Recyclerview 不调用 onCreateViewHolder

Question

My RecyclerView does not call onCreateViewHolder , onBindViewHolder even MenuViewHolder constructor, therefore nothing appears in RecyclerView . I put logs for debugging, and no log is shown. What might be the problem?

My adapter:

public class MenuAdapter extends RecyclerView.Adapter<MenuAdapter.MenuViewHolder> {
private LayoutInflater inflater;
List<Menu> data = Collections.emptyList();

public MenuAdapter(Context context, List<Menu> data) {
    Log.i("DEBUG", "Constructor");
    inflater = LayoutInflater.from(context);
    Log.i("DEBUG MENU - CONSTRUCTOR", inflater.toString());
    this.data = data;
    for(Menu menu: this.data){
        Log.i("DEBUG MENU - CONSTRUCTOR", menu.menu);
    }
}

@Override
public MenuViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = inflater.inflate(R.layout.row_menu, parent, false);
    MenuViewHolder holder = new MenuViewHolder(view);
    return holder;
}

@Override
public void onBindViewHolder(MenuViewHolder holder, int position) {
    Log.i("DEBUG MENU", "onBindViewHolder");
    Menu current = data.get(position);
    holder.title.setText(current.menu);
}

@Override
public int getItemCount() {
    return 0;
}

class MenuViewHolder extends RecyclerView.ViewHolder {
    TextView title;
    ImageView icon;

    public MenuViewHolder(View itemView) {
        super(itemView);
        title = (TextView) itemView.findViewById(R.id.menuText);
    }
}

My custom row XML:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal" android:layout_width="match_parent"
android:layout_height="match_parent">

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/menuText"
    android:text="Dummy Text"
    android:layout_gravity="center_vertical"
    android:textColor="#222"/>

and my Fragment:

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

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mUserLearnedDrawer = Boolean.valueOf(readFromPreferences(getActivity(), KEY_USER_LEARNED_DRAWER, "false"));
    if (savedInstanceState != null) {
        mFromSavedInstaceState = true;
    }
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment

    View view = inflater.inflate(R.layout.fragment_navigation, container, false);
    RecyclerView recyclerView = (RecyclerView) view.findViewById(R.id.drawer_list);
    MenuAdapter adapter = new MenuAdapter(getActivity(), getData());
    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
    recyclerView.setAdapter(adapter);
    return view;
}

Answer 1

另一个是确保将布局管理器设置为 RecyclerView：

recycler.setLayoutManager(new LinearLayoutManager(this));

Answer 2

Your getItemCount method returns 0 . So RecyclerView never tries to instantiate a view. Make it return something greater than 0 .

for example

@Override
public int getItemCount() {
    return data.size();
}

Answer 3

添加它对我有用后，我忘了添加以下行

recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

Answer 4

Please set layout manager to RecyclerView like below code:

RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view_right);
//set your recycler view adapter here
NavigationAdapter adapter = new NavigationAdapter(this, FragmentDrawer.getData());
recyclerView.setAdapter(adapter);
recyclerView.setLayoutManager(new LinearLayoutManager(this));

Answer 5

I really really hope this helps someone someday. I just spent over an hour on this one going nuts!

I had this:

projects_recycler_view.apply {
            this.layoutManager = linearLayoutManager
            this.adapter = adapter
        }

When I should have had this:

projects_recycler_view.apply {
            this.layoutManager = linearLayoutManager
            this.adapter = projectAdapter
        }

Because I foolishly called my adapter adapter , it was being shadowed by the recycler view's adapter in the apply block! I renamed the adapter to projectAdapter to differentiate it and problem solved!

Answer 6

This does not apply for your particular case. But this might help someone else.

This reason could be careless usage of the following method

recyclerView.setHasFixedSize(true);

If not used with caution, this might cause the onBindView and onCreateViewHolder to not be called at all, with no error in the logs.

Answer 7

For what it's worth, I observed it when I set the recycler view adapter before the adapter was actually initialized. Solution was to make sure recyclerView.setAdapter(adapter) was called with a non-null adapter

Answer 8

也许它对某人有帮助，但是如果您将 RecycleView 的可见性设置为 GONE，则根本不会调用适配器方法......我花了一些时间来弄清楚。

Answer 9

Setting the height of the TextView in the custom.xml or RecyclerView . If height is wrap-content , the RecyclerView will not be visible.

Answer 10

This happened when my RecyclerView was inside a ScrollView and I was using Android Support Library 23.0. To fix, I updated to Android Support Library 23.2:

In build.gradle:

dependencies {
    ...
    compile 'com.android.support:appcompat-v7:23.2.+'
    compile 'com.android.support:cardview-v7:23.2.+'
}

Answer 11

I had the same problem, because I was using android.support.constraint.ConstraintLayout in layout resource. Changing to FrameLayout helped.

