Check network connection in fragment

Question

I tried to check the network connection in my SherlockFragment but the getSystemService() method is not recognized.

Below is my code (from http://developer.android.com/training/basics/network-ops/connecting.html)

    ConnectivityManager connMgr = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
    if (networkInfo != null && networkInfo.isConnected()) {
        // fetch data
    } else {
        // display error
    }

Thanks in advance

Solution 1

The method getSystemService() is not defined on fragments, so get the activity first using getActivity(), e.g.:

ConnectivityManager connMgr = (ConnectivityManager) getActivity()
                             .getSystemService(Context.CONNECTIVITY_SERVICE);

NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();

if (networkInfo != null && networkInfo.isConnected()) {
    // fetch data
} else {
    // display error
}

p.s: additianal note: if there is a potential risk that the fragment is running without being attached to any activity, check whether getActivity() returns null first.

Cheers!

Solution 2

The better way is to use network function code in try- catch. And catch the exception If network unavailable. If you use any network checking code, then also you need to catch the exception. Because You have no other way to check whether it is suceeded or no, means, if the network lost in between the function completes.

Comments

[Lalith Mohan]

It Worked!! Thank you so much.

[Jithu]

I was searching the same way in first time, finaly i reached in this decesition. I simply shared with you.

[Lalith Mohan]

The fragment is attached to an activity. What is the risk if not attached?

[Trinimon]

If it is not attached, getActivity() might return null and consequently getActivity().getSystemService() throws a NullPointerException. However, it depends where you call this code and how you create the fragments. Nothing to worry about, just keep it in your mind ;)

[Qadir Hussain]

@Trinimon Im getting getActivity() null. how to resolve this? In android phone Running andriod 4.0.3 its working fine. but in tablet Nexus 7 running 4.4.1 it returns null. Whats going wrong. y its happing?

[Trinimon]

If getActivity() returns null, this shows that no activity has been attached at that point of time. Did you use it in onActivityCreated() or somewhere else? Did you create the fragment solely? You can also try to move your code to the onAttach(Activity activity) method of the fragment - here you have the activity available and you don't need to call getActivity() at all.