RecyclerView not calling onCreateViewHolder or onB

问题:

Not getting any errors and all the data seems valid. For some reason, nether of the view related methods are being called. I have made sure of the following:

• getItemCount() is the only adapter method being called and is returning a positive integer value, (I know this will be the area you guys will look at)

  • Constructor is being called, member variables are valid.

  • Parent View is a vertical LinearLayout; no scrollview, or any other view with their own scroll properties in sight.

  • containing fragment view is created and shown on screen.

Here is the declaration in the fragment followed by the adapter. Any help would be appreciated as this has be completely baffled.

SubMenuAdapter adapter = new SubMenuAdapter(getActivity(), mContentItems);
    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
    recyclerView.setItemAnimator(new DefaultItemAnimator());
    recyclerView.setAdapter(adapter);

public class SubMenuAdapter extends RecyclerView.Adapter<SubMenuAdapter.ViewHolder> {
private static final String TAG = String.format("==> %S", SubMenuAdapter.class.getSimpleName());

private final List<ContentItem> mContentItems;
private Context mContext;

public SubMenuAdapter(Context context, List<ContentItem> contenItems) {
    Log.d(TAG, "Constructor called");
    mContentItems = contenItems;
    mContext = context;
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    Log.d(TAG, "onCreateViewHolder called");
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_resource_efficiency, parent, false);
    return new ViewHolder(view);
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    Log.d(TAG, "onBindViewHolder called");

    ContentItem item = mContentItems.get(position);
    holder.textName.setText(item.getName());
    FontSetter.setMyriadProRegular(mContext, holder.textName);
    Picasso.with(mContext).load("file://" + item.getPreviewImageDefault()).into(holder.imageIcon);
}

@Override
public int getItemCount() {
    Log.d(mContext, String.format("getItemCount: %d", mContentItems.size()));
    return mContentItems.size();
}

// ViewHolder
public static class ViewHolder extends RecyclerView.ViewHolder {

    TextView textName;
    ImageView imageIcon;

    public ViewHolder(View view) {
        super(view);
        textName = (TextView) view.findViewById(R.id.tv_resource_efficiency_option);
        imageIcon = (ImageView) view.findViewById(R.id.iv_resource_efficiency_icon);
    }
}

回答1:

This may also help someone

First Use

recyclerView.setAdapter(adapter);

And then:

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

So it will look like this:

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

The order is reversed

回答2:

Been chasing answer for over an hour.

Dont forget to call this one liner before setting your adapter.

recyclerView.setLayoutManager(new LinearLayoutManager(this));

It seems that recycler view do not have default layout manager option built in so we have to programatically add it.

Cheers if you found it helpful.

回答3:

Make sure you recycle view is not child from nestedscrollview

for example, this code will not work.

<android.support.v4.widget.NestedScrollView
    android:id="@+id/responder_scroll"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/darkGray"
    android:clipToPadding="false"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <android.support.v7.widget.CardView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="24dp"
            app:cardElevation="@dimen/spacing_medium"
            app:cardUseCompatPadding="true">

            <RelativeLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content">

                <TextView
                    android:id="@+id/responder_testimonial"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_alignParentTop="true"
                    android:text="Testimonial"
                    android:textSize="@dimen/general_font_size" />

                <TextView
                    android:id="@+id/responder_counter_testimonial"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_toRightOf="@+id/responder_testimonial"
                    android:text="170"
                    android:textSize="@dimen/general_font_size_small" />

                <Button
                    android:id="@+id/responder_btn_testimonial"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_alignParentRight="true"
                    android:layout_alignParentTop="true"
                    android:text="Go" />

               <view
                    android:id="@+id/responder_list_testimonial"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:layout_below="@+id/responder_testimonial"
                    class="android.support.v7.widget.RecyclerView"/>
            </RelativeLayout>
        </android.support.v7.widget.CardView>

    </FrameLayout>
</android.support.v4.widget.NestedScrollView>

then i use,

<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">

<view
    android:id="@+id/responder_list_testimonial"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_below="@+id/responder_testimonial"
    class="android.support.v7.widget.RecyclerView"/>

回答4:

I don't know if this will be helpful to anyone, but I almost had the same exact problem. My problem was not in either the fragment/class nor the recycler adapter. The problem was in parent XML layout where the actionbar took match_parent where the FrameLayout -in which the fragment is replaced- didn't get any available place to be shown. That's why the methods weren't called.

I guess similar scenarios might be the case for those facing the same problem. Double check every width and height in every XML file might be in the same tree, as the problem doesn't seem to be in the adapter at all.

回答5:

My two pennies here. Just spent more than three hours debugging this.

Make sure that you have not used the following line carelessly.

recyclerView.setHasFixedSize(true);

Set the fixed size only when you are sure that the view would have a constant size. In case it is not, the onCreateViewHolder and onBindView methods might not get called at all.

回答6:

I had also face the same issue where onCreateViewHolder or onBindView method was not getting invoke, only getItemCount was getting invoked. So it was basically issue with the height and weight of RecyclerView which was set to wrap_content or 0dp. After changing it to some value fixed the problem.

回答7:

This is really old already, but in my case, I was using a ConstraintLayout and the height was set wrong so my view would have 0dp and then the adapter would be saving to do its job, as the view is 0dp.

Make sure height and width is ok and RecyclerView is has a positive size.

回答8:

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.

回答9:

I know this topic is old, but if you did the same learner mistake, as I did, you might find this helpful.

As I was studying on some website about RecyclerView and copying some code and adapting to my context, I have created different variables (eg users and data) which were meant to do the same thing, except some methods were calling data and some were calling users. This is an easy mistake to do as you try to understand other's code and java functionality (it happens to me all the time).

It's good to know that you can println in your console anywhere in your java code, so you can debug like that pretty easily.

Good luck!

回答10:

In my case it was using setHasStableIds(true); in the adapter while some list items were returning -1 in getItemID(), so I suppose the RecyclerView was thinking they are equal.

回答11:

I had this same issue where neither onCreateViewHolder or onBindViewHolder were being called. Changing your onCreateViewHolder method to use the Context you saved a reference to in the constructor instead of doing parent.getContext() should fix it:

public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    Log.d(TAG, "onCreateViewHolder called");
    View view = LayoutInflater.from(mContext).inflate(R.layout.row_resource_efficiency, parent, false);
    return new ViewHolder(view);

回答12:

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.

Link to the answer

回答13:

I recently encountered this problem and apparently there are many possible causes. Try one or combination of these options, see which one(s) work(s) for you :)

1. Layout manager
Ensure that you set a layout manager to your recycler view as below

// create a layout manager
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(my_context);
linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);

// get recycler view
RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_id);
// set
recyclerView.setLayoutManager(linearLayoutManager);

2. Fixed Size
Ensure that you state whether your recycler view has a fixed size or not

// set fixed size
recyclerView.setHasFixedSize(true); // or false depending on implementation

3. XML
Ensure that your recycler is not nested in too many layouts which may cause confusion such as combination of ScrollView and RelativeLayout. Make it simple, see if it fixes your issue

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<android.support.v7.widget.RecyclerView
android:id="@+id/thread_list"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>

回答14:

In my case a had a Fragment with RecyclerView inside a ViewPager. The issue appeared because i used Fragment.getFragmentManager() instead of Fragment.getChildFragmentManager for my FragmentStatePagerAdapter's constructor.

P.S. Using Layout Inspector might be a great help at debugging this sort of issue.

回答15:

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