java - fragment 中的空指针异常(初始化 ListView )

Question

这是我尝试在 Fragment 中显示列表的代码，截至目前一直报告 NullPointerException每当它尝试初始化 ListView :

public class PortfolioFragment extends ListFragment {

ListView l;
ArrayAdapter<String> adapter;
List<String> list;

public PortfolioFragment() {
    // Required empty public constructor
}

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

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    list = MainActivity.globalArrayTest;
    l = (ListView) getView().findViewById(android.R.id.list);
    adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, list);
    l.setAdapter(adapter);

    return inflater.inflate(R.layout.fragment_portfolio, container, false);

}

我在这一行收到错误:

l = (ListView) getView().findViewById(android.R.id.list);

Answer 1

更改为

View v = inflater.inflate(R.layout.fragment_portfolio, container, false);
l = (ListView) v.findViewById(android.R.id.list);
return v; 

您应该在 xml 中包含以下内容

<ListView android:id="@android:id/list"

或者重写onActivityCreated并使用getListView()

您也可以使用下面的内容，因为黑带评论说这比上面的更好。

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onActivityCreated(savedInstanceState);
            l = getListView(); // since you extend ListFragment
}