使用Parse android在Facebook登录时出现空指针异常

Question

在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");

请帮助!!!