Add header in ChildView from ExpandableListView (Android)

Question

I'm trying to find a solution for my answer through the Internet but I can't find a good one. I looked this topic: Android ExpandableListView Child Headers but it doesn't work for me.

What I have now (Screen):

And my code is:

private void fillData() {
    ExpandableListView lv;
    lv = (ExpandableListView) getActivity().findViewById(R.id.grades_view);
    lv.setItemsCanFocus(false);
    lv.setChoiceMode(ExpandableListView.CHOICE_MODE_SINGLE);

    View view = View.inflate(getActivity(), R.layout.list_header, null);
    lv.addHeaderView(view, null, false);

    dbh = new DatabaseHelper(getActivity());
    MyExpandableListAdapter mAdapter = new MyExpandableListAdapter(
            getActivity(), dbh);
    mAdapter.synchronize();
    lv.setAdapter(mAdapter);
    registerForContextMenu(lv);
}

public class MyExpandableListAdapter extends BaseExpandableListAdapter {

    private List<Subject> mSubjects = new ArrayList<Subject>();
    private List<List<Course>> mCourse = new ArrayList<List<Course>>();
    private DatabaseHelper dbh;
    private LayoutInflater inflater;

    public MyExpandableListAdapter(Context context, DatabaseHelper dbh) {
        this.dbh = dbh;
        this.inflater = LayoutInflater.from(context);
    }

    public void synchronize() {

        mSubjects = dbh.getSubjects();

        for (Subject s : mSubjects) {
            mCourse.add(dbh.getCourses(s));
        }
    }

    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return mCourse.get(groupPosition).get(childPosition);
    }

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

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

        Course c = (Course) getChild(groupPosition, childPosition);

        if (convertView == null)
            convertView = inflater.inflate(R.layout.list_item_child,
                    parent, false);

        TextView txt = (TextView) convertView.findViewById(R.id.code);
        txt.setText(c.getCode());
        TextView txt1 = (TextView) convertView.findViewById(R.id.ects);
        txt1.setText(String.valueOf(c.getEcts()));
        TextView txt2 = (TextView) convertView.findViewById(R.id.grade);

        if (c.getGrade() == -1) {
            txt2.setText("-");
        } else {
            txt2.setText(String.valueOf(c.getGrade()));
        }

        return convertView;
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        return mCourse.get(groupPosition).size();
    }

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

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

    @Override
    public long getGroupId(int groupPosition) {
        return mSubjects.get(groupPosition).hashCode();
    }

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded,
            View convertView, ViewGroup parent) {

        Subject s = (Subject) getGroup(groupPosition);

        if (convertView == null)
            convertView = inflater.inflate(R.layout.list_item, parent,
                    false);

        TextView txt1 = (TextView) convertView.findViewById(R.id.name);
        txt1.setText(String.valueOf(s.getName()));
        TextView txt2 = (TextView) convertView.findViewById(R.id.semester);
        txt2.setText(String.valueOf(s.getSemester()));

        return convertView;

    }

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

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

}

As we can see, to put the first-level header (Name and Sem) I used:

View view = View.inflate(getActivity(), R.layout.list_header, null);
lv.addHeaderView(view, null, false);

But I don't know how to do the same with the children (a header with Code, ECTS and Grade).

Thank you in advance.

Answer 1

Just add an "extra child"

    @Override
    public Object getChild(int groupPosition, int childPosition) {
        if (childPosition == 0)
            return null;

        return mCourse.get(groupPosition).get(childPosition - 1);
    }

    @Override
    public long getChildId(int groupPosition, int childPosition) {
        if (childPosition == 0)
            return 0;

        return getChild(groupPosition, childPosition).hashCode();
    }

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

        if (childPosition == 0) {
            convertView = inflater.inflate(R.layout.list_item_child, null);

            // your special header

            return convertView;
        } 

        // rest of your method

    }

Where you can have a different layout or whatever you like.