DisposeOf; { 退出程序 }    halt(0);  {$ENDIF}end;procedure TForm1.Button4Click(Sender: TObject);var  Intent: JIntent;begin  Intent := TJIntent.JavaClass.init(TJIntent.JavaClass.ACTION_MAIN);  Intent.addCategory(TJIntent.JavaClass.CATEGORY_HOME);  Intent.setFlags(TJIntent.JavaClass.FLAG_ACTIVITY_NEW_TASK);  SharedActivityContext.startActivity(Intent);end;procedure TForm1.Button5Click(Sender: TObject);begin  Application.Terminate;end;procedure TForm1.Button6Click(Sender: TObject);begin  Close;end;//此代码报错，不可用，原因不明。procedure TForm1.FormKeyUp(Sender: TObject; var Key: Word; var KeyChar: Char;  Shift: TShiftState);begin  if Key = vkHardwareBack then//如果按下物理返回键  begin    Label1.Text := ‘1‘;    if MessageDlg(‘确认退出吗？‘, TMsgDlgType.mtConfirmation,    [TMsgDlgBtn.mbOK, TMsgDlgBtn.mbCancel], -1) = mrOK then      MainActivity.finish; { 退出程序 }    Key := 0;//必须的，不然按否也会退出    Exit;  end;end;end.