When saving in the background..app freezes before sending the message. Help please!

package com.thegreathoudini.kevin.odysity;

import android.app.AlertDialog;
import android.app.ListActivity;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.Toast;

import com.parse.FindCallback;
import com.parse.ParseException;
import com.parse.ParseFile;
import com.parse.ParseInstallation;
import com.parse.ParseObject;
import com.parse.ParsePush;
import com.parse.ParseQuery;
import com.parse.ParseRelation;
import com.parse.ParseUser;
import com.parse.SaveCallback;

import java.util.ArrayList;
import java.util.List;

public class RecipientsActivity extends ListActivity {

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

    protected ParseRelation<ParseUser> mFriendsRelations;
    protected ParseUser mCurrentUser;
    protected List<ParseUser> mFriends;
    protected ProgressBar mLoadingRecipients;
    protected MenuItem mSendMenuItem;
    protected Uri mMediaUri;
    protected String mFileType;
    protected EditText mCommentText;
    protected String mComment;

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

        getListView().setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);

        mMediaUri = getIntent().getData();
        mFileType = getIntent().getExtras().getString(ParseConstants.KEY_FILE_TYPE);
    }

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

        mCommentText = (EditText) findViewById(R.id.commentEditText);
        mLoadingRecipients = (ProgressBar) findViewById(R.id.loadingRecipientsProgress);

        mCurrentUser = ParseUser.getCurrentUser();
        mFriendsRelations = mCurrentUser.getRelation(ParseConstants.KEY_Friends_Relations);


        mLoadingRecipients.setVisibility(View.VISIBLE);
        ParseQuery<ParseUser> query = ParseUser.getQuery();
        query.orderByAscending(ParseConstants.KEY_USERNAME);
        query.setLimit(1000);
        query.setCachePolicy(ParseQuery.CachePolicy.CACHE_ELSE_NETWORK);
        query.findInBackground(new FindCallback<ParseUser>() {
            @Override
            public void done(List<ParseUser> friends, ParseException e) {
                //Build the list of Parse relations

                mLoadingRecipients.setVisibility(View.INVISIBLE);
                if (e == null) {

                    mFriends = friends;
                    String[] friendsUsername = new String[mFriends.size()];
                    int i = 0;
                    for (ParseUser friendlist : mFriends) {
                        friendsUsername[i] = friendlist.get(ParseConstants.KEY_NAME).toString();
                        i++;

                        ArrayAdapter<String> adapter = new ArrayAdapter<String>(
                                RecipientsActivity.this, android.R.layout.simple_list_item_checked, friendsUsername);
                        setListAdapter(adapter);
                    }

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

                }
            }
        });
    }

    @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.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_send) {

            mComment = mCommentText.getText().toString();

            if(mComment.isEmpty()){
                mComment = "";
            }

            mLoadingRecipients.setVisibility(View.VISIBLE);
            ParseObject message = createMessage();
            if(message == null){
                //error
                mLoadingRecipients.setVisibility(View.INVISIBLE);
                AlertDialog.Builder builder = new AlertDialog.Builder(this);
                                    builder.setMessage(R.string.error_file)
                                           .setTitle(R.string.signup_error_title)
                                           .setPositiveButton(android.R.string.ok,null);
                AlertDialog dialog = builder.create();
                dialog.show();
            }
            else {


                send(message);
                mLoadingRecipients.setVisibility(View.INVISIBLE);
                finish();
            }

            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        super.onListItemClick(l, v, position, id);

        if(l.getCheckedItemCount() > 0){
            mSendMenuItem.setVisible(true);
        }
        else {
            mSendMenuItem.setVisible(false);
        }


    }

    protected ParseObject createMessage(){

        ParseObject message = new ParseObject(ParseConstants.CLASS_MESSAGES);
                    message.put(ParseConstants.KEY_SENDERS_IDS , ParseUser.getCurrentUser().getObjectId());
                    message.put(ParseConstants.KEY_SENDER_NAME , ParseUser.getCurrentUser().getUsername());
                    message.put(ParseConstants.KEY_RECIPIENTS_IDS, getRecipientsIds());
                    message.put(ParseConstants.KEY_FILE_TYPE, mFileType);
                    message.put(ParseConstants.KEY_COMMENT_TEXT, mComment);

        byte[] fileByte = FileHelper.getByteArrayFromFile(this, mMediaUri);

        if(fileByte == null){
            return null;
        }
        else {
         if (mFileType.equals(ParseConstants.TYPE_IMAGE)){
             fileByte = FileHelper.reduceImageForUpload(fileByte);

         }
            String fileName = FileHelper.getFileName(this, mMediaUri,mFileType);
            ParseFile file = new ParseFile(fileName, fileByte);
            message.put(ParseConstants.KEY_FILE, file);

            return message;

        }


    }

    protected ArrayList<String> getRecipientsIds(){
        ArrayList<String> recipientsList = new ArrayList<>();
        for(int i = 0; i<getListView().getCount() ; i++){
            if(getListView().isItemChecked(i)){
                recipientsList.add(mFriends.get(i).getObjectId());

            }

        }
        return  recipientsList;
    }

    protected void send(ParseObject message){
        message.saveInBackground(new SaveCallback() {
            @Override
            public void done(ParseException e) {

                if (e == null) {
                    //success
                    Toast.makeText(RecipientsActivity.this, R.string.success_message, Toast.LENGTH_LONG).show();

                    sendPushNotification();


                } else {
                    AlertDialog.Builder builder = new AlertDialog.Builder(RecipientsActivity.this);
                    builder.setMessage(R.string.error_file)
                            .setTitle(R.string.signup_error_title)
                            .setPositiveButton(android.R.string.ok, null);
                    AlertDialog dialog = builder.create();
                    dialog.show();
                }

            }
        });
    }
    protected  void sendPushNotification (){
        ParseQuery<ParseInstallation> query = ParseInstallation.getQuery();
        query.whereContainedIn(ParseConstants.KEY_USER_ID, getRecipientsIds());

        //send push notification
        ParsePush push = new ParsePush();
        push.setQuery(query);
        push.setMessage(getString(R.string.push_string , ParseUser.getCurrentUser().getUsername()));

        push.sendInBackground();
    }
}