How can users add markers by clicking on google maps android?

Question

I am a beginner in Android programming. I already looked at similar questions and answers but I still can't figure out why this doesn't work. When I try this on the emulator and click a location, no marker appears. This is my code:

public class MapActivity extends AppCompatActivity implements LocationListener, OnMapReadyCallback, GoogleMap.OnMapClickListener {

    private MapFragment mapFragment;
    private GoogleMap googleMap;
    LocationManager locationManager;
    ArrayList<LocationProvider> providers;
    private boolean isUpdatePosition;


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

        this.isUpdatePosition = true;
        FragmentManager fragmentManager = getFragmentManager();
        mapFragment = (MapFragment) fragmentManager.findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);

    } // End onCreate

    private void mapDisplayPosition(){
        if ( ContextCompat.checkSelfPermission( this, android.Manifest.permission.ACCESS_FINE_LOCATION ) == PackageManager.PERMISSION_GRANTED ) {
            this.googleMap.setMyLocationEnabled(true);

            locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
            List<String> names = locationManager.getProviders(true);

            providers = new ArrayList<LocationProvider>();
            for(String name : names)
                providers.add(locationManager.getProvider(name));

            Criteria critere = new Criteria();

            // Pour indiquer la précision voulue
            // On peut mettre ACCURACY_FINE pour une haute précision ou ACCURACY_COARSE pour une moins bonne précision
            critere.setAccuracy(Criteria.ACCURACY_FINE);

            // Est-ce que le fournisseur doit être capable de donner une altitude ?
            critere.setAltitudeRequired(true);

            // Est-ce que le fournisseur doit être capable de donner une direction ?
            critere.setBearingRequired(true);

            // Est-ce que le fournisseur peut être payant ?
            critere.setCostAllowed(false);

            // Pour indiquer la consommation d'énergie demandée
            // Criteria.POWER_HIGH pour une haute consommation, Criteria.POWER_MEDIUM pour une consommation moyenne et Criteria.POWER_LOW pour une basse consommation
            critere.setPowerRequirement(Criteria.POWER_HIGH);

            // Est-ce que le fournisseur doit être capable de donner une vitesse ?
            critere.setSpeedRequired(true);

            locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 6000, 0, this);
            locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 6000, 0, this);
        }
    }

    @Override
    public void onLocationChanged(Location location) {
        LatLng latLng = new LatLng(location.getLatitude(),location.getLongitude());
        float zoom = 15;




        MarkerOptions markerOptions = new MarkerOptions();

        markerOptions.position(latLng);
        markerOptions.title(latLng.latitude + " : " + latLng.longitude);
        googleMap.clear();
        if(this.isUpdatePosition){
            googleMap.animateCamera(CameraUpdateFactory.newLatLng(latLng));
            this.isUpdatePosition = false;
        }

        googleMap.addMarker(markerOptions);

    }

    @Override
    public void onStatusChanged(String s, int i, Bundle bundle) {

    }

    @Override
    public void onProviderEnabled(String s) {

    }

    @Override
    public void onProviderDisabled(String s) {

    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        this.googleMap = googleMap;

        if ( ContextCompat.checkSelfPermission( this, android.Manifest.permission.ACCESS_FINE_LOCATION ) != PackageManager.PERMISSION_GRANTED ) {
            ActivityCompat.requestPermissions( this, new String[] {  android.Manifest.permission.ACCESS_FINE_LOCATION  }, 2);
        }
        mapDisplayPosition();



    }


    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);

        mapDisplayPosition();
    }

    @Override
    public void onMapClick(LatLng latLng) {

    }
}

Answer 1

You need to call setOnMapClickListener to use the OnMapClickListener on your map:

this.googleMap.setOnMapClickListener(this);

Add it to the onMapReady function like this:

@Override
public void onMapReady(GoogleMap googleMap) {
    this.googleMap = googleMap;

    if (ContextCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION}, 2);
    }

    this.googleMap.setOnMapClickListener(this);

    mapDisplayPosition();
}

Then add a marker in the onMapClick function as follows:

@Override
public void onMapClick(LatLng latLng) {
    MarkerOptions marker = new MarkerOptions()
            .position(latLng);
    this.googleMap.addMarker(marker);
}

Now you should be able to place markers when clicking anywhere on your map. However, notice that you are clearing your map in the onLocationChanged function through this line:

googleMap.clear();

Which makes the new markers disappear within seconds. Assuming this is not intended behavior, fix this by commenting it out, i.e. //googleMap.clear();.

Hope this helps! :)