Context is null in set adapter

Question

I have searched a lot this question and nothing work for me. i am trying to set forecast data into recyclerview and want set that data in a list via adapter here is a piece of code for my adapter...

public Adapter(Context context, List<ForecastCondition> data) {

    this.context = context;
    inflater = LayoutInflater.from(context);
    this.data = data;

}

i have set my adapter in a fragment and in asynctask method of postExecute to set the list in adapter i am using this code...

mAdapter = new Adapter(getContext(), datalist);
                    mRVFishPrice.setAdapter(mAdapter);
                    final LinearLayoutManager layoutManager = new LinearLayoutManager(getContext());
                    layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
                    mRVFishPrice.setLayoutManager(layoutManager);

my logcat is

E/AndroidRuntime: FATAL EXCEPTION: main
                                                                         Process: com.example.om.weahterapp, PID: 19218                                                                             java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.content.Context.getSystemService(java.lang.String)' on a null object reference
                                                                               at android.view.LayoutInflater.from(LayoutInflater.java:219)
                                                                               at data.Adapter.<init>(Adapter.java:38)
                                                                               at Fragments.ForecastFragment$ForecastTask.onPostExecute(ForecastFragment.java:153)
                                                                               at Fragments.ForecastFragment$ForecastTask.onPostExecute(ForecastFragment.java:101)
                                                                               at android.os.AsyncTask.finish(AsyncTask.java:632)
                                                                               at android.os.AsyncTask.access$600(AsyncTask.java:177)
                                                                               at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
                                                                               at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                               at android.os.Looper.loop(Looper.java:135)
                                                                               at android.app.ActivityThread.main(ActivityThread.java:5253)
                                                                               at java.lang.reflect.Method.invoke(Native Method)
                                                                               at java.lang.reflect.Method.invoke(Method.java:372)
                                                                               at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
                                                                               at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

EDIT

I have tried getActivity() and as well as FragmentActivity() but it doesn't work for me.

FRAGMENT

public class ForecastFragment extends Fragment {
private RecyclerView mRVFishPrice;
private Adapter mAdapter;
Context mContext;
List<ForecastCondition> datalist = new ArrayList<>();
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";

// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;

View view;

private OnFragmentInteractionListener mListener;

public ForecastFragment() {
    // Required empty public constructor
}

/**
 * Use this factory method to create a new instance of
 * this fragment using the provided parameters.
 *
 * @param param1 Parameter 1.
 * @param param2 Parameter 2.
 * @return A new instance of fragment ForecastFragment.
 */
// TODO: Rename and change types and number of parameters
public static ForecastFragment newInstance(String param1, String param2) {
    ForecastFragment fragment = new ForecastFragment();
    Bundle args = new Bundle();
    args.putString(ARG_PARAM1, param1);
    args.putString(ARG_PARAM2, param2);
    fragment.setArguments(args);
    return fragment;
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (getArguments() != null) {
        mParam1 = getArguments().getString(ARG_PARAM1);
        mParam2 = getArguments().getString(ARG_PARAM2);
    }
    mContext = getActivity();
    CityPreference cityPreference = new CityPreference(getActivity());

    renderForecastData(cityPreference.getCity());
}

public void renderForecastData(String city) {
    ForecastTask forecastTask = new ForecastTask();
    forecastTask.execute(new String[]{city});

}

private class ForecastTask extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... params) {
        try {

            String data = ((new ForecastHttpClient()).getForecast(params[0]));
            Log.v("doInBackground:" ,data);
            return data;
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;

    }

    @Override
    protected void onPostExecute(String data) {
        super.onPostExecute(data);
        try {
            Log.v("postExecute:",data);
            JSONObject jObj = new JSONObject(data);
            JSONArray jArr = jObj.getJSONArray("list");

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

                JSONObject jDayForecast = jArr.getJSONObject(i);
                ForecastCondition forecastCondition = new ForecastCondition();
                forecastCondition.lastupdateForecast = jDayForecast.getLong("dt");

