Found following solution working for my similar problem:
private ExtendedHashMap mData = new ExtendedHashMap();
private String[] mKeys;
public void setNewData(ExtendedHashMap data) {
mData.putAll(data);
mKeys = data.keySet().toArray(new String[data.size()]);
notifyDataSetChanged();
}
Using the clear-command
mData.clear()
is not nessescary