How to use setContentView in fragment instead of an activity

Question

Dear Stackoverflowers:)

AllAssetsFragment is opened from the MainActivity. In this fragment, I have trouble setting up the setContentView() and getApplicationContext() properly.

I know there is something wrong. Some of the code works for normal activities but they are not working in this fragment.

AllAssetsFragment:

import android.content.Intent;
import android.os.Bundle;

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import androidx.room.Room;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonArrayRequest;
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 AllAssetsFragment extends Fragment {

    public AllAssetsFragment(){


    }


    private static final String HI = "https://uniqueandrocode.000webhostapp.com/hiren/favouritelist.php";
    private List<AssetsItem>assetsItems;
    private RecyclerView recyclerView;
    AssetsAdapter adapter;

    private JsonArrayRequest request;
    private RequestQueue requestQueue;
    public static FavoritesDatabase favoritesDatabase;
    Button btn;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        return inflater.inflate(R.layout.fragment_allassets, container, false);


        recyclerView = (RecyclerView)getView().findViewById(R.id.recyclerview);
        recyclerView.setHasFixedSize(true);
        // +++ PROBLEM 1: Context doesn't work (same on Problem 3 and 4) +++
        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        assetsItems = new ArrayList<>();
        btn=(Button)getView().findViewById(R.id.favbtn);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                // +++ PROBLEM 2: This code doesn't work to open Fragment from Fragment +++
                startActivity(new Intent(AllAssetsFragment.this, FavoritesFragment.class));
            }


        });
        favoritesDatabase = Room.databaseBuilder(getActivity().getApplicationContext(), FavoritesDatabase.class, "myfavdb").allowMainThreadQueries().build();
        getData();

    }

    private void getData() {
        request = new JsonArrayRequest(HI, new Response.Listener<JSONArray>() {
            @Override
            public void onResponse(JSONArray response) {
                JSONObject jsonObject = null;
                for (int i = 0; i < response.length(); i++) {
                    try {
                        JSONObject ob = response.getJSONObject(i);
                        AssetsItem pr = new AssetsItem(ob.getInt("id"),
                                ob.getString("product_name"),
                                ob.getString("product_img"));
                        assetsItems.add(pr);

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
                setupData(assetsItems);
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {

            }
        });

        // +++ PROBLEM 3: Context doesn't work +++
        requestQueue = Volley.newRequestQueue(this);
        requestQueue.add(request);
    }

    private void setupData(List<AssetsItem>assetsItems){
    adapter=new AssetsAdapter(assetsItems,getActivity().getApplicationContext());
    recyclerView.setAdapter(adapter);
    }
}

And here our 2nd Fragment: FavoritesFragment:

import android.os.Bundle;

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import java.util.List;


/**
 * A simple {@link Fragment} subclass.
 */
public class FavoritesFragment extends Fragment {


    public FavoritesFragment() {

    }

    private RecyclerView rv;
    private FavoritesAdapter adapter;

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        return inflater.inflate(R.layout.fragment_favorites, container, false);

        rv=(RecyclerView)getView().findViewById(R.id.rec);
        rv.setHasFixedSize(true);
        // +++ PROBLEM 4: doesn't work +++
        rv.setLayoutManager(new LinearLayoutManager(this));

        getFavData();
    }

    private void getFavData(){
        List<FavoritesItem>favoritesItems=AllAssetsFragment.favoritesDatabase.favoritesDao().getFavoritesData();

        adapter = new FavoritesAdapter(favoritesItems,getActivity().getApplicationContext());
        rv.setAdapter(adapter);
    }



}

Answer 1

Don't use setContentView() within fragments. You should init your view in onCreateView() , like you already do.

About application context, I see that you are passing it to your adapter. I would argue that you don't need the application context there, as the context of the fragment should be enough. You can pass requireContext() .

You will also need to setup your RecyclerView and adapter from onCreateView() .

Answer 2

These are the mistakes you made in your code.

AllAssetsFragment

• Move the line below to the bottom of the onCreateView() method. It is a return statement, therefore, it has to be the last thing in the function.

   return inflater.inflate(R.layout.fragment_allassets, container, false);

• You can't use startActivity(...) to launch a fragment. This method is strictly for launching activities. To learn how to launch a fragment, check this awesome answer out.

• Replace this with getActivity() in the lines below:

  recyclerView.setLayoutManager(new LinearLayoutManager(this));
requestQueue = Volley.newRequestQueue(this);

FavoritesFragment

• Replace this with getActivity() in the line below:

  rv.setLayoutManager(new LinearLayoutManager(this));

Addendum:

To launch a fragment within an activity (in your case, MainActivity), follow the following steps:

1. In your activity_main.xml file, create a FrameLayout that would house your fragment, you can give it an id: container . If you don't know how to do this, just paste the code below:

    <FrameLayout android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/container" />

2. When you want to launch a fragment from an activity, simply use this code snippet:

    FragmentTransaction transaction = getFragmentManager().beginTransaction(); transaction.replace(R.id.container, new AllAssetsFragment()); transaction.commit();

3. When you want to launch a fragment from another fragment, simply use this code snippet:

    FragmentTransaction transaction = getActivity().getFragmentManager().beginTransaction(); transaction.replace(R.id.container, new AllAssetsFragment()); transaction.commit();

4. In the code snippets above, if getFragmentManager() does not work or if you are using AndroidX, use getSupportFragmentManager() instead.

Answer 3

You don't call setContentView in fragments you need return view in onCreateView method. you have already done.

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.fragment_allassets, container, false);
}

and for getApplicationContext you need to call getActivity()

like this

getActivity().getApplicationContext()