java - How to get current location within a Google Maps Fragment in a ViewPager with TabLayout

Question

I managed to implement a TabLayout. Within one of the tabs is a Google Maps Fragment. I want to ask permission to access the user's location and then place a marker on the current location. As of right now, the dialog box does not show up and I do not know why. Can anyone help me?

public class MapsFragment extends Fragment implements OnMapReadyCallback{

    GoogleMap mGoogleMap;
    MapView mMapView;
    View mView;
    LocationManager locationManager;
    static final int REQUEST_LOCATION = 1;

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

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

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState){
        super.onViewCreated(view, savedInstanceState);
        mMapView = (MapView) mView.findViewById(R.id.googleMap);
        if(mMapView != null){
            mMapView.onCreate(null);
            mMapView.onResume();
            mMapView.getMapAsync(this);

        }
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        mGoogleMap = googleMap;
        googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
        //Initialize Google PLay Services
        if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M){
            if(ContextCompat.checkSelfPermission(getContext(),
                    Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED){
                //Location Permission is gratned
                MapsInitializer.initialize(getContext());
                mGoogleMap.setMyLocationEnabled(true);
            }
        }
        googleMap.addMarker(new MarkerOptions().position(new LatLng(36.652527, -121.797277)).title("CSUMB"));
        CameraPosition CSUMB = CameraPosition.builder().target(new LatLng(36.6538, -121.797277)).zoom(16).bearing(0).tilt(45).build();
        googleMap.moveCamera(CameraUpdateFactory.newCameraPosition(CSUMB));
    }

    void getLocation(){
        locationManager = (LocationManager)getActivity()
                .getSystemService(Context.LOCATION_SERVICE);
        getLocation();
        if(ActivityCompat.checkSelfPermission(getContext(), Manifest.permission.ACCESS_FINE_LOCATION)
                != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getContext(),
                Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED){

        }else{
            Location location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
            if(location!= null){
                double latti = location.getLatitude();
                double longi = location.getLongitude();
                Toast.makeText(getActivity(),"Location is " + String.valueOf(latti) + ", " + String.valueOf(longi),Toast.LENGTH_LONG);
                Log.e("Maps Fragment", "Location is: " + String.valueOf(latti) + ", " + String.valueOf(longi));
            }
            else{
                Log.e("Maps fragment", "Unable to find current location.");
            }
        }
    }
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);

        switch (requestCode) {
            case REQUEST_LOCATION:
                getLocation();
                break;
        }
    }
    @Override
    public void onResume() {
        super.onResume();
        mMapView.onResume();
    }

    @Override
    public void onPause() {
        super.onPause();
        mMapView.onPause();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        mMapView.onDestroy();
    }

    @Override
    public void onLowMemory() {
        super.onLowMemory();
        mMapView.onLowMemory();
    }
}

Answer 1

This is very close to my other answer here, however, that answer doesn't explain how to do it using a ViewPager with a TabLayout.

First, the piece that sets this apart from the other answer, you'll need to keep a reference to the current Fragment in the FragmentPagerAdapter using the instantiateItem() override.

Also, note that the onRequestPermissionsResult() method is needed here in the Activity in order to route the user's permission request response to the Fragment.

Here is the full Activity code:

public class MainActivity extends AppCompatActivity {

    ViewPager viewPager;
    PagerAdapter pagerAdapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        // Get the ViewPager and set it's PagerAdapter so that it can display items
        viewPager = (ViewPager) findViewById(R.id.viewpager);
        pagerAdapter = new PagerAdapter(getSupportFragmentManager(), MainActivity.this);
        viewPager.setAdapter(pagerAdapter);

        // Give the TabLayout the ViewPager
        TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
        tabLayout.setupWithViewPager(viewPager);

        // Iterate over all tabs and set the custom view
        for (int i = 0; i < tabLayout.getTabCount(); i++) {
            TabLayout.Tab tab = tabLayout.getTabAt(i);
            tab.setCustomView(pagerAdapter.getTabView(i));
        }
    }

    class PagerAdapter extends FragmentPagerAdapter {

        String tabTitles[] = new String[] { "Tab One", "Tab Two", "Tab Three", };
        public Fragment[] fragments = new Fragment[tabTitles.length];
        Context context;

        public PagerAdapter(FragmentManager fm, Context context) {
            super(fm);
            this.context = context;
        }

        @Override
        public int getCount() {
            return tabTitles.length;
        }

        @Override
        public Fragment getItem(int position) {

            switch (position) {
                case 0:
                    return new MapFragment();
                case 1:
                    return new BlankFragment();
                case 2:
                    return new BlankFragment();
            }

            return null;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            // Generate title based on item position
            return tabTitles[position];
        }

        public View getTabView(int position) {
            View tab = LayoutInflater.from(MainActivity.this).inflate(R.layout.custom_tab, null);
            TextView tv = (TextView) tab.findViewById(R.id.custom_text);
            tv.setText(tabTitles[position]);
            return tab;
        }

