Maps don't load after i open the activity second time

Question

I have a map activity that displays the location of where the user is.When i open the activity for the first time everything is good.But if i go somewhere else and open the activity again it doesn't display where the user is just the map of Europe(so i guess it doesn't recognize the gps). Here is the code of this

public class Map extends AppCompatActivity implements LocationListener, OnMapReadyCallback, NavigationView.OnNavigationItemSelectedListener {


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

    getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
    toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    getSupportActionBar().setDisplayShowTitleEnabled(false);
    toolbar.setTitle("");
    toolbar.setSubtitle("");

    //gpsStatus = (TextView) findViewById(R.id.gpsStatus);
    dis = (TextView) findViewById(R.id.distancePreview);

    newActL = (RelativeLayout) findViewById(R.id.newAct);
    startActL = (RelativeLayout) findViewById(R.id.Act);
    timer = (TextView) findViewById(R.id.timePreview);

    newActB = (ImageButton) findViewById(R.id.newActB);
    stopActB = (ImageButton) findViewById(R.id.stopActB);
    gearMap = (ImageButton) findViewById(R.id.gearmap);

    List<String> spinnerArray = new ArrayList<String>();
    spinnerArray.add("Arrival");
    spinnerArray.add("Departure");

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(
            this, android.R.layout.simple_spinner_item, spinnerArray);

    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    sItems = (Spinner) findViewById(R.id.ardep);
    sItems.setAdapter(adapter);

    List<String> spinnerArray2 = new ArrayList<String>();
    spinnerArray2.add("Running");
    spinnerArray2.add("Walking");
    spinnerArray2.add("Cycling");
    spinnerArray2.add("Roller skating");
    spinnerArray2.add("Skateboarding");
    spinnerArray2.add("Kickbiking");
    spinnerArray2.add("Teleporting");

    ArrayAdapter<String> adapter2 = new ArrayAdapter<String>(
            this, android.R.layout.simple_spinner_item, spinnerArray2);

    adapter2.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    actCombo = (Spinner) findViewById(R.id.actCombo);
    actCombo.setAdapter(adapter2);
    Calendar rightNow = Calendar.getInstance();
    int currentHour = rightNow.get(Calendar.HOUR_OF_DAY);
    if (currentHour < 12) {
        actCombo.setSelection(GetInfo.arract - 1);
        sItems.setSelection(0);
    } else {
        actCombo.setSelection(GetInfo.depact - 1);
        sItems.setSelection(1);
    }

    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
            ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        return;
    }
    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,
            3000,
            1, this);

    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.mapview);
    mapFragment.getMapAsync(this);
    line = new PolylineOptions().width(3).color(Color.BLUE);

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.addDrawerListener(toggle);
    toggle.syncState();

    navigationView = (NavigationView) findViewById(R.id.nav_view);
    headerView = navigationView.getHeaderView(0);
    fullnameside = (TextView) headerView.findViewById(R.id.fullnameside);
    emailside = (TextView) headerView.findViewById(R.id.emailside);
    fullnameside.setText("" + GetInfo.fullname);
    emailside.setText("" + GetInfo.email);

    navigationView.setNavigationItemSelectedListener(this);
    navigationView.getMenu().getItem(1).setChecked(true);

}

private void getLocation() {
    //Toast.makeText(getBaseContext(), "e paides", Toast.LENGTH_SHORT).show();
    String locationProvider = LocationManager.NETWORK_PROVIDER;
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        // TODO: Consider calling
        //    ActivityCompat#requestPermissions
        // here to request the missing permissions, and then overriding
        //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
        //                                          int[] grantResults)
        // to handle the case where the user grants the permission. See the documentation
        // for ActivityCompat#requestPermissions for more details.
        return;
    }
    Location location = locationManager.getLastKnownLocation(locationProvider);
    try {
        line.add(new LatLng(location.getLatitude(), location.getLongitude()));
        GMap.addMarker(new MarkerOptions().position(new LatLng(location.getLatitude(), location.getLongitude())).title(""));
        GMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(location.getLatitude(), location.getLongitude()), 16.0f));
        steps++;
        getloc = true;
    } catch (NullPointerException e) {
        //Toast.makeText(this.getBaseContext(), "gyhg" + e.toString(), Toast.LENGTH_LONG).show();
    }
}

public void StopTrip(View v) {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage("Stop and upload your trip?")
            .setCancelable(true)
            .setNegativeButton("NO", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {

