procedure TForm1.Button1Click(Sender: TObject);
var
  aFile:Jfile;
  Intent:JIntent;
begin

  aFile:=TJfile.JavaClass.init(stringtojstring(GetSharedDownloadsDir),stringtojstring('APP.apk'));
  Intent := TJIntent.Create ;
  Intent.setAction(TJIntent.JavaClass.ACTION_VIEW);
  Intent.addFlags(TJIntent.JavaClass.FLAG_ACTIVITY_NEW_TASK);
  Intent.setDataAndType(TJnet_Uri.JavaClass.fromFile(aFile),StringToJString('application/vnd.android.package-archive'));
  SharedActivityContext.startActivity(Intent);
end;

  dpath :=  'file://'+dpath;
  jpath :=   StringTojString( dpath) ;
  Intent.setDataAndType(TJnet_Uri.JavaClass.parse(jpath) , StringTojString('application/vnd.Android.package-archive'));