Question

I need to detect when the GSM phone has just been connected to the Network(from cell tower not available to cell tower connected). For this i set broadcast reciever
AIRPLANE_MODE (turns off) and BOOT_COMPLETE, when these two get fired i will loop for a while until Network is detected. But aside from this the phone might be in a location where

Cell Tower is simply not available

how can i detect such a situation?

Answer 1

You can use a BroadcastReceiver set up with an intent filter for “android.net.conn.CONNECTIVITY_CHANGE”

<receiver android:name=".ConnectivityActionReceiver">
    <intent-filter>
        <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
    </intent-filter>
</receiver>

In that receiver, you can look at the intent’s extras to figure out if you have a connection or not. I do it as follows:

@Override
public void onReceive( Context context, Intent intent )
{
    Intent startIntent;
    SharedPreferences prefs;
    String action;
    int updateType;

    action = intent.getAction();
    if ( !action.equals( ConnectivityManager.CONNECTIVITY_ACTION ) )
        return;

    /* If we don't have a connection, nothing to do */
    if ( intent.getBooleanExtra( ConnectivityManager.EXTRA_NO_CONNECTIVITY, false ) )
        return;

If that second if check is true that means there’s no network connection, so the receiver exits. Next time there’s a connectivity change, the receiver is activated again and runs this check again. Once it passes the check, then I proceed to do whatever I do.