i got error message : recyclerview No adapter attached; skipping layout when i try to fetch data and store to recyclerview

here is my code:

public class MainActivity extends AppCompatActivity {

private DataAdapter dataAdapter;
private ArrayList<OrderListArray> orderListArrays=new ArrayList<>();
private RecyclerView mRecyclerView;
private ProgressBar mProgressBar;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    getData();

    mProgressBar=(ProgressBar)findViewById(R.id.progress_bar);
    mProgressBar.setVisibility(View.VISIBLE);
    mRecyclerView=(RecyclerView)findViewById(R.id.order_list);
    mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
}

public void getData(){
    String userToken = Preferences.getUserToken(getBaseContext());
    Log.d("[DEBUG]", "userToken: "   userToken);
    Call<List<OrderListArray>> getDataCall = ApiClient.getUserService().getJson("Bearer "   userToken);

    getDataCall.enqueue(new Callback<List<OrderListArray>>() {
        @Override
        public void onResponse(Call<List<OrderListArray>> call, Response<List<OrderListArray>> response) {

            mProgressBar.setVisibility(View.GONE);
            if (response.isSuccessful() && response.body()!=null) {
                orderListArrays = new ArrayList<>(response.body());
                  dataAdapter=new DataAdapter(orderListArrays,MainActivity.this);
                  mRecyclerView.setAdapter(dataAdapter);
            }
        }

        @Override
        public void onFailure(Call<List<OrderListArray>> call, Throwable t) {
              mProgressBar.setVisibility(View.GONE);
            Toast.makeText(MainActivity.this,"Failure",Toast.LENGTH_SHORT).show();
        }
    });
}

}

CodePudding user response：

use this code :

    public class MainActivity extends AppCompatActivity {
    
    private DataAdapter dataAdapter;
    private ArrayList<OrderListArray> orderListArrays=new ArrayList<>();
    private RecyclerView mRecyclerView;
    private ProgressBar mProgressBar;
    
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    
        getData();
    
        mProgressBar=(ProgressBar)findViewById(R.id.progress_bar);
        mProgressBar.setVisibility(View.VISIBLE);
        mRecyclerView=(RecyclerView)findViewById(R.id.order_list);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        //change here
        dataAdapter=new DataAdapter(orderListArrays,this);
        mRecyclerView.setAdapter(dataAdapter);
    }
    
    public void getData(){
        String userToken = Preferences.getUserToken(getBaseContext());
        Log.d("[DEBUG]", "userToken: "   userToken);
        Call<List<OrderListArray>> getDataCall = ApiClient.getUserService().getJson("Bearer "   userToken);
    
        getDataCall.enqueue(new Callback<List<OrderListArray>>() {
            @Override
            public void onResponse(Call<List<OrderListArray>> call, Response<List<OrderListArray>> response) {
    
                mProgressBar.setVisibility(View.GONE);
                if (response.isSuccessful() && response.body()!=null) {
                    orderListArrays = new ArrayList<>(response.body());
                    //change here
                    dataAdapter.notifyDataSetChanged()
                }
            }
    
            @Override
            public void onFailure(Call<List<OrderListArray>> call, Throwable t) {
                  mProgressBar.setVisibility(View.GONE);
                Toast.makeText(MainActivity.this,"Failure",Toast.LENGTH_SHORT).show();
            }
        });
    }
}

CodePudding user response：

I guess it is because you have some operation that must run in the Main Thread, but you write your code in the background thread(onResponse method), to solve this, you can create an interface callback, and invoke your callback method in onResponse and update your UI in the main thread.

public interface MyCallBack {
    void onGetResponse(Object response);
}

make your MainActivity to implement from MyCallBack

public class MainActivity extends AppCompatActivity implements MyCallBack 

create a field like this in your activity

public class MainActivity extends AppCompatActivity implements MyCallBack {
    private MyCallback myCallback;

and in your onCreate of your main activity initialize it

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    myCallback = this;
    setContentView(R.layout.activity_main);

in your onResponse do this:

public void onResponse(Call<List<OrderListArray>> call, Response<List<OrderListArray>> response) {
    if (response.isSuccessful() && response.body()!=null) {
            myCallback.onGetResponse(response.body());
    }
}

on onGetResponse method update your ui:

@Override
public void onGetResponse(Object response) {
    mProgressBar.setVisibility(View.GONE);
    orderListArrays = new ArrayList<>(response.body());
    dataAdapter=new DataAdapter(orderListArrays,MainActivity.this);
    mRecyclerView.setAdapter(dataAdapter);
}