片段内的 DialogFragment 内的 RecyclerView

Question

我正在尝试在 Fragment 内的 DialogFragment 内膨胀 RecyclerView。我按照指南正常制作了 RecyclerView Adapter。

但是我收到这个错误java.lang.NullPointerException: Attempt to invoke virtual method 'voidandroid.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)' on a null object reference

在线

recyclerView.setLayoutManager(manager);

完整代码如下

public class AlertFragment extends DialogFragment {
RecyclerView recyclerView;
RecyclerView.Adapter adapter2;
RecyclerView.LayoutManager manager;

ArrayList<String> goalname = new ArrayList<String>();
 ArrayList<String> goalcategory = new ArrayList<String>();

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.fragment_alert, container, false);
    goalname.add("Running");
    goalcategory.add("Physical");
    goalname.add("Yoga");
    goalcategory.add("Physical");
    goalname.add("Gym");
    goalcategory.add("Physical");
    goalname.add("Meditation");
    goalcategory.add("Mental");
    goalname.add("Puzzle Solving");
    goalcategory.add("Habits");
    manager = new LinearLayoutManager(getActivity());
    recyclerView = (RecyclerView) getActivity().findViewById(R.id.bookhistory);
    recyclerView.setLayoutManager(manager);


    adapter2 = new GoalListAdapter(goalname, goalcategory,getActivity());
    recyclerView.setAdapter(adapter2);
    adapter2.notifyDataSetChanged();
    return v;
}}

Answer 1

您的问题与此行有关：

    recyclerView = (RecyclerView) getActivity().findViewById(R.id.bookhistory);

您真的想从您在此行的片段中膨胀的视图中获取 RecyclerView

    View v = inflater.inflate(R.layout.fragment_alert, container, false);

所以要解决这个问题，请将我提到的第一行代码更改为

    recyclerView = (RecyclerView) v.findViewById(R.id.bookhistory);

这是假设 DialogFragment 包含 bookhistory

Answer 2

显然它会崩溃，因为它没有找到回收器视图实例。

只需替换这一行：

  recyclerView = (RecyclerView) getActivity().findViewById(R.id.bookhistory);

搭配：

 recyclerView = (RecyclerView) v.findViewById(R.id.bookhistory);

现在它会为你工作。

片段内的 DialogFragment 内的 RecyclerView

RecyclerView inside DialogFragment inside Fragment

java

android

android-fragments

android-dialogfragment

android-recyclerview