        //This populates your Fragment reference array:
        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            Fragment createdFragment = (Fragment) super.instantiateItem(container, position);
            fragments[position]  = createdFragment;
            return createdFragment;
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode,
                                           String permissions[], int[] grantResults) {
        if (requestCode == MapFragment.MY_PERMISSIONS_REQUEST_LOCATION){
            MapFragment mapFragment = (MapFragment) pagerAdapter.fragments[0];
            if (mapFragment != null) {
                mapFragment.onRequestPermissionsResult(requestCode, permissions, grantResults);
            }
        }
        else {
            super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        }
    }
}

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context=".MainActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay"
        android:elevation="6dp">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
            android:elevation="0dp" />

        <android.support.design.widget.TabLayout
            android:id="@+id/tab_layout"
            app:tabMode="fixed"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@+id/toolbar"
            android:background="?attr/colorPrimary"
            android:elevation="0dp"
            app:tabTextColor="#d3d3d3"
            app:tabSelectedTextColor="#ffffff"
            app:tabIndicatorColor="#ff00ff"
            android:minHeight="?attr/actionBarSize"
            />

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="fill_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        />

</android.support.design.widget.CoordinatorLayout>

custom_tab.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:id="@+id/custom_text"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:background="?attr/selectableItemBackground"
        android:gravity="center"
        android:textSize="16dip"
        android:textColor="#ffffff"
        android:maxLines="1"
        />
</LinearLayout>

For the Map Fragment, use essentially the same code as the other answer:

public class MapFragment extends SupportMapFragment
        implements OnMapReadyCallback,
        GoogleApiClient.ConnectionCallbacks,
        GoogleApiClient.OnConnectionFailedListener,
        LocationListener {

    GoogleMap mGoogleMap;
    LocationRequest mLocationRequest;
    GoogleApiClient mGoogleApiClient;
    Location mLastLocation;
    Marker mCurrLocationMarker;

    @Override
    public void onResume() {
        super.onResume();

        setUpMapIfNeeded();
    }

    private void setUpMapIfNeeded() {

        if (mGoogleMap == null) {
            getMapAsync(this);
        }
    }
    @Override
    public void onPause() {
        super.onPause();

        //stop location updates when Activity is no longer active
        if (mGoogleApiClient != null) {
            LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
        }
    }

    @Override
    public void onMapReady(GoogleMap googleMap)
    {
        mGoogleMap=googleMap;
        mGoogleMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);

        //Initialize Google Play Services
        if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (ContextCompat.checkSelfPermission(getActivity(),
                    Manifest.permission.ACCESS_FINE_LOCATION)
                    == PackageManager.PERMISSION_GRANTED) {
                //Location Permission already granted
                buildGoogleApiClient();
                mGoogleMap.setMyLocationEnabled(true);
            } else {
                //Request Location Permission
                checkLocationPermission();
            }
        }
        else {
            buildGoogleApiClient();
            mGoogleMap.setMyLocationEnabled(true);
        }
    }

    protected synchronized void buildGoogleApiClient() {
        mGoogleApiClient = new GoogleApiClient.Builder(getActivity())
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
        mGoogleApiClient.connect();
    }

    @Override
    public void onConnected(Bundle bundle) {
        mLocationRequest = new LocationRequest();
        mLocationRequest.setInterval(1000);
        mLocationRequest.setFastestInterval(1000);
        mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
        if (ContextCompat.checkSelfPermission(getActivity(),
                Manifest.permission.ACCESS_FINE_LOCATION)
                == PackageManager.PERMISSION_GRANTED) {
            LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
        }
    }

    @Override
    public void onConnectionSuspended(int i) {}

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {}

    @Override
    public void onLocationChanged(Location location)
    {
        mLastLocation = location;
        if (mCurrLocationMarker != null) {
            mCurrLocationMarker.remove();
        }

        //Place current location marker
        LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
        MarkerOptions markerOptions = new MarkerOptions();
        markerOptions.position(latLng);
        markerOptions.title("Current Position");
        markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_MAGENTA));
        mCurrLocationMarker = mGoogleMap.addMarker(markerOptions);

        //move map camera
        mGoogleMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
        mGoogleMap.animateCamera(CameraUpdateFactory.zoomTo(11));

        //optionally, stop location updates if only current location is needed
        if (mGoogleApiClient != null) {
            LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
        }
    }

    public static final int MY_PERMISSIONS_REQUEST_LOCATION = 99;
    private void checkLocationPermission() {
        if (ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_FINE_LOCATION)
                != PackageManager.PERMISSION_GRANTED) {

            // Should we show an explanation?
            if (ActivityCompat.shouldShowRequestPermissionRationale(getActivity(),
                    Manifest.permission.ACCESS_FINE_LOCATION)) {

                // Show an explanation to the user *asynchronously* -- don't block
                // this thread waiting for the user's response! After the user
                // sees the explanation, try again to request the permission.
                new AlertDialog.Builder(getActivity())
                        .setTitle("Location Permission Needed")
                        .setMessage("This app needs the Location permission, please accept to use location functionality")
                        .s