ExpandableListView中的ListView始终显示所有项目中重复的最后一个元素

Question

当我展开ExpandableListView的项目时，我想显示一个ListView。这是ExpandableListView的适配器：

public class ExpandableListAdapterDay extends BaseExpandableListAdapter{

private Activity _context;
private ArrayList<String> _listDataHeader; // header titles
private HashMap<String, ArrayList<DataDay>> _listDataChild;

private static class ViewHolderChild {

    public final ListView listDay;

    public ViewHolderChild(ListView listDay) {
        this.listDay = listDay;
    }
}

private static class ViewHolderGroup {

    public final TextView textHeader;

    public ViewHolderGroup(TextView textHeader) {
        this.textHeader = textHeader;
    }
}

public ExpandableListAdapterDay(Activity context, ArrayList<String> listDataHeader,
        HashMap<String, ArrayList<DataDay>> listChildData) {
    this._context = context;
    this._listDataHeader = listDataHeader;
    this._listDataChild = listChildData;
}


@Override
public int getGroupCount() {
    // TODO Auto-generated method stub
    return this._listDataHeader.size();
}

@Override
public int getChildrenCount(int groupPosition) {
    // TODO Auto-generated method stub
    return this._listDataChild.get(this._listDataHeader.get(groupPosition)).size();
}

@Override
public Object getGroup(int groupPosition) {
    // TODO Auto-generated method stub
    return this._listDataHeader.get(groupPosition);
}

@Override
public Object getChild(int groupPosition, int childPosition) {
    // TODO Auto-generated method stub
    return this._listDataChild.get(this._listDataHeader.get(groupPosition));
            //.get(childPosition);
}

@Override
public long getGroupId(int groupPosition) {
    // TODO Auto-generated method stub
    return groupPosition;
}

@Override
public long getChildId(int groupPosition, int childPosition) {
    // TODO Auto-generated method stub
    return childPosition;
}

@Override
public boolean hasStableIds() {
    // TODO Auto-generated method stub
    return false;
}

@Override
public View getGroupView(int groupPosition, boolean isExpanded,
        View convertView, ViewGroup parent) {
    // TODO Auto-generated method stub

    TextView textHeader;
    String strDataHeader = (String) getGroup(groupPosition);

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

          textHeader = (TextView) convertView.findViewById(R.id.textHeaderDay);
          convertView.setTag(new ViewHolderGroup(textHeader));
    } else {
        ViewHolderGroup viewHolder = (ViewHolderGroup) convertView.getTag();

        textHeader = viewHolder.textHeader;
    }

    textHeader.setTypeface(null, Typeface.BOLD);
    textHeader.setText(strDataHeader);

    return convertView;
}

@Override
public View getChildView(int groupPosition, int childPosition,
        boolean isLastChild, View convertView, ViewGroup parent) {
    // TODO Auto-generated method stub

    ListView listDay;

    final ArrayList<DataDay> arrayDay = (ArrayList<DataDay>) getChild(groupPosition, childPosition);

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

        listDay = (ListView) convertView.findViewById(R.id.listDay);

        convertView.setTag(new ViewHolderChild(listDay));
    } else { 

        ViewHolderChild viewHolder = (ViewHolderChild) convertView.getTag();

        listDay = viewHolder.listDay;
    }

    AdapterDataDay adapter = new AdapterDataDay (_context, arrayDay);
    listDay.setAdapter(adapter);


    return convertView;

}

@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
    // TODO Auto-generated method stub
    return true;
}

}

当我展开ExpandableListView时，这是我想要显示的ListView的适配器：

public class AdapterDataDay extends BaseAdapter{

protected Context activity;
protected ArrayList<DataDay> arrayItem;

private static class ViewHolder {

    public TextView textDate;
    public TextViewEx textItem;

    public ViewHolder() {
    }
}

public AdapterDatosOraciones(Context activity, ArrayList<DataDay> items) {
    this.activity = activity;
    this.arrayItem = items;
}


@Override
public int getCount() {
    // TODO Auto-generated method stub
    return arrayItem.size();
}

@Override
public Object getItem(int arg0) {
    // TODO Auto-generated method stub
    return arrayItem.get(arg0);
}

@Override
public long getItemId(int position) {
    // TODO Auto-generated method stub
    return arrayItem.get(position).getId();
}


@SuppressLint("NewApi")
@Override
public View getView(int position, View convertView, ViewGroup arg2) {

    ViewHolder holder;

    if(convertView == null){
        LayoutInflater inf = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = inf.inflate(R.layout.list_item_day_listview, null);

        holder = new ViewHolder();

        holder.textDate = (TextView) convertView.findViewById(R.id.textDate);
        holder.textItem = (TextViewEx) convertView.findViewById(R.id.textItem);

        convertView.setTag(holder);
    } else {
        holder = (ViewHolder) convertView.getTag();
    }

    DataDay data = arrayItem.get(position);


    holder.textDate.setText(data.strDate);
    holder.textItem.setText(data.strItem, true);

    return convertView;
}

}

问题是，当我展开ExpandableListView的项目时，ListView的所有项目都是相同的，在所有ListView中始终显示相同的项目。我做错了什么？

提前致谢。