item的靠左的2種寫法：
1.
public ViewHolder onCreateViewHolder(ViewGroup parent, intviewType) {
View view = View.inflate(mActivity,R.layout.item_expand_recylerview, null);
ViewHolder vh =newViewHolder(view);
return vh;
}
2.View view = LinearLayout.inflate(mActivity,R.layout.item_expand_recylerview, null);
3.item居中的寫法旭愧，要把parent 傳進(jìn)去
View view = LayoutInflater.from(mActivity).inflate( R.layout.item_expand_recylerview,parent,false);
