Question

I have an Android application which, among other things, also publishes updates on Facebook.

I created my code according to this example and it works perfectly fine. The only difference in my code and the one in the link above is that I also extended onActivityResult as mentioned on the official Facebook SDK for Android page.

    @Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    facebookClient.authorizeCallback(requestCode, resultCode, data);
}

Sometimes however, I get a null pointer exception on the line where I call the “facebook.authorizeCallback()” within the onActivityResult() method.

This has never occurred on any of my mobile phones or emulators. However, I keep getting user crash reports, mostly from Droid and T-Mobile myTouch 3G phones. I tried a lot but was unable to reproduce the problem. Any body have any idea what could be wrong ?

Answer 1

By looking in Facebook.java code it seems that the DialogListener and is kept as a private parameter in the class… when calling authorizeCallback() you assume that the DialogListener exits and isn’t null. BUT if your phone is short on memory (like my G1 is) your calling activity is killed to vacate memory for the facebook login process those erasing your DialogListener when you call the autherizeCallback function you’ll get a null pointer exception or the callback is ignored.
This might be the cause of your problem.