Expandable ListView is not being made

Well here I am doing a program that takes data from a website and the target in an expandable ListView, I am getting this data and I have everything organized, the ArrayList "courses" is the Array that contains the titles of the main Array and Faculty_main is an ArrayList that contains the various sub-arrays. But the problem is that the Expandable ListView is not being done.

Here is the code:

MainActivity.java

public class MainActivity extends AppCompatActivity {

    ArrayList<String> faculades = new ArrayList<String>();
    ArrayList<ArrayList<String>> faculades_main = new ArrayList<ArrayList<String>>();
    ArrayList<String> curso = new ArrayList<String>();
    HashMap<String, List<String>> listDataChild;

    private ExpandableListView ExlistView ;
    List<String> listDataHeader;




    ExpandableListAdapter listAdapter;


    private TextView text;

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

        ExlistView = (ExpandableListView) findViewById(R.id.ExpandableList);


        Thread thread = new Thread(new Runnable() {

            @Override
            public void run() {
                try  {
                    String site1 = "http://www.dges.gov.pt/guias/indcurso.asp?letra=";
                    Document document;

                    Elements lista;

                    document = Jsoup.connect(site1 +"A").get();

                    Elements boxes = document.select("div.box10");

                    for (Element box : boxes) {

                        String linAreaC1 = box.select(".lin-area-c1").text();
                        String linAreaC2 = box.select(".lin-area-c2").text();
                        String linAreaC3 = box.select(".lin-area-c3").text();

                        curso.add(linAreaC2);
                        Log.d("tag","runned");


                        Element linCurso = box.nextElementSibling();

                        while (linCurso.hasClass("lin-curso")) {
                            String linCursoC2 = linCurso.select(".lin-curso-c2").text();
                            String linCursoC3 = linCurso.select(".lin-curso-c3").text();
                            String linCursoC4 = linCurso.select(".lin-curso-c4").text();


                            faculades.add(linCursoC3);

                            linCurso = linCurso.nextElementSibling();
                        }
                        faculades_main.add(faculades);
                        faculades = new ArrayList<String>();
                    }


                    for(int contador=0;contador<curso.size();contador++){
                }



                } catch (Exception e) {
                    e.printStackTrace();
                }
                prepareListData();
            }
        });

        thread.start();


        listAdapter = new ExpandableListAdapter(MainActivity.this, curso, listDataChild);

        ExlistView.setAdapter(listAdapter);






    }
    private void prepareListData() {
        listDataChild = new HashMap<String, List<String>>();





        for(int contador2=0;contador2<curso.size();contador2++){
        listDataChild.put(curso.get(contador2),faculades_main.get(contador2));
        }
        Log.d("tag",""+listDataChild);
    }

}

ExpandableListAdapter.java

public class ExpandableListAdapter extends BaseExpandableListAdapter {

    private Context _context;
    private List<String> _listDataHeader; // header titles
    // child data in format of header title, child title
    private HashMap<String, List<String>> _listDataChild;

    public ExpandableListAdapter(Context context, List<String> listDataHeader,
                                 HashMap<String, List<String>> listChildData) {
        this._context = context;
        this._listDataHeader = listDataHeader;
        this._listDataChild = listChildData;
    }

    @Override
    public Object getChild(int groupPosition, int childPosititon) {
        return this._listDataChild.get(this._listDataHeader.get(groupPosition))
                .get(childPosititon);
    }

    @Override
    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }

    @Override
    public View getChildView(int groupPosition, final int childPosition,
                             boolean isLastChild, View convertView, ViewGroup parent) {

        final String childText = (String) getChild(groupPosition, childPosition);

        if (convertView == null) {
            LayoutInflater infalInflater = (LayoutInflater) this._context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = infalInflater.inflate(R.layout.list_item, null);
        }

        TextView txtListChild = (TextView) convertView
                .findViewById(R.id.lblListItem);

        txtListChild.setText(childText);
        return convertView;
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        return this._listDataChild.get(this._listDataHeader.get(groupPosition))
                .size();
    }

    @Override
    public Object getGroup(int groupPosition) {
        return this._listDataHeader.get(groupPosition);
    }

    @Override
    public int getGroupCount() {
        return this._listDataHeader.size();
    }

    @Override
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded,
                             View convertView, ViewGroup parent) {
        String headerTitle = (String) getGroup(groupPosition);
        if (convertView == null) {
            LayoutInflater infalInflater = (LayoutInflater) this._context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = infalInflater.inflate(R.layout.list_group, null);
        }

        TextView lblListHeader = (TextView) convertView
                .findViewById(R.id.lblListHeader);
        lblListHeader.setTypeface(null, Typeface.BOLD);
        lblListHeader.setText(headerTitle);

        return convertView;
    }

    @Override
    public boolean hasStableIds() {
        return false;
    }

    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }
}

I have already confirmed and the HashMap listDataChild is correct and with all the data.