                }
            })
            .setPositiveButton("YES", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    float finalDistance = (float) (distance / 1000.0);
                    if (finalDistance < 2) {
                        Intent myIntent = new Intent(Map.this, Profile.class);
                        startActivity(myIntent);
                    }
                    TimeBuff += MillisecondTime;
                    handler.removeCallbacks(runnable);
                    // newActL.setVisibility(View.GONE);
                    // startActL.setVisibility(View.VISIBLE);
                    enabledActivity = false;
                    //database post
                    try {
                        Date currentTime = Calendar.getInstance().getTime();
                        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
                        String formattedDate = df.format(currentTime);

                        Date currentTime2 = Calendar.getInstance().getTime();
                        SimpleDateFormat df2 = new SimpleDateFormat("yyyy-MM-dd%20HH:mm:ss");
                        dateActEnd = df2.format(currentTime2);

                        String act = actCombo.getSelectedItem().toString();
                        String act_id = "7";
                        switch (act) {
                            case "Running":
                                act_id = "1";
                                break;
                            case "Walking":
                                act_id = "2";
                                break;
                            case "Cycling":
                                act_id = "3";
                                break;
                            case "Roller skating":
                                act_id = "4";
                                break;
                            case "Skateboarding":
                                act_id = "5";
                                break;
                            case "Kickbiking":
                                act_id = "6";
                                break;
                            case "Teleporting":
                                act_id = "7";
                                break;
                        }

                        String direcor;
                        if (sItems.getSelectedItem().toString().equals("Arrival"))
                            direcor = "arrival";
                        else
                            direcor = "departure";

                        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
                        StrictMode.setThreadPolicy(policy);
                        // String.format("%.1f", finalDistance)
                        URL obj = new URL("https://gekon.technologypark.cz/api/v1/record/create?user=" + LoginInfo.UserID
                                + "&date=" + formattedDate + "&distance=" + String.format("%.1f", finalDistance) + "&direction=" + direcor
                                + "&activity=" + act_id + "&polyline=" + PolyUtil.encode(line.getPoints()) + "&start=" + dateActStart
                                + "&end=" + dateActEnd + "&source=mobileapp");

                        HttpsURLConnection conn = (HttpsURLConnection) obj.openConnection();
                        conn.setRequestMethod("POST");
                        conn.setRequestProperty("ApiSecret", LoginInfo.ApiSecret);
                        conn.connect();
                        BufferedReader br = new BufferedReader(new InputStreamReader((conn.getInputStream())));
                        StringBuilder sb = new StringBuilder();
                        String output;
                        while ((output = br.readLine()) != null)
                            sb.append(output);

                        JSONObject jsonObj = new JSONObject(sb.toString());
                        JSONObject curRecord = new JSONObject(jsonObj.getString("data"));

                        Trips.datet.add(currentTime);
                        Trips.datestr.add(formattedDate);
                        Trips.act.add(act_id);
                        Trips.tripType.add(sItems.getSelectedItem().toString());
                        Trips.dist.add(String.format("%.1f", finalDistance));
                        Trips.trip_ids.add(curRecord.getString("trip_id"));
                        Trips.calc(++Trips.points);

