Android Access Checkbox in AdapterView

I have this second right alligned nav drawer which is filled by an adapter with checkboxes. When I change those checkboxes, the name of the the CB gets stored (or removed) in an StringSet and commited to my apps sharedPrefs. - this is working.

now i want to retrieve those Strings when the app starts and automatically check those boxes. so the user doesn't has to!

but I have absolutly no clue how to access the CheckBox...

This ist my adapter so far:

package de.timhartmann.ledcontroller;

import android.content.Context;
import android.content.SharedPreferences;
import android.preference.PreferenceManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

/**
 * Created by Tim on 02.03.2015.
 */
public class NavDrawerZonesAdapter extends BaseAdapter {
    private final ArrayList mData;
    public Set<String> selectedStrings = new HashSet<String>();

    public NavDrawerZonesAdapter(Map<String, String> map) {
        mData = new ArrayList();
        mData.addAll(map.entrySet());
    }

    @Override
    public int getCount() {
        return mData.size();
    }

    @Override
    public Map.Entry<String, String> getItem(int position) {
        return (Map.Entry) mData.get(position);
    }

    @Override
    public long getItemId(int position) {
        // TODO implement you own logic with ID
        return 0;
    }

    public void refreshList(Map<String, String> map){

        mData.clear();
        mData.addAll(map.entrySet());
        notifyDataSetChanged();

    }

    private class ViewHolder {
        TextView zone;
        TextView IP;
        CheckBox ZoneCheckBox;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        final Context context = parent.getContext();

        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
        final SharedPreferences.Editor editor = prefs.edit();

        ViewHolder viewHolder = null;

        if (convertView == null){

            LayoutInflater layoutInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = layoutInflater.inflate(R.layout.nav_drawer_zones_adapter, null);

            viewHolder = new ViewHolder();
            convertView.setTag(viewHolder);

           viewHolder.ZoneCheckBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {

               @Override
               public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {

                   if (isChecked) {
                       selectedStrings.add(buttonView.getText().toString());
                       editor.putStringSet("zones", selectedStrings).commit();
                       Toast.makeText(context, "Checkbox: " + buttonView.getText().toString(), Toast.LENGTH_LONG).show();
                   }else{
                       selectedStrings.remove(buttonView.getText().toString());
                       editor.putStringSet("zones", selectedStrings).commit();
                   }

               }

           });

        }

        else {

            viewHolder = (ViewHolder) convertView.getTag();

        }

        Map.Entry zones = (Map.Entry) mData.get(position);
        viewHolder.ZoneCheckBox.setText((CharSequence) zones.getKey());

        return convertView;
    }

}

And the Adapters Layout:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://ift.tt/nIICcg"
    android:orientation="vertical"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">

    <CheckBox
        android:id="@+id/checkBox"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:focusable="false"
        android:textSize="20dp"
        android:layout_marginTop="5dp"
        android:focusableInTouchMode="false" />

</RelativeLayout>