碎片，RecyclerView:未连接适配器;跳过布局

Question

我正在使用Fragment来查看RecyclerView。但我总是收到这个错误

E/RecyclerView：未连接适配器；跳过布局

我已经为我的回收视图创建了一个适配器，但布局不显示。php后端运行良好。有人能帮忙吗。这是我的片段和适配器的代码

Tips.java

public class Tips extends Fragment {
Configuration config = new Configuration();
String HttpUrl = config.viewtips_url;
List<TipModel> tipList;
RecyclerView recyclerView;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_tips, container, false);
recyclerView = view.findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
tipList = new ArrayList<>();
loadTips();
return view;
}
private void loadTips() {
StringRequest stringRequest = new StringRequest(Request.Method.GET, HttpUrl,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
JSONArray jsonArray = new JSONArray(response);
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObject = jsonArray.getJSONObject(i);
tipList.add(new TipModel(
jsonObject.getInt("id"),
jsonObject.getString("tip")
));
}
TipAdapter tipAdapter = new TipAdapter(getActivity(), tipList);
recyclerView.setAdapter(tipAdapter);
} catch (JSONException e) {
e.printStackTrace();
}
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
Volley.newRequestQueue(getActivity()).add(stringRequest);
}

TipAdapter.java

public class TipAdapter extends RecyclerView.Adapter<TipAdapter.TipViewHolder> {
private Context context;
private List<TipModel> tipList;
public TipAdapter(Context context, List<TipModel> tipList) {
this.context = context;
this.tipList = tipList;
}
@Override
public TipViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(context);
View view = inflater.inflate(R.layout.itemlayout, null);
return new TipViewHolder(view);
}
@Override
public void onBindViewHolder(TipViewHolder holder, int position) {
TipModel tipModel = tipList.get(position);

holder.textViewTip.setText(tipModel.getTip());
}
@Override
public int getItemCount() {
return tipList.size();
}
class TipViewHolder extends RecyclerView.ViewHolder {
TextView textViewTip;
public TipViewHolder(View view) {
super(view);
textViewTip = view.findViewById(R.id.textViewTip);
}
}

Answer 1

之所以会发生这种情况，是因为RecyclerView在对创建的视图调度布局时需要一个适配器，所以如果在创建视图时没有适配器也没关系，它只会跳过布局部分。

如果你担心这个错误，那么你可以在创建视图时设置一个空适配器：

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_tips, container, false);
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
recyclerView = view.findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
tipList = new ArrayList<>();
recyclerView.setAdapter(new TipAdapter(getActivity(), tipList));
}

然后在响应回调中调整您的代码：

@Override
public void onResponse(String response) {
// Instead of setting adapter here...
// TipAdapter tipAdapter = new TipAdapter(getActivity(), tipList);
// recyclerView.setAdapter(tipAdapter);
// Just notify the adapter that tipList has changed.
recyclerView.getAdapter().notifyDataSetChanged();
// ...
}

Answer 2

TipList是适配器的数据存储，它属于适配器，而不属于Fragment

我已经编辑了你的代码(没有访问Android Studio的权限，在文本编辑器中进行，请检查语法错误(

碎片

public class Tips extends Fragment {
Configuration config = new Configuration();
String HttpUrl = config.viewtips_url;
RecyclerView recyclerView;
TipAdapter tipAdapter;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Initialize the Tip Adapter
tipAdapter = new TipAdapter(getActivity());
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_tips, container, false);
recyclerView = view.findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
// Assign the Adapter to recyclerView
recyclerView.setAdapter(tipAdapter);

return view;
}
private void loadTips() {
StringRequest stringRequest = new StringRequest(Request.Method.GET, HttpUrl,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
JSONArray jsonArray = new JSONArray(response);
// Create a new TipList
List<TipModel> tipList = new ArrayList<>();

for (int i = 0; i < jsonArray.length(); i++) {

JSONObject jsonObject = jsonArray.getJSONObject(i);
tipList.add(new TipModel(
jsonObject.getInt("id"),
jsonObject.getString("tip")
));
}

tipAdapter.updateWith(tipList)

} catch (JSONException e) {
e.printStackTrace();
}
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
Volley.newRequestQueue(getActivity()).add(stringRequest);
}

Tip适配器

public class TipAdapter extends RecyclerView.Adapter<TipAdapter.TipViewHolder> {
private Context context;
private List<TipModel> tipList = new ArrayList<>();
public TipAdapter(Context context) {
this.context = context;
}
@Override
public TipViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(context);
View view = inflater.inflate(R.layout.itemlayout, null);
return new TipViewHolder(view);
}
@Override
public void onBindViewHolder(TipViewHolder holder, int position) {
TipModel tipModel = tipList.get(position);

holder.textViewTip.setText(tipModel.getTip());
}
@Override
public int getItemCount() {
return tipList.size();
}
class TipViewHolder extends RecyclerView.ViewHolder {
TextView textViewTip;
public TipViewHolder(View view) {
super(view);
textViewTip = view.findViewById(R.id.textViewTip);
}
}
public updateWith(List<TipModel> tipList) {
this.tipList = tipList;
notifyDataSetChanged();
}

Answer 3

当我在片段中膨胀回收器视图时遇到类似问题时，我就是这样做的。这个代码非常适合我：

附言-这是我在应用程序中使用的代码补丁。很抱歉给您带来不便。

首先，在显示片段的onCreateView((中：

public View onCreateView(@NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.fragment_home, container, false);
Firebase.setAndroidContext(getActivity());
((Home_Drawer) getActivity())
.setActionBarTitle("Home");
recyclerView = (RecyclerView) root.findViewById(R.id.recycler_view_home_frag);
progressBar = (ProgressBar) root.findViewById(R.id.mainPageProgressBar);
//        Log.i("inside", "rv initiated" +mLayoutManager.toString());
// Assign activity this to progress dialog.
progressDialog = new ProgressDialog(getActivity());
// Setting up message in Progress dialog.
progressDialog.setMessage("Loading Images From Firebase.");
// Showing progress dialog.
progressDialog.show();
// The path is already defined in MainActivity.
databaseReference = FirebaseDatabase.getInstance().getReference().child("productDisplay");
Log.i("inside", databaseReference.toString());
return root;
}

然后，我们调用onStart((。这是因为回收器视图通常不会膨胀，因此需要在onCreateView((中设置适配器。

@Override
public void onStart() {
super.onStart();
FirebaseRecyclerOptions<DisplayItemsModel> item_info =
new FirebaseRecyclerOptions.Builder<DisplayItemsModel>()
.setQuery(databaseReference, DisplayItemsModel.class)
.build();
final FirebaseRecyclerAdapter<DisplayItemsModel, ViewHolder> info_adapter =
new FirebaseRecyclerAdapter<DisplayItemsModel, ViewHolder>(item_info) {
@Override
protected void onBindViewHolder(final ViewHolder holder, final int position, final DisplayItemsModel model) {
mContext = getContext();
final DatabaseReference dref = getRef(position).getRef();
Log.i("dref", dref.toString());
// Adding Add Value Event Listener to databaseReference.
dref.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(final DataSnapshot snapshot) {
holder.item_name_single_card.setText(snapshot.child("name").getValue().toString());
holder.price_single_card.setText(snapshot.child("price").getValue().toString());
String image_url = snapshot.child("image").getValue().toString();
Picasso.get().load(image_url).into(holder.thumbnail);
// Continue with your code.

这对我来说效果很好。希望它能解决你的问题。