                JSONObject tempObj = jDayForecast.getJSONObject("temp");
                forecastCondition.dayTempForecast = (float) tempObj.getDouble("day");
                forecastCondition.minTempForecast = (float) tempObj.getDouble("min");
                forecastCondition.maxTempForecast = (float) tempObj.getDouble("max");
                forecastCondition.nightTempForecast = (float) tempObj.getDouble("night");
                forecastCondition.eveTempForecast = (float) tempObj.getDouble("eve");
                forecastCondition.morningTempForecast = (float) tempObj.getDouble("morn");

                forecastCondition.pressureForecast = (float) jDayForecast.getDouble("pressure");
                forecastCondition.humidityForecast = (float) jDayForecast.getDouble("humidity");

                JSONArray weatherArray = jDayForecast.getJSONArray("weather");
                JSONObject jsonWeather = weatherArray.getJSONObject(0);
                forecastCondition.weatherIdForecast = jsonWeather.getInt("id");
                forecastCondition.conditionForecast = jsonWeather.getString("main");
                forecastCondition.descriptionForecast = jsonWeather.getString("description");
                forecastCondition.iconForecast = jsonWeather.getString("icon");

                datalist.add(forecastCondition);
            }


                mAdapter = new Adapter(mContext, datalist);
                mRVFishPrice.setAdapter(mAdapter);
                final LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
                layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
                mRVFishPrice.setLayoutManager(layoutManager);
                // mRVFishPrice.setLayoutManager(new LinearLayoutManager(getContext()));

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

    }

}

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

    view = inflater.inflate(R.layout.fragment_forecast, container, false);
    mRVFishPrice = (RecyclerView) view.findViewById(R.id.fishPriceList);

    // Inflate the layout for this fragment
    return view;
}

// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
    if (mListener != null) {
        mListener.onFragmentInteraction(uri);
    }
}

@Override
public void onAttach(Context context) {
    super.onAttach(context);
    if (context instanceof OnFragmentInteractionListener) {
        mListener = (OnFragmentInteractionListener) context;
    } else {
        throw new RuntimeException(context.toString()
                + " must implement OnFragmentInteractionListener");
    }
}

@Override
public void onDetach() {
    super.onDetach();
    mListener = null;
}


public interface OnFragmentInteractionListener {
    // TODO: Update argument type and name
    void onFragmentInteraction(Uri uri);
}

}

My app is crash whenever i call this line from MainActivity

new ForecastFragment().renderForecastData(newCity);

Instead of getContext() add getActivity() and set your LinearLayoutManager above your adapter code. — Akash, Jan 30 '17 at 11:42
i have tried lots of things like getActivity() , FragmentActivity() etc. but nothing work for me — Hiren Gujarati, Jan 30 '17 at 11:43
does this happen all the time ? see my answer i think it's the same case — yanivtwin, Jan 30 '17 at 12:06
@yanivtwin no, it doesn't happen in every time. on firsttime open application it working fine but i have put change city option and on clicking there i am re execute this asynctask method. and on invoke this method the app is crashing — Hiren Gujarati, Jan 30 '17 at 12:09
ok than , it seems like the right answer , it's caused because of the asynctask , your getactivity returns null... — yanivtwin, Jan 30 '17 at 12:13

yanivtwin · Accepted Answer · 2017-01-30T12:52:57.360

1

If you're calling the constructor somewhere else and not in the oncreate or onviewcreated and such you need to save the context like so in the fragment onviewcreated or oncreateview:

Context mContext = getActivity();

and than use mContext , this is true if you are using fragments ofcourse.

that is caused if ondetached is called before your constructor is called , it seems like this is your answer from your edit but post the full fragment to be sure.

