Android：具有不同子布局的可扩展列表视图

Question

I am trying to create an expandable listview where the last item of every list contains an EditText and the other Items containing TextViews. The code I've come up so far:

@Override
public View getChildView(int groupPosition, final int childPosition,
                         boolean isLastChild, View convertView, ViewGroup parent) {
    MainActivity.ViewHolder holder = null;
    final String childText = (String) getChild(groupPosition, childPosition);
    boolean bLastChild = childPosition == _listDataChild.get(groupPosition).size() - 1;

    if (convertView == null) {
        holder = new MainActivity.ViewHolder();
        LayoutInflater infalInflater = (LayoutInflater) this._context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        if(bLastChild) {
            convertView = infalInflater.inflate(R.layout.list_edit_item, null);
        }else {
            convertView = infalInflater.inflate(R.layout.list_item, null);
            holder.textView = (TextView) convertView.findViewById(R.id.text);
        }
        convertView.setTag(holder);
    } else {
        holder = (MainActivity.ViewHolder)convertView.getTag();
    }

    if(!bLastChild) {
        holder.textView.setText(childText);
    }

    return convertView;
}

Now I have the following Problem:

If I expand a group the first time it works. But when I collapse the group and expand it a second time the app crashes and I get the error:

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference

I guess this happens because holder.textView.setText(childText); is called when the holder refers to the layout with the EditText. But I don't know why this happens

The main idea for this code comes from here

EDIT

After some logging I found out, that the second time the group is expanded getChildView is called once for every child and then one time more at childPosition = 0 but the convertView stays the same as in the call from the last childposition:

childPosition: 0; convertView: android.widget.LinearLayout{a049868 VE..... ........ 0,157-1080,244} childPosition 1; convertView: android.widget.LinearLayout{6f19175 VE..... ........ 0,247-1080,334} childPosition 2; convertView: android.widget.LinearLayout{4aac50a VE..... ........ 0,337-1080,424} childPosition 3; convertView: android.widget.LinearLayout{47b217b VE..... ........ 0,427-1080,514} childPosition 4; convertView: android.widget.LinearLayout{cc2eb98 VE..... ........ 0,517-1080,604} childPosition 5; convertView: android.widget.LinearLayout{256cff1 VE..... ........ 0,607-1080,694} childPosition 6; convertView: android.widget.LinearLayout{7b827d6 VE..... ........ 0,697-1080,786} childPosition 0; convertView: android.widget.LinearLayout{7b827d6 VE..... ........ 0,697-1080,786}

Answer 1

Solved the problem by overriting the following two functions:

@Override
public int getChildTypeCount(){
    return 2;
}

@Override
public int getChildType(final int groupPosition, final int childPosition){
    if (childPosition == _listDataChild.get(groupPosition).size() - 1){
        return 1;
    }else{
        return 0;
    }
}