I am trying to display items in friends detail extra credit activity Ribbt.

public static final String TAG = FriendsDetailsActivity.class.getSimpleName();

protected TextView  mUsernameDetails;
protected TextView  mEmailDetails;
protected String mID;
protected String mUsernameText;
protected String mEmailText;

protected ParseUser mTappedOnUser;
protected ParseRelation<ParseUser> mFriendsRelations;
protected List<ParseUser> mFriends;



@[Ben Jakuben](https://teamtreehouse.com/benjakuben) Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_friends_details);
    getActionBar();

    //set variables
    mUsernameDetails = (TextView) findViewById(R.id.usernameDetails);
    mID = getIntent().getStringExtra(ParseConstants.KEY_ID); //objectID of tapped on person


}

@Override
protected void onResume() {
    super.onResume();

    mID = getIntent().getStringExtra(ParseConstants.KEY_ID); //objectID of tapped on person

    mTappedOnUser = ParseUser.getCurrentUser().getParseUser(mID);

    mFriendsRelations = mTappedOnUser.getRelation(ParseConstants.KEY_Friends_Relations);



    ParseQuery<ParseUser> query = mFriendsRelations.getQuery();
    query.findInBackground(new FindCallback<ParseUser>() {
        @Override
        public void done(List<ParseUser> detailUserFriends, ParseException e) {

            if (e == null) {
                //success
                mFriends = detailUserFriends;
                String[] detailUsernames = new String[mFriends.size()];
                int i = 0;
                for (ParseUser detailList : mFriends) {
                    detailUsernames[i] = detailList.getUsername();
                    i++;

                    ArrayAdapter<String> adapter = new ArrayAdapter<String>
                            (FriendsDetailsActivity.this, android.R.layout.simple_list_item_1, detailUsernames);
                    setListAdapter(adapter);

                }


            }


        }

    });

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_friends_details, menu);
    return true;
}

@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) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}