title: Facebook SDK - get friends details
body: <p>I need to get friends details of the friends selected by the user.</p>
  
  <p>The user can selected his friends using default  facebook friend picker. But when I get the selection as a list of GraphUser I cannot see any details of the users. In particular, I cannot get the usernames.</p>
  
  <p>Here is the Activity of the friend picker:</p>
  
  <pre><code>public class FacebookFriendPickerActivity extends FragmentActivity {
  
  public static final String IEXTRA_SELECTED_FRIENDS = "selected friends";
  
  private FriendPickerFragment friendPickerFragment;
  
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_facebook_frind_picker);
  
      Bundle args = getIntent().getExtras();
      FragmentManager manager = getSupportFragmentManager();
      Fragment fragmentToShow = null;
  
      if (savedInstanceState == null) {
          friendPickerFragment = new FriendPickerFragment(args);
      } else {
          friendPickerFragment = (FriendPickerFragment) manager.findFragmentById(R.id.picker_fragment);
      }
      // Set the listener to handle errors
      friendPickerFragment.setOnErrorListener(new PickerFragment.OnErrorListener() {
          @Override
          public void onError(PickerFragment&lt;?&gt; fragment, FacebookException error) {
              Toast.makeText(FacebookFriendPickerActivity.this, error.getLocalizedMessage(), Toast.LENGTH_LONG).show();
              setResult(RESULT_CANCELED);
              finish();
          }
      });
      // Set the listener to handle button clicks
      friendPickerFragment.setOnDoneButtonClickedListener(new PickerFragment.OnDoneButtonClickedListener() {
          @Override
          public void onDoneButtonClicked(PickerFragment&lt;?&gt; fragment) {
              List&lt;GraphUser&gt; users = friendPickerFragment.getSelection();
              if (users.size() &gt; 0) {
                  ArrayList&lt;String&gt; usernames = new ArrayList&lt;String&gt;(users.size());
                  for (GraphUser user : users)
                      usernames.add(user.getUsername());
                  Intent data = new Intent();
                  data.putStringArrayListExtra(IEXTRA_SELECTED_FRIENDS, usernames);
                  setResult(RESULT_OK, data);
                  finish();
              } else {
                  setResult(RESULT_CANCELED);
                  finish();
              }
          }
      });
      fragmentToShow = friendPickerFragment;
      manager.beginTransaction().replace(R.id.picker_fragment, fragmentToShow).commit();
  }
  
  @Override
  protected void onStart() {
      super.onStart();
      friendPickerFragment.loadData(false);
  }
  }
  </code></pre>
  
  <p>When I try to read the list of usernames, I always get null.</p>
  
  <p>Thanks in advance.</p>