getScrollX（）返回错误的值，为什么？

Question

recList.getScrollX()行总是返回0，即使用户已经滚动了recList。

protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            final RecyclerView recList = (RecyclerView) findViewById(R.id.userSettingList);

    horizontalScrollView.getViewTreeObserver().addOnScrollChangedListener(new ViewTreeObserver.OnScrollChangedListener() {

                @Override
                public void onScrollChanged() {

                        int scrollX0 = recList.getScrollX(); //always returns 0, why?

                    }
                }
            });
        }