How to add marker on google maps android?

Look here in Google Maps example https://developers.google.com/maps/documentation/android-api/marker

If you want to add marker when clicking you can also look here: http://wptrafficanalyzer.in/blog/adding-marker-on-touched-location-of-google-maps-using-android-api-v2-with-supportmapfragment/

The concept is to do like the folowing code:

// Setting a click event handler for the map
    googleMap.setOnMapClickListener(new OnMapClickListener() {

        @Override
        public void onMapClick(LatLng latLng) {

            // Creating a marker
            MarkerOptions markerOptions = new MarkerOptions();

            // Setting the position for the marker
            markerOptions.position(latLng);

            // Setting the title for the marker.
            // This will be displayed on taping the marker
            markerOptions.title(latLng.latitude + " : " + latLng.longitude);

            // Clears the previously touched position
            googleMap.clear();

            // Animating to the touched position
            googleMap.animateCamera(CameraUpdateFactory.newLatLng(latLng));

            // Placing a marker on the touched position
            googleMap.addMarker(markerOptions);
        }
    });

//Show Marker on a Location
googleMap.addMarker(new MarkerOptions().position(TIMES_SQUARE));

//Change Default Color of Marker

googleMap.addMarker(new MarkerOptions()
            .position(BROOKLYN_BRIDGE)
            .title("First Pit Stop")
            .icon(BitmapDescriptorFactory
            .defaultMarker(BitmapDescriptorFactory.HUE_GREEN)));

//Replace Default Marker Icon with Custom Image

googleMap.addMarker(new MarkerOptions()
            .position(WALL_STREET)
            .title("Wrong Turn!")
            .icon(BitmapDescriptorFactory
            .fromResource(R.drawable.my_flag)));