Ich habe eine mehrstufige ExpandableListView (3 Ebenen, Root -> Parent -> Child), die untergeordnete Elemente enthält, die auch ExpandableListViews sind. Ich habe kein Problem damit, sie zu füllen. Ich muss jedoch ein bestimmtes Element in der übergeordneten Ebene erweitern, wenn ich die Aktivität zum ersten Mal anzeige (onCreate).

Ich habe das zugehörige Stammelement des übergeordneten Elements erfolgreich erweitert, kann das übergeordnete Element jedoch anscheinend nicht erweitern. Die angegebenen Listener werden angerufen, und das Ergebnis wird in meiner Liste mit mehreren Ebenen nicht angezeigt.

Aktivität, in der ich die Erweiterung nenne:

public class Activity {
    private int groupToExpand = 4, childToExpand = 3;
    protected void onCreate(Bundle savedInstance) {
        final ExpandableListView elv = (ExpandableListView) findViewById(R.id.elv);
        if (arrayList!= null && !arrayList.isEmpty()) {
            elv.setAdapter(new RootAdapter(this, arrayList);
            // this selects the correct group, but doesn't expand the child.
            elv.setSelectedChild(groupToExpand, childToExpand, true); 
            elv.expandGroup(groupToExpand); // this works.
        }
    }
}

Mein Root-Adapter:

public class RootAdapter extends BaseExpandableListAdapter {

private List<Objects> arrayList;
private Context context;
private LayoutInflater inflater;

public RootAdapter(Context context, List<Objects> arrayList) {
    this.context = context;
    this.arrayList = arrayList;
    this.inflater = LayoutInflater.from(context);
}

@Override
public Object getChild(int groupPosition, int childPosition) {
    final Objects parent = (Objects) getGroup(groupPosition);
    return parent.arrayList.get(childPosition);
}

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

@Override
public View getChildView(int groupPosition, int childPosition,
        boolean isLastChild, View convertView, ViewGroup parent) {
    final Objects o = (Objects) getChild(groupPosition, childPosition);

    CustomExpandableListView elv = (CustomExpandableListView) convertView;
    ChildViewHolder holder;

    if (elv == null) {
        holder = new ChildViewHolder();

        elv = new CustomExpandableListView(context);
        elv.setGroupIndicator(null);
        elv.setDivider(null);
        elv.setCacheColorHint(Color.parseColor("#00000000"));
        elv.setChildDivider(null);
        elv.setChildIndicator(null);
        elv.setScrollingCacheEnabled(false);
        elv.setAnimationCacheEnabled(false);

        holder.cListView = elv;
        elv.setTag(holder);
    } else {
        holder = (ChildViewHolder) elv.getTag();
    }

    final ParentAdapter adapter = new ParentAdapter(context, o);
    holder.cListView.setAdapter(adapter);

    return elv;
}

private static class ChildViewHolder {
    CustomExpandableListView cListView;
}

@Override
public int getChildrenCount(int groupPosition) {
    final Objects parent = (Objects) getGroup(groupPosition);
    return parent.arrayList.size();
}

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

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

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

@Override
public View getGroupView(int groupPosition, boolean isExpanded,
        View convertView, ViewGroup parent) {
    View layout = convertView;
    GroupViewHolder holder;
    final Objects o = (Objects) getGroup(groupPosition);

    if (layout == null) {
        layout = inflater.inflate(R.layout.item_to_inflate, parent, false);
        holder = new GroupViewHolder();

        holder.title = (TextView) layout.findViewById(R.id.title);
        holder.image = (ImageView) layout.findViewById(R.id.image);
        layout.setTag(holder);
    } else {
        holder = (GroupViewHolder) layout.getTag();
    }

    holder.title.setText(o.title.trim());

    return layout;
}

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

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

private static class GroupViewHolder {
    TextView title;
    ImageView image;
}

public class CustomExpandableListView extends ExpandableListView {

    public CustomExpandableListView(Context context) {
        super(context);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        heightMeasureSpec = MeasureSpec.makeMeasureSpec(2000, MeasureSpec.AT_MOST);
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

}

}

Endlich mein ParentAdapter:

public class ParentAdapter extends BaseExpandableListAdapter {

private Objects child;
private LayoutInflater inflater;

public ParentAdapter(Context context, Objects child) {
    this.child = child;
    this.inflater = LayoutInflater.from(context);
}

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

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

@Override
public View getChildView(int groupPosition, int childPosition,
        boolean isLastChild, View convertView, ViewGroup parent) {
    View layout = convertView;
    final Objects o = (Objects) getChild(0, childPosition);

    ChildViewHolder holder;

    if (layout == null) {
        layout = inflater.inflate(R.layout.item_to_inflate, parent, false);

        holder = new ChildViewHolder();
        holder.title = (TextView) layout.findViewById(R.id.title);
        layout.setTag(holder);
    } else {
        holder = (ChildViewHolder) layout.getTag();
    }

    holder.title.setText(o.title.trim());

    return layout;
}

@Override
public int getChildrenCount(int groupPosition) {
    return child.arrayList.size();
}

@Override
public Object getGroup(int groupPosition) {
    return child;
}

@Override
public int getGroupCount() {
    return 1;
}

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

@Override
public View getGroupView(int groupPosition, boolean isExpanded,
        View convertView, ViewGroup parent) {
    View layout = convertView;
    GroupViewHolder holder;

    if (layout == null) {
        layout = inflater.inflate(R.layout.item_to_inflate, parent, false);
        holder = new GroupViewHolder();

        holder.image = (ImageView) layout.findViewById(R.id.image);
        holder.title = (TextView) layout.findViewById(R.id.title);
        layout.setTag(holder);  
    } else {
        holder = (GroupViewHolder) layout.getTag();
    }
    holder.title.setText(o.title.trim());

    return layout;
}

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

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

private static class GroupViewHolder {
    TextView title;
    ImageView image;
}

private static class ChildViewHolder {
    TextView title;
}

}

Ich kann die untergeordneten Listen im Stammverzeichnis ExpandableListView nicht erweitern. Kennen Sie eine korrekte Möglichkeit, die Elemente auf der Ebene der übergeordneten Elemente zu erweitern?

Ich habe in getChildView des RootAdapter versucht:

if (groupToExpand == groupPosition && childToExpand == childPosition) {
    elv.expandGroup(childToExpand);
}

Dann habe ich in der Aktivität geändert:

if (arrayList!= null && !arrayList.isEmpty()) {
    RootAdapter adapter = new RootAdapter(this, arrayList);
    elv.setAdapter(adapter);
    // this selects the correct group, but doesn't expand the child.
    elv.setSelectedChild(groupToExpand, childToExpand, true); 
    elv.expandGroup(groupToExpand); // this works.

    adapter.groupToExpand = groupToExpand;
    adapter.childToExpand = childToExpand;
    adapter.notifyDataSetChanged();
}

Dies erweitert das übergeordnete Element, ABER, es generiert doppelte Elemente des übergeordneten Elements. Wie mache ich das richtig? Ist dies der richtige Weg, aber mein Adapter ist kaputt und erzeugt daher doppelte Elemente?

Ich kann einfach nicht finden, was ich hier vermisse ...