Just implemented RecyclerView in my code, replacing ListView.
Everything works fine. The data is displayed.
But error messages are
It happens when you are not setting the adapter during the creation phase:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity);
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
....
}
public void onResume() {
super.onResume();
mRecyclerView.setAdapter(mAdapter);
....
}
Just move setting the adapter into onCreate with an empty data and when you have the data call:
mAdapter.notifyDataSetChanged();
I had this error, and I tried to fix for a while until I found the solution.
I made a private method buildRecyclerView, and I called it twice, first on onCreateView and then after my callback (in which I fetch data from an API). This is my method buildRecyclerView in my Fragment:
private void buildRecyclerView(View v) {
mRecyclerView = v.findViewById(R.id.recycler_view_loan);
mLayoutManager = new LinearLayoutManager(getActivity());
((LinearLayoutManager) mLayoutManager).setOrientation(LinearLayoutManager.VERTICAL);
mRecyclerView.setLayoutManager(mLayoutManager);
mAdapter = new LoanAdapter(mExampleList);
mRecyclerView.setLayoutManager(mLayoutManager);
mRecyclerView.setAdapter(mAdapter);
}
Besides, I have to modify the method get-Item-Count in my adapter, because On on-Create-View the list is null and it through an error. So, my get-Item-Count is the following:
@Override
public int getItemCount() {
try {
return mLoanList.size();
} catch (Exception ex){return 0;}
}
This issue is because you are not adding any LayoutManager for your RecyclerView.
Another reason is because you are calling this code in a NonUIThread. Make sure to call this call in the UIThread.
The solution is only you have to add a LayoutManager for the RecyclerView before you setAdapter in the UI Thread.
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
ArtistArrayAdapter adapter = new ArtistArrayAdapter(this, artists);
recyclerView = (RecyclerView) findViewById(R.id.cardList);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setAdapter(adapter);
Just replace above code with this and it should work. What you did wrong is you called setAdapter(adapter) before calling layout manager.
I was getting the same two error messages until I fixed two things in my code:
(1) By default, when you implement methods in the RecyclerView.Adapter it generates:
@Override
public int getItemCount() {
return 0;
}
Make sure you update your code so it says:
@Override
public int getItemCount() {
return artists.size();
}
Obviously if you have zero items in your items then you will get zero things displayed on the screen.
(2) I was not doing this as shown in the top answer: CardView layout_width="match_parent" does not match parent RecyclerView width
//correct
LayoutInflater.from(parent.getContext())
.inflate(R.layout.card_listitem, parent, false);
//incorrect (what I had)
LayoutInflater.from(parent.getContext())
.inflate(R.layout.card_listitem,null);
(3) EDIT: BONUS:
Also make sure you set up your RecyclerView like this:
<android.support.v7.widget.RecyclerView
android:id="@+id/RecyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
NOT like this:
<view
android:id="@+id/RecyclerView"
class="android.support.v7.widget.RecyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
I have seen some tutorials using the latter method. While it works I think it generates this error too.
Solved by setting the initialized empty list and adapter at the bottom and calling notifyDataSetChanged when results are fetched.
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getContext());
recyclerviewItems.setLayoutManager(linearLayoutManager);
someAdapter = new SomeAdapter(getContext(),feedList);
recyclerviewItems.setAdapter(someAdapter);