                        TripsCalendarInfo.datet.add(currentTime);
                        TripsCalendarInfo.act.add(act_id);
                        TripsCalendarInfo.act_str.add(act);
                        TripsCalendarInfo.tripType.add(sItems.getSelectedItem().toString());
                        TripsCalendarInfo.dist.add(String.format("%.1f", finalDistance));
                        TripsCalendarInfo.datestr.add(formattedDate);
                        TripsCalendarInfo.trip_ids.add(curRecord.getString("trip_id"));
                        TripsCalendarInfo.trip_source.add("mobileapp");
                        TripsCalendarInfo.polyline.add(PolyUtil.encode(line.getPoints()));
                        TripsCalendarInfo.CanItrip();

                        float km_up = Float.parseFloat(TripsInfo.km.get(TripsInfo.userRank - 1)) + finalDistance;
                        int trip_up = Integer.parseInt(TripsInfo.trips.get(TripsInfo.userRank - 1)) + 1;
                        TripsInfo.trips.set(TripsInfo.userRank - 1, "" + trip_up);
                        TripsInfo.km.set(TripsInfo.userRank - 1, String.format("%.1f", km_up));
                        TripsInfo.rankSort();

                        getloc = false;

                        Intent myIntent = new Intent(Map.this, Profile.class);
                        startActivity(myIntent);

                    } catch (Exception e) {
                        Toast.makeText(getBaseContext(), "Error upload, please check your options at gear button", Toast.LENGTH_LONG).show();
                    }
                }
            });
    float finalDistance = (float) (distance / 1000.0);
    if (finalDistance < 2) {
        builder.setMessage("Your trip is below 2km and it will not be counted.\nAre you sure you want to stop?");
    }
    AlertDialog alert = builder.create();
    alert.show();

}


public void StartAct(View v) {
    timer.setVisibility(View.VISIBLE);
    dis.setVisibility(View.VISIBLE);
    newActB.setVisibility(View.GONE);
    stopActB.setVisibility(View.VISIBLE);
    //gearMap.setVisibility(View.GONE);
    navigationView.setVisibility(View.GONE);
    //headerView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_HIDE_NAVIGATION);
    toolbar.setNavigationIcon(null);          // to hide Navigation icon
    //toolbar.setDisplayHomeAsUpEnabled(false);
    handler = new Handler();

    Date currentTime = Calendar.getInstance().getTime();
    SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd%20HH:mm:ss");
    dateActStart = df.format(currentTime);
    StartTime = SystemClock.uptimeMillis();
    handler.postDelayed(runnable, 0);

    startService(new Intent(this, LocationService.class));
    //enabledActivity = true;
}

public void ChangeAct(View v) {
    if (newActL.getVisibility() == View.GONE) {
        newActL.setVisibility(View.VISIBLE);
        startActL.setVisibility(View.GONE);
    } else {
        newActL.setVisibility(View.GONE);
        startActL.setVisibility(View.VISIBLE);
    }
}

public Runnable runnable = new Runnable() {

    public void run() {

        MillisecondTime = SystemClock.uptimeMillis() - StartTime;

        UpdateTime = TimeBuff + MillisecondTime;

        Seconds = (int) (UpdateTime / 1000);

        Minutes = Seconds / 60;

        Hours = Minutes / 60;

        Seconds = Seconds % 60;

        Minutes = Minutes % 60;

        MilliSeconds = (int) (UpdateTime % 100);

        timer.setText("Time: " + String.format("%02d", Hours) + ":"
                + String.format("%02d", Minutes) + ":"
                + String.format("%02d", Seconds));

        handler.postDelayed(this, 950);
    }

};

@Override
public void onMapReady(GoogleMap map) {
    GMap = map;
    GMap.moveCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(49.8117806, 15.6970293), 6.0f));
    if (!getloc)
        getLocation();
}

Answer 1

I haven't looked through your code extensively, but have you made sure that you call the methods to get the location on your activity's onResume instead? Coming back from the background your activity's onCreate is not getting called, hence your getLocation() method is not invoked.