android新手想多联系下fragment的使用,可在listview.setAdapter时遇到了如下问题:
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
at com.example.sms.InsertFragment.onCreate(InsertFragment.java:73)
以下是代码
private ListView insert_choose_listView;
ArrayList<HashMap<String, String>> listItem;
MyAdapter myAdapter;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
listItem = new ArrayList<HashMap<String,String>>();
HashMap<String, String> map = new HashMap<String, String>();
map.put("Insert"," Insert Teacher");listItem.add(map);
map.put("Insert"," Insert Student");listItem.add(map);
map.put("Insert"," Insert Course");listItem.add(map);
myAdapter=new MyAdapter(this.getActivity());
insert_choose_listView.setAdapter(myAdapter);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view=inflater.inflate(R.layout.fragment_insert, container, false);
insert_choose_listView=(ListView)view.findViewById(R.id.insert_choose_listview);
return view;
}
private class MyAdapter extends BaseAdapter {
private LayoutInflater mInflater;//得到一个LayoutInfalter对象用来导入布局
public MyAdapter (Context context){
this.mInflater= LayoutInflater.from(context);
}
public int getCount(){
return listItem.size();
}
@Override
public Object getItem(int position) {
return null;
}
@Override
public long getItemId(int position) {
return 0;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
InsertFragment.MyAdapter.ViewHolder holder;
//观察convertView随ListView滚动情况
Log.v("MyListViewBase", "getView " + position + " " + convertView);
if (convertView == null) {
convertView = mInflater.inflate(R.layout.flistviewlayout,null);
holder = new InsertFragment.MyAdapter.ViewHolder();
/**得到各个控件的对象*/
holder.title = (TextView) convertView.findViewById(R.id.ftext);
convertView.setTag(holder);//绑定ViewHolder对象
}
else{
holder = (InsertFragment.MyAdapter.ViewHolder)convertView.getTag();//取出ViewHolder对象
}
/**设置TextView显示的内容,即我们存放在动态数组中的数据*/
holder.title.setText(listItem.get(position).get("Insert").toString());
return convertView;
}
/**存放控件*/
public final class ViewHolder{
public TextView title;
}
报错的73行是insert_choose_listView.setAdapter(myAdapter);这句
我在Activity中这样加入ListView是不会报错的可是放到Fragment中就成了空的
求解答