LogCat error when running specific activity

Question

My application is not producing the information that it has been requested in the java files. It was hoped that the app would produce a recycler view of information that is being stored in a phpMyAdmin database.

However, all I am getting is a blank/empty activity.

The LogCat is producing an error that is to do with the RecyclerView, however, I am not sure how to get around this error/know if this is the error that is causing the blank activity.

LogCat

02-07 11:28:55.936 5622-5622/com.example.xxxx.myapplication E/RecyclerView: No adapter attached; skipping layout

Adapter

package com.example.benchalmers.myapplication;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.List;

public class ProductAdapter extends RecyclerView.Adapter<ProductAdapter.ProductViewHolder> {


    private Context mCtx;
    private List<Product> productList;

    public ProductAdapter(Context mCtx, List<Product> productList) {
        this.mCtx = mCtx;
        this.productList = productList;
    }

    @Override
    public ProductViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        LayoutInflater inflater = LayoutInflater.from(mCtx);
        View view = inflater.inflate(R.layout.list_layout, null);
        return new ProductViewHolder(view);

    }

    @Override
    public void onBindViewHolder(ProductViewHolder holder, int position) {

        Product product = productList.get(position);

        holder.textViewType.setText(product.getType());
        holder.textViewProperty.setText(product.getProperty());
        holder.textViewMoreInfo.setText(String.valueOf(product.getMoreInfo()));
        holder.textViewDate.setText(String.valueOf(product.getDate()));

        //holder.imageView.setImageDrawable(mCtx.getResources().getDrawable(product.getImage()));
    }

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

    class ProductViewHolder extends RecyclerView.ViewHolder {

        ImageView imageView;
        TextView textViewType, textViewProperty, textViewMoreInfo, textViewDate;

        public ProductViewHolder(View itemView) {
            super(itemView);

            imageView = itemView.findViewById(R.id.imageView);
            textViewType = itemView.findViewById(R.id.textViewType);
            textViewProperty = itemView.findViewById(R.id.textViewProperty);
            textViewMoreInfo = itemView.findViewById(R.id.textViewMoreInfo);
            textViewDate = itemView.findViewById(R.id.textViewDate);

        }
    }
}

Activity

package com.example.benchalmers.myapplication;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.widget.Toast;

import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;

public class Maintenance extends AppCompatActivity {

    private static final String PRODUCT_URL = "http://192.168.64.2/MyApi/api.php";

    RecyclerView recyclerView;
    private ProductAdapter adapter;

    List<Product> productList;

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

        productList = new ArrayList<>();

        recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        this.adapter = new ProductAdapter(this, productList);
        recyclerView.setAdapter(adapter);

        loadProducts ();

    }

    private void loadProducts () {

        StringRequest stringRequest = new StringRequest(Request.Method.GET, PRODUCT_URL,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {
                        try {
                            JSONArray products  =new JSONArray(response);

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

                                JSONObject productObject = products.getJSONObject(i);

                                int maintenance_id = productObject.getInt("maintenance_id");
                                String type = productObject.getString("type");
                                String property = productObject.getString("property");
                                String more_info = productObject.getString("more_info");
                                Double date = productObject.getDouble("date");

                                Product product = new Product(maintenance_id, type, property, more_info, date);
                                productList.add(product);

                            }

                            adapter = new ProductAdapter(Maintenance.this, productList);
                            recyclerView.setAdapter(adapter);

                        } catch (JSONException e) {
                            e.printStackTrace();
                        }

                    }
                },

                new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {

                Toast.makeText(Maintenance.this, error.getMessage(), Toast.LENGTH_SHORT).show();

                    }
                });

        Volley.newRequestQueue(this).add(stringRequest);

    }
}

I have not attached any Java files at this stage, as I do not believe that they are the issue here.

I have looked at various threads on Stack, but none of which seem to do the job.

Any guidance would be appreciated!

