RecyclerView android:layout_width="match_parent"无效

使用RecyclerView 时，在xml文件中设置宽度match_parent无效，发现在Adapter中要如下填充view（注释掉的填充方式会导致match_parent无效）

/**
     * 创建新View，被LayoutManager所调用
     */
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
//        View view = View.inflate(parent.getContext(), R.layout.item_fra_main2, null);
        View view = mInflater.from(mContext).inflate(R.layout.item_fra_main2, parent, false);
        ViewHolder holder = new ViewHolder(view);
        return holder;
    }