UPDATE:

after further investigation it seems that oncreate in the fragment won't do in this case , see this image https://www.tutorialspoint.com/android/images/fragment.jpg oncreate still has a null getactivity , getactivity needs to be in onattach onviewcreated or oncreateview

you need to add this code to your fragment:

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        mContext = getActivity();
    }

once you do this , don't use getactivity or getcontext anymore , use mContext only

edited Jan 30 '17 at 12:52

answered Jan 30 '17 at 11:52

yanivtwin

617
8
32

i have tried this in oncreate method but it doesn't work for me. – Hiren Gujarati Jan 30 '17 at 12:15
can you post your fragment ? it will be much easier to help this way – yanivtwin Jan 30 '17 at 12:17
i have edited question and added full fragment code have a look and please help me to sort out. – Hiren Gujarati Jan 30 '17 at 12:22
ok try this updated answer – yanivtwin Jan 30 '17 at 12:32
no it doesn't work for me nullpointer exception for context is pointed at adapter – Hiren Gujarati Jan 30 '17 at 12:40
you're still using getActivity() in this line ? final LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity()); if so change it to mContext aswell – yanivtwin Jan 30 '17 at 12:45
i have already changed that line but thats not work for me. – Hiren Gujarati Jan 30 '17 at 12:59
thanks for your help. but i am still stuck at that point. i have researched a lot and i got to knew that i have to point context somewhere but where? i have edited my question.. plz help me. – Hiren Gujarati Jan 31 '17 at 13:00
post a new question i'm having a hard time understanding the problem now – yanivtwin Feb 01 '17 at 18:10

score 0 · Answer 2 · answered Jan 30 '17 at 11:46

0

use getApplicationContext() or YourActivityName.this instead of getContext()

answered Jan 30 '17 at 11:46

Matiullah Karimi

1,234
1
15
17

score 0 · Answer 3 · answered Jan 30 '17 at 11:46

0

For Activity -> Use Activity.this For Fragment -> use getActivity() instead of using getContext(

answered Jan 30 '17 at 11:46

Sanjiv Patel

11
2

Krupa Kakkad · Answer 4 · 2017-01-30T12:27:51.833

0

Try like this:

private Activity context;


public Adapter(Activity context, List<ForecastCondition> data) {

   this.context = context;
   inflater = LayoutInflater.from(context);
   this.data = data;
}

And set adapter like this:

mAdapter = new Adapter(getActivity(), datalist);
mRVFishPrice.setAdapter(mAdapter);

edited Jan 30 '17 at 12:27

answered Jan 30 '17 at 11:49

Krupa Kakkad

857
1
13
28

plz read question carefully . i am using fragment so activity.this doesn't work. – Hiren Gujarati Jan 30 '17 at 11:57
okay, see updated answer. – Krupa Kakkad Jan 30 '17 at 12:29
no it doesn't work for me same error. – Hiren Gujarati Jan 30 '17 at 12:34
Have you changed public Adapter(Activity context, List data) this line? – Krupa Kakkad Jan 30 '17 at 12:37
yaah i have changed COntext to activity but that's not working – Hiren Gujarati Jan 30 '17 at 12:58

score 0 · Answer 5 · answered Jan 30 '17 at 12:03

0

Try this instead of getContext() to getActivity()

 mAdapter = new Adapter(getActivity(), datalist);
                mRVFishPrice.setAdapter(mAdapter);
                final LinearLayoutManager layoutManager = new LinearLayoutManager(getContext());
                layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
                mRVFishPrice.setLayoutManager(layoutManager);

answered Jan 30 '17 at 12:03

sunil

796
1
8
28

please read question carefully. i have already tried this and it doesn't work therefore i have to post question – Hiren Gujarati Jan 30 '17 at 12:06
in your Main Drawer Activity class set `public static Activity activityContext;` and set `activityContext=this;` from `onCreate()` method then while set adapter instead of getContext() used `your class name.activityContext` – sunil Jan 30 '17 at 12:15

score 0 · Answer 6 · answered Jan 30 '17 at 12:10

0

First set the layout manager and then set the adapter

mRVFishPrice.setLayoutManager(new LinearLayoutManager(getActivity(), LinearLayoutManager.VERTICAL, false));
mAdapter = new Adapter(getActivity(), datalist);
mRVFishPrice.setAdapter(mAdapter);

answered Jan 30 '17 at 12:10

AbhayBohra

2,047
24
36

Context is null in set adapter

6 Answers6