Parse platform 使用解析android登录Facebook时出现空指针异常

loginreadsubmission上发生空指针异常

public void btnfacebook(View view) {
     ParseFacebookUtils.logInWithReadPermissionsInBackground(this, permission, new LogInCallback() {
        @Override
        public void done(ParseUser user, ParseException err) {
            if (user == null) {

            } else if (user.isNew()) {

            } else {
                Toaster.show(getApplicationContext(),"YES");
            }
        }
      });
  }

权限变量：

List<String> permission = permission = Arrays.asList("email");

List permission=permission=Arrays.asList（“电子邮件”）；

请帮忙