Question

An UnknownHostException is thrown if a server is down or if there is no internet connection. How can I determine if the UnknownHostException is thrown because the server is down or there is no internet connection?

The reason for this is I need to notify the user about the cause of the error. And I have to display something like this “Sorry. The service is currently not available. Please try again later” or “You do not have an internet connection”.

Answer 1

You could check the network state to determine if an internet connection is available (not 100% reliable though):

ConnectivityManager conMgr =  (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);

if ( conMgr.getNetworkInfo(0).getState() == NetworkInfo.State.CONNECTED 
    ||  conMgr.getNetworkInfo(1).getState() == NetworkInfo.State.CONNECTING  ) {
...
}

EDIT :

IMHO, there is no way to tell for sure that the phone internet connectivity is down.
But you could, in addition to checking the network state, make a simple test like downloading a small page from a website on the internet (pick some reliable server).

The result of this double test should be accurate 99% of the time.