Android share action doesn't do anything

Question

I'm following a course on Udacity on building an Android app (weather, in this case). I've been having trouble implementing a Share action. After getting some advice from another forum, I changed the min SDK version from 10 or 11 to 17, since this is just a learning activity. Currently, I have the "Share" button showing up in the action bar, but tapping on it does nothing. I tried putting it in the overflow menu, but still, nothing. I tried some debugging, but I don't know where the button click is supposed to be handled; the debugger goes through and creates the shareIntent object, but then nothing seems to happen with it. I looked at this doc, but when I try to handle the sharing in the view's onOptionsItemSelected, I get a null pointer exception on the call to createShareIntent. What am I missing?

Here's the nested fragment's onCreateOptionsMenu:

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
    inflater.inflate(R.menu.detail_fragment, menu);
    MenuItem item = menu.findItem(R.id.action_share);

    ShareActionProvider mShareActionProvider = new ShareActionProvider(getActivity());
    if(mShareActionProvider != null) {
        mShareActionProvider.setShareIntent(createShareIntent());
    } else {
        Log.d(LOG_TAG, "Share action provider is null");
    }
}

Here's the containing view's onOptionsItemSelected, with the problematic code commented out:

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        startActivity(new Intent(this, SettingsActivity.class));
        return true;
    } else if (id == R.id.action_share) {
        //DetailFragment details = (DetailFragment) getFragmentManager().findFragmentByTag("detailFragment");
        //startActivity(details.createShareIntent());
    }

    return super.onOptionsItemSelected(item);
}

And here's the createShareIntent method:

private Intent createShareIntent() {
    Intent shareIntent = new Intent(Intent.ACTION_SEND);
    shareIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
    shareIntent.setType("text/plain");
    shareIntent.putExtra(Intent.EXTRA_TEXT, mForecastStr + FORECAST_SHARE_HASHTAG);
    return shareIntent;
}

Answer 1

It turns out I had put android:actionProviderClass="android.widget.ShareActionProvider in a layout XML file instead of a menu one. I don't think the Udacity course I'm taking mentioned the correct location for that (perhaps due to compatibility things).