Populate Fragment ListVIew from JSON object

Question

I dont know where is the error, logcat doesnt show anything

App is not starting, I just receive unfortunately app has stopped. It wont turn on.

Problem is in this fragment. I tried to populate listview with data received from free weather API, trough JOSN. Im using custom object HourlyForecast which contains data about temperature, precipitation, weather icon and time.

public class Tab3 extends Fragment {
Typeface weatherFont;

TextView timeField;
TextView precipitationField;
TextView temperatureField;
TextView weatherIcon;
ListView listView;
MyAdapter adapter;

ArrayList<HourlyForecast> hourlyForecastArrayList = new ArrayList<>();

Handler handler;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    weatherFont = Typeface.createFromAsset(getActivity().getAssets(), "fonts/weather.ttf");
    updateWeatherData("Belgrade");


}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.tab3, container, false);

    timeField = (TextView) v.findViewById(R.id.time_hourly_field);
    weatherIcon = (TextView) v.findViewById(R.id.weather_hourly_icon);
    precipitationField = (TextView) v.findViewById(R.id.precipitation_hourly_field);
    temperatureField = (TextView) v.findViewById(R.id.temperature_hourly_field);
    weatherIcon.setTypeface(weatherFont);
    listView = (ListView) v.findViewById(R.id.my_list);
    adapter = new MyAdapter(getActivity(), hourlyForecastArrayList);
    listView.setAdapter(adapter);


    return v;
}

private void updateWeatherData(final String city) {
    new Thread() {
        public void run() {
            final JSONObject json = RemoteFetch.getJSON(getActivity(), city, 2);
            if (json == null) {
                handler.post(new Runnable() {
                    public void run() {
                        Toast.makeText(getActivity(),
                                getActivity().getString(R.string.place_not_found),
                                Toast.LENGTH_LONG).show();
                    }
                });
            } else {
                handler.post(new Runnable() {
                    public void run() {
                        renderWeather(json);
                    }
                });
            }
        }
    }.start();
}

private void renderWeather(JSONObject json) {
    try {


        JSONArray listObjects = json.getJSONArray("list");
        for (int i = 0; i < listObjects.length(); i++) {
            DateFormat df = DateFormat.getDateTimeInstance();
            String time = df.format(new Date(json.getLong("dt") * 1000));

            String precipitation = listObjects.getJSONObject(i).getString("rain");

            String temperature = listObjects.getJSONObject(i).getJSONObject("main").getString("temp");

            int weatherIconId = listObjects.getJSONObject(i).getJSONArray("weather").getInt(0);

            HourlyForecast hourlyForecast = new HourlyForecast(time, precipitation, temperature, weatherIconId);
            hourlyForecastArrayList.add(hourlyForecast);

        }


    } catch (Exception e) {
        Log.e("SimpleWeather", "One or more fields not found in the JSON data");
        Toast.makeText(getActivity(), "No JSON data found", Toast.LENGTH_LONG).show();
    }
}

private void setWeatherIcon(int actualId, int day_night) {
    int id = actualId / 100;
    String icon = "";
    if (actualId == 800) {
        long currentTime = new Date().getTime();
        if (day_night == 1) {
            icon = getActivity().getString(R.string.weather_sunny);
        } else if (day_night == 2) {
            icon = getActivity().getString(R.string.weather_clear_night);
        }
    } else {
        switch (id) {
            case 2:
                icon = getActivity().getString(R.string.weather_thunder);
                break;
            case 3:
                icon = getActivity().getString(R.string.weather_drizzle);
                break;
            case 7:
                icon = getActivity().getString(R.string.weather_foggy);
                break;
            case 8:
                icon = getActivity().getString(R.string.weather_cloudy);
                break;
            case 6:
                icon = getActivity().getString(R.string.weather_snowy);
                break;
            case 5:
                icon = getActivity().getString(R.string.weather_rainy);
                break;
        }
    }
    weatherIcon.setText(icon);
}




class MyAdapter extends ArrayAdapter<HourlyForecast> {
    ArrayList<HourlyForecast> hourlyForecastArrayListInAdapter = new ArrayList<>();

    public MyAdapter(Context context, ArrayList<HourlyForecast> hourlyForecasts) {
        super(context, R.layout.row_hourly);
        hourlyForecastArrayListInAdapter = hourlyForecasts;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = getActivity().getLayoutInflater();
        View rowView = inflater.inflate(R.layout.row_hourly, null, true);

        HourlyForecast forecastInAdapter = hourlyForecastArrayListInAdapter.get(position);
        timeField.setText(forecastInAdapter.getTime());
        precipitationField.setText(forecastInAdapter.getPrecipitation());
        temperatureField.setText(forecastInAdapter.getTemperature());


        setWeatherIcon(forecastInAdapter.getWeatherIconId(), 1);


        return rowView;
    }
}

}

Here is a logcat

java.lang.NullPointerException
        at com.slobx.slobodan.weathermob.Tab3.onCreateView(Tab3.java:61)
        at android.support.v4.app.Fragment.performCreateView(Fragment.java:1789)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:955)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1138)
        at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:740)
        at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1501)
        at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:490)
        at android.support.v4.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:163)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:1105)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:951)
        at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1473)
        at android.view.View.measure(View.java:15172)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:833)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
        at android.view.View.measure(View.java:15172)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
        at android.support.v7.internal.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:124)
        at android.view.View.measure(View.java:15172)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1390)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:681)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
        at android.view.View.measure(View.java:15172)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
        at android.view.View.measure(View.java:15172)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1390)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:681)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
        at android.view.View.measure(View.java:15172)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2148)
        at android.view.View.measure(View.java:15172)
        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1848)
        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1100)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1273)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:998)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4212)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
        at android.view.Choreographer.doCallbacks(Choreographer.java:555)
        at android.view.Choreographer.doFrame(Choreographer.java:525)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
        at android.os.Handler.handleCallback(Handler.java:615)
        at android.os.Handler.dispatchMessage(Handler.java:92)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:4745)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
        at dalvik.system.NativeStart.main(Native Method)

Answer 1

This could be from a NullPointerException from being unable to instantiate the TextView .

Check your layout R.layout.tab3 to make sure that a TextView with an id of weather_hourly_icon actually exists.