我按照教程嘗試編寫自定義Adapter，繼承BaseAdapter，在重寫getView方法時，使用了
convertView?=?inflater.inflate(R.layout.lv_test_list,null);?然而在運行時就報錯了，顯示?java.lang.NullPointerException:?Attempt?to?invoke?virtual?method?'android.view.View?android.view.LayoutInflater.inflate(int,?android.view.ViewGroup)'?on?a?null?object?reference。

但是，視頻教程就是這么寫的~~如下圖所示，第70行代碼。請問我的問題出在哪里？我該如何修改？?

我的代碼如下：

public?class?ListAdapter?extends?BaseAdapter?{
?
????private?List<ListAdapterItem>?items;
????LayoutInflater?inflater;
????public?ListAdapter(Context?context,List<ListAdapterItem>?source){
????????items?=?source;
????????inflater.from(context);
????}
?
@Override
????public?View?getView(int?position,?View?convertView,?ViewGroup?parent)?{
????????ViewHolder?vh;
????????if(convertView?==?null){
????????????convertView?=?inflater.inflate(R.layout.lv_test_list,null);
????????????ImageView?img??=?(ImageView)?convertView.findViewById(R.id.img_icon);
????????????TextView?tv_title?=?(TextView)?convertView.findViewById(R.id.tv_title);
????????????TextView?tv_content?=?(TextView)?convertView.findViewById(R.id.tv_content);
????????????vh?=?new?ViewHolder();
????????????vh.content?=?tv_content;
????????????vh.title?=?tv_title;
????????????vh.img?=?img;
????????????convertView.setTag(vh);
????????}
????????else{
????????????vh?=?(ViewHolder)?convertView.getTag();
????????}
????????ListAdapterItem?item?=?items.get(position);
????????vh.content.setText(item.str_content);
????????vh.title.setText(item.str_title);
????????vh.img.setImageResource(item.int_img);
????????return?convertView;
????}
?
????class??ViewHolder?{
????????public?ImageView?img;
????????public?TextView?title;
????????public?TextView?content;
????}
}