zoom to fit all markers on map google maps v2

Try using this

//Calculate the markers to get their position
LatLngBounds.Builder b = new LatLngBounds.Builder();
for (Marker m : markers) {
    b.include(m.getPosition());
}
LatLngBounds bounds = b.build();
//Change the padding as per needed
CameraUpdate cu = CameraUpdateFactory.newLatLngBounds(bounds, 25,25,5);
mMap.animateCamera(cu);

Check this Google Maps v2 library that i have created that includes this functionality just use

Marker m1,m2, m3, m4 .... ;

mapHelper.zoomToFitMarkers(m1,m2, m3, m4 ....);

EDIT :

Get current location

LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
//You can use GPS_PROVIDER also
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, new LocationListener() {

        @Override
        public void onStatusChanged(String provider, int status, Bundle extras) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onProviderEnabled(String provider) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onProviderDisabled(String provider) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onLocationChanged(Location location) {
            // TODO Auto-generated method stub
            currentLatitude = location.getLatitude();
            currentLongitude = location.getLongitude();
            //Add your marker here and zoom to fit it
            //mapHelper.zoomToFitMarkers(m1,m2, m3, m4,mapHelper.addMarker(currentLatitude,currentLongitude,"Current Location"););
        }
    });

mMap.moveCamera(CameraUpdateFactory.newLatLngBounds(builder.build(), 15));