I want to implement a locationListener which will switch between network and GPS providers based on availability.
For example if GPS is not enabled I want it to use
Sure, you just get the providers for the network and GPS and pass whichever you want to locationManager.requestLocationUpdates().
When you want to stop listening to a certain provider, call locationManager.removeUpdates() with the listener object you specified in locationManager.requestLocationUpdates().
Network:
Criteria crit = new Criteria();
crit.setPowerRequirement(Criteria.POWER_LOW);
crit.setAccuracy(Criteria.ACCURACY_COARSE);
String provider = locationManager.getBestProvider(crit, false);
GPS:
Criteria crit2 = new Criteria();
crit2.setAccuracy(Criteria.ACCURACY_FINE);
provider2 = locationManager.getBestProvider(crit2, false);
You can use LocationManager.isProviderEnabled() doc to see if the appropriate provider is enabled/disabled. There's more info available in the LocationManager docs.
GPS is usually much slower than network since you have to find 3+ far-away satellites, etc.