Vidar Vestnes Vidar Vestnes - 1 year ago 152
Android Question

How to check internet access on Android? InetAddress never times out

I got a

that is supposed to check the network access to a host name. But the
is never timed out. Anyone have a clue?

public class HostAvailabilityTask extends AsyncTask<String, Void, Boolean> {

private Main main;

public HostAvailabilityTask(Main main) {
this.main = main;

protected Boolean doInBackground(String... params) {
Main.Log("doInBackground() isHostAvailable():"+params[0]);

try {
return InetAddress.getByName(params[0]).isReachable(30);
} catch (UnknownHostException e) {
} catch (IOException e) {
return false;

protected void onPostExecute(Boolean... result) {

if(result[0] == false) {


gar gar
Answer Source

@Eddie. Just a minor edit to your solution - if the device is in airplane mode (or presumably in other situations where there's no available network), cm.getActiveNetworkInfo() will be null, so you need to add a null check.

Modified solution below:

public boolean isOnline() {
    ConnectivityManager cm =
        (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo netInfo = cm.getActiveNetworkInfo();
    return netInfo != null && netInfo.isConnectedOrConnecting();

Also add the following permission to the AndroidManifest.xml:

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

One other small point, if you absolutely need a network connection at the given point in time, then it might be better to use netInfo.isConnected() rather than netInfo.isConnectedOrConnecting. I guess this is up to the indivudal use-case however.

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