Like it says. You are not attaching an adapter with the `RecyclerView`. Can you add the activity here? — Napster, Feb 07 '18 at 16:38
Add the activity code where you add the adapter. This error is not from inside the adapter — Napster, Feb 07 '18 at 16:40
So you see how you are attaching the adapter inside the `StringRequest`? that is an `AsyncTask` which completes later. What you need to do is attach an empty adapter where you are setting the `RecyclerView` properties and then update the data inside the adapter later once the request completes — Napster, Feb 07 '18 at 16:43
Possible duplicate of [recyclerview No adapter attached; skipping layout](https://stackoverflow.com/questions/29141729/recyclerview-no-adapter-attached-skipping-layout) — Zoe, Feb 07 '18 at 16:44
Put Log.e("List_Size"," "+productList.size()); below of adapter = new ProductAdapter(Maintenance.this, productList); on your Activity and check the size of the list — Abhishek kumar, Feb 07 '18 at 16:45
This is off context but using JSONArray request would be better compared to StringRequest, as you are getting your response back in JSONArray format — kukroid, Feb 07 '18 at 16:49

Twometer · Answer 1 · 2018-02-07T16:59:02.160

0

As the error message says, you did not bind any Adapter to the RecyclerView so It cannot display anything and "skips the layout"

When you create an app with a RecyclerView, and you have written an Adapter, then you have to also attach that Adapter to the RecyclerView, which would something like this in your code:

private ProductAdapter adapter;

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

    productList = new ArrayList<>();

    recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    this.adapter = new ProductAdapter(this, productList);
    recyclerView.setAdapter(adapter)

    loadProducts ();

}

For more information about the RecyclerView, see this page from Android Developers.

Note, that in loadProducts();, after the request completes, you must not reinstantiate your Adapter but instead call this.adapter.notifyDataSetChanged();.

edited Feb 07 '18 at 16:59

answered Feb 07 '18 at 16:47

Twometer

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Could anyone who casts a downvote, please explain *why* you downvoted? Thanks. – Twometer Feb 07 '18 at 16:50
Without Api call without set data into pojo class , if you call Adapter it will send null list value to the Adapter class by constructor. – Abhishek kumar Feb 07 '18 at 16:52
@Abhishekkumar It does *not* send a null list to the adapter, because the list has beeen initialized with `new ArrayList<>();` before. When you update that, you have to call `notifyDataSetChanged()` to the Adapter, and then the UI will reflect the changes. At best, the ArrayList would have been declared within the Adapter, but that's probably just a design issue. – Twometer Feb 07 '18 at 16:54
According to your code first it will perform ProductAdapter adapter = new ProductAdapter(this, productList); recyclerView.setAdapter(adapter) then call loadProducts (); – Abhishek kumar Feb 07 '18 at 16:56
@Abhishekkumar That does not matter, because `loadProducts()` issues an asynchronous Request anyway. – Twometer Feb 07 '18 at 16:57
@Twometer You answer seems to have removed the error from the LogCat, however, no information (from the DB) appears on the application. No errors appearing in the LogCat. – Kali Ma Feb 07 '18 at 16:58
@KaliMa see my updated answer, I've forgot a note to make the UI update. – Twometer Feb 07 '18 at 16:59
check by log is your pojo class have data or not @KaliMa – Abhishek kumar Feb 07 '18 at 17:03
I'm not sure what you mean @Abhishekkumar. Can you clarify further? – Kali Ma Feb 07 '18 at 17:04
Activity updated with your suggestions @Twometer. However, still nothing showing on the emulator. – Kali Ma Feb 07 '18 at 17:06
@KaliMa In your `ProductAdapter` you have to also override `getItemCount` to return your list size, as it returns 0 when not specified. – Twometer Feb 07 '18 at 17:10
@Twometer Is this not what is happening here in my ProductAdapter: `@Override public int getItemCount() { return productList.size(); } class ProductViewHolder extends RecyclerView.ViewHolder { ImageView imageView; TextView textViewType, textViewProperty, textViewMoreInfo, textViewDate;` – Kali Ma Feb 07 '18 at 17:14
Oh, oops sorry I didn't see that, of course you're doing just that. What you can try now is adding a method `add` to your Adapter. Then use that add method in your request callback instead of the `add` method of the original list. The problem could also be that Java is pass-by-value and therefore the list in the adapter is not updated when you update the list in the Activity. – Twometer Feb 07 '18 at 17:17
Problem is only with your list – Abhishek kumar Feb 07 '18 at 17:24
@KaliMa see my comment for a possible solution, I forgot the @ mention – Twometer Feb 07 '18 at 17:38
Thanks for this @Twometer. I'm quite new at all this so not sure how to implement it. – Kali Ma Feb 07 '18 at 17:39
@KaliMa add `public void addProduct(Product p) {productList.add(p);}` to your **Adapter**, and then in `onResponse()`, instead of `productList.add(product);`, you write `adapter.addProduct(product);` – Twometer Feb 07 '18 at 21:06

LogCat error when running specific activity

1 Answers1