Help with code

package apps.nathanpickard.ribbit;

import android.app.AlertDialog;
import android.os.Build;
import android.support.v4.app.NavUtils;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.util.Log;
import android.util.SparseBooleanArray;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

import com.parse.FindCallback;
import com.parse.ParseException;
import com.parse.ParseQuery;
import com.parse.ParseRelation;
import com.parse.ParseUser;

import org.w3c.dom.Text;

import java.util.List;

import butterknife.ButterKnife;
import butterknife.InjectView;


public class RecipientsActivity extends ActionBarActivity {

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

    protected List<ParseUser> mFriends;
    protected ParseRelation<ParseUser> mFriendsRelation;
    protected ParseUser mCurrentUser;

    protected MenuItem mSendMenuItem;

    @InjectView(R.id.RecipientsList) ListView mRecipientListView;
    @InjectView(R.id.empty) TextView mEmptyFriendList;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_recipients);

        ButterKnife.inject(this);

        mRecipientListView.setOnClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                if (getCheckedItemCount() > 0) {
                    mSendMenuItem.setVisible(true);
                } else {
                    mSendMenuItem.setVisible(false);
                }
            }
        });
        mRecipientListView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
    }


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

        mCurrentUser = ParseUser.getCurrentUser();
        mFriendsRelation = mCurrentUser.getRelation(ParseConstants.KEY_FRIENDS_RELATION);


        ParseQuery<ParseUser> query = mFriendsRelation.getQuery();
        query.addAscendingOrder(ParseConstants.KEY_USERNAME);

        query.findInBackground(new FindCallback<ParseUser>() {
            @Override
            public void done(List<ParseUser> friends, ParseException e) {

                if (e == null) {
                    mFriends = friends;

                    String[] usernames = new String[mFriends.size()];
                    int i = 0;
                    for (ParseUser user : mFriends) {
                        usernames[i] = user.getUsername();
                        i++;
                    }
                    ArrayAdapter<String> adapter = new ArrayAdapter<String>(
                            mRecipientListView.getContext(),
                            android.R.layout.simple_list_item_checked,
                            usernames);

                    mRecipientListView.setAdapter(adapter);
                    mRecipientListView.setEmptyView(mEmptyFriendList);

                } else {
                    Log.e(TAG, e.getMessage());
                    AlertDialog.Builder builder = new AlertDialog.Builder(RecipientsActivity.this);
                    builder.setMessage(e.getMessage())
                            .setTitle(R.string.error_title)
                            .setPositiveButton(android.R.string.ok, null);
                    AlertDialog dialog = builder.create();
                    dialog.show();
                }
            }
        });
    }

    public int getCheckedItemCount() {
        ListView listView = mRecipientListView;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            return listView.getCheckedItemCount();
        }

        SparseBooleanArray checkedItems = listView.getCheckedItemPositions();
        int count = 0;
        for (int i = 0, size = checkedItems.size(); i < size; ++i) {
            if (checkedItems.valueAt(i)) {
                count++;
            }
        }
        return count;
    }



    @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_recipients, menu);
        mSendMenuItem = menu.getItem(0);
        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.
        switch(item.getItemId()) {
            case android.R.id.home:
                NavUtils.navigateUpFromSameTask(this);
                return true;
            case R.id.action_send:
                return true;
        }
        return super.onOptionsItemSelected(item);
    }

}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                xmlns:tools="http://schemas.android.com/tools"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                tools:context=".RecipientsActivity">

    <ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/RecipientsList"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_alignParentStart="true"/>

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/empty"
        android:text="@string/empty_recipients_list_message" />

</RelativeLayout>