Answer 12

Add this to Your Adapter Class

 @Override
    public int getItemCount() {
        return mDataset.size();
    } 

Answer 13

Other option is if you send this list objetc using get,verify if you have correct reference,for example

private list<objetc> listObjetc;
//Incorrect
public void setListObjetcs(list<objetc> listObjetc){
  listObjetc = listObjetc;
}

//Correct
public void setListObjetcs(list<objetc> listObjetc){
  this.listObjetc = listObjetc;
}

Answer 14

I struggled with this issue for many hours. I was using a fragment. And the issue was not returning the view . Below is my code:

ProductGridBinding binding = DataBindingUtil.inflate( inflater, R.layout.product_grid, container, false);



    mLinearLayoutManager = new LinearLayoutManager(getActivity());
    mLinearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);

    binding.rvNumbers.setHasFixedSize(true);
    binding.rvNumbers.setLayoutManager(mLinearLayoutManager);
    binding.rvNumbers.setAdapter(adapter);


    View view = binding.getRoot();


    return view;

Answer 15

See my answer if you are using android data binding library - Make sure you are setting layout for recyclerview and item count must be greater than 0

 @BindingAdapter({"entries", "layout"})
    public static void setEntries(RecyclerView view, ArrayList<LoginResponse.User> listOfUsers, int layoutId) {
        if (view.getAdapter() == null) {
            view.setLayoutManager(new LinearLayoutManager(view.getContext()));
            SingleLayoutAdapter adapter = new SingleLayoutAdapter(layoutId) {
                @Override
                protected Object getObjForPosition(int position) {

                    return listOfUsers.get(position);
                }

                @Override
                public int getItemCount() {
                    return listOfUsers.size();
                }
            };
            view.setAdapter(adapter);
        }
    }

Happy coding :-)

Answer 16

If you put wrap_content as height of your list as well as the height of your item list, nothing will show up and none of your recyclerView functions will be called. Fix the height of the item or put match_parent for the list height. That solved my problem.

Answer 17

You forget this line in the xml app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"

or

    app:layoutManager="androidx.recyclerview.widget.GridLayoutManager"

Answer 18

In my case I set the ID of my RecyclerView to "recyclerView". It seems that this ID was already defined somewhere, because when I changed that to different ID, the methods from the adapter were called properly.

Answer 19

如果使用自定义适配器，请不要忘记将 ItemCount 设置为您的集合的大小。

Answer 20

In my case, my list size was 0 and it was not calling the onCreateViewHolder method. I needed to display a message at center for the empty list as a placeholder so I did it like this and it worked like charm. Answer by @Konstantin Burov helped.

  @Override
public int getItemCount() {
    if (contactList.size() == 0) {
        return 1;
    } else {
        return contactList.size();
    }
}

Answer 21

My encouter was the onBindViewHolder( holder , position) overrided method of the RecyclerView.adaptor not being called. Method onCreateViewHolder was called, getItemCount was called. If you read the specs for Recyclerview Adapter, you will learn that if you have overrided onBindViewHolder( holder, position, List payloads) will be called in favour. So please be careful.

Answer 22

我的错误是在 Fragment onCreateView 中夸大了错误的视图。

Answer 23

go to your xml. And change your layout to wrap content. The one element is hiding the next one, so the methods are not working!

Answer 24

You can add this in your XML widget RecyclerView

 app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"

or manually

reyclerview.setLayoutManager(new LinearLayoutManager(ActivityName.this));

Answer 25

Please do the following thing

@Override
public int getItemCount() {
    return data.size();
}

Answer 26

In my case after changing Activity to use ViewModel and DataBinding, I had forgotten to remove setContentView method calling from onCreate method. By removing it my problem solved.

Answer 27

For me, it was because the setHasStableIds(true); method was set. Remove that and it will work

Answer 28

recyclerView.setAdapter(adapter); called The recyclerView list is populated by calling the method.

Answer 29

Make sure your XML and Koltin/Java code match. In my case, I had a problem with the ViewHolder since I had written:

var txt: AppCompatTextView = itemView.findViewById(R.id.txt)

But since my XML code is:

<TextView
        android:id="@+id/txt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        .../>

I had to change the privious row into:

var txt: TextView = itemView.findViewById(R.id.txt)

In addition, I also had to remove:

recyclerView.setHasFixedSize(true);

I hope this can help you :)

Answer 30

In my case , I was missing calling notifyDataSetChanged() after setting list in adapter.

public void setUserList(List<UserList> userList) {
      this.userList = userList;
        notifyDataSetChanged();
}

Answer 31

In my case I miss to set the orientation in my LinearLayout.

After adding orientation issue fixed.

 android:orientation="vertical"

Answer 32

我的问题是 RecyclerView 的layout_height和layout_width设置为0dp 。

Answer 33

I had an issue because i setup the layout by myself and have put

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/band_recycler_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />
</androidx.recyclerview.widget.RecyclerView>

and

<androidx.recyclerview.widget.RecyclerView
        android:id="@+id/band_recycler_view"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:textAlignment="center">

resolved my issue

Answer 34

Not the case in the main post, but it may come in handy for someone. If you set setHasStableIds(true); , override getItemId(position) is the adapter.

Answer 35

In my case I was returning null from onCreateView of fragment.

override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        binding=DataBindingUtil.inflate(inflater,R.layout.fragment_add_budget,container,false)
        setRecyclerView()
        return null// that was the culprit
    }

Answer 36

My answer do not applies to yours but may apply to someones else cause I had the same problem you are facing.

So I actually did:

RecyclerView rv = new RecyclerView(this);

instead of

RecyclerView rv = findViewById(R.id.Recycler);

So make sure to take a note on that.

Answer 37

For those having this problem in Kotlin, use this code instead:

recycler.layoutManager = LinearLayoutManager(context)

Note that you can use LinearLayoutManager even if your recyclerView is using constraintLayout.