In my application, I want to run code every 120second and to achieve  this I am using Thread.
Following is the code snippet that I am using, but it is giving me Force close error.
Show me error for this line :
getActivity().runOnUiThread(new Runnable() {}
My Codes :
public class MainReminderFragment extends Fragment {
    @BindView(R.id.mainExplore_noExploreTxt)
    TextView mainExplore_noExploreTxt;
    @BindView(R.id.newsPageLoadLay)
    RelativeLayout newsPageLoadLay;
    @BindView(R.id.toolbarTitleTxt)
    TextView toolbarTitleTxt;
    private Context context;
    public List<Datum> model = new ArrayList<>();
    public ReminderAdapter reminderAdapter;
    private SharedPrefrencesHandler prefrencesHandler;
    private String token = "";
    private LinearLayoutManager layoutManager;
    private MainActivity mainActivity;
    private InterfaceApi api;
    private boolean isRunning = false;
    public ProgressBar mainExplore_progressBar;
    public RecyclerView mainExplore_recyclerView;
    public MainReminderFragment() {
        // Required empty public constructor
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_main_reminder, container, false);
        //Initialize
        ButterKnife.bind(this, view);
        context = getActivity();
        prefrencesHandler = new SharedPrefrencesHandler(context);
        reminderAdapter = new ReminderAdapter(context, model);
        layoutManager = new LinearLayoutManager(context);
        mainExplore_progressBar = view.findViewById(R.id.mainExplore_progressBar);
        mainExplore_recyclerView = view.findViewById(R.id.mainExplore_recyclerView);
        isRunning = true;
        mainActivity = (MainActivity) getActivity();
        api = ApiClient.getClient().create(InterfaceApi.class);
        //Toolbar name
        toolbarTitleTxt.setText(context.getResources().getString(R.string.reminder));
        //RecyclerView
        mainExplore_recyclerView.setLayoutManager(layoutManager);
        mainExplore_recyclerView.setHasFixedSize(true);
        //Get token
        token = prefrencesHandler.getFromShared(SharedPrefrencesKeys.TOKEN.name());
        //Get data
        getData();
        if (getActivity() != null) {
            Thread thread = new Thread() {
                @Override
                public void run() {
                    float i;
                    try {
                        for (i = 0; i <= 100; i++) {
                            getActivity().runOnUiThread(new Runnable() {
                                public void run() {
                                    getData();
                                }
                            });
                            sleep(120000);
                        }
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            };
            thread.start();
        }
        return view;
    }
    //Get data
    private void getData() {
        try {
            Call<SerialReminderListResponse> call = api.getListSerialReminder(token, "2", sendData(1));
            mainExplore_progressBar.setVisibility(View.VISIBLE);
            call.enqueue(new Callback<SerialReminderListResponse>() {
                @Override
                public void onResponse(Call<SerialReminderListResponse> call, Response<SerialReminderListResponse> response) {
                    if (response.body().getData() != null) {
                        if (response.body().getData().size() > 0) {
                            model.clear();
                            model.addAll(response.body().getData());
                            reminderAdapter.notifyDataSetChanged();
                            mainExplore_recyclerView.setAdapter(reminderAdapter);
                            //Gone no explore
                            mainExplore_noExploreTxt.setVisibility(View.GONE);
                        } else {
                            mainExplore_noExploreTxt.setVisibility(View.VISIBLE);
                            mainExplore_recyclerView.setVisibility(View.GONE);
                        }
                    }
                    mainExplore_progressBar.setVisibility(View.GONE);
                }
                @Override
                public void onFailure(Call<SerialReminderListResponse> call, Throwable t) {
                    mainExplore_progressBar.setVisibility(View.GONE);
                }
            });
        } catch (Exception e) {
        }
    }
Force close error in logCat :
Process: in.nouri.sevenwatchlist, PID: 7104
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.app.FragmentActivity.runOnUiThread(java.lang.Runnable)' on a null object reference
at com.app.test.Fragments.MainPageFrags.MainReminderFragment$1.run(MainReminderFragment.java:136)
 
     
     
     
    