getChild() method makes error

Question

I have expandable list view in my application. Data is stored in this way:

    ArrayList<Map<String, String>> groupData;   
    ArrayList<Map<String, String>> childDataItem;
    ArrayList<ArrayList<Map<String, String>>> childData;    
    Map<String, String> m;

When i use method getChild() :

    @Override
    public Object getChild(int groupPosition, int childPosititon) {
        return this.childData.get(groupData.get(groupPosition)).get(childPosititon);
    }

It makes error in groupData.get(groupPosition))

How to solve it?

Answer 1

You are misunderstanding something - arraylist works with integer position key

so -> groupData.get(groupPosition) returns String then you can't do childData.get(groupData.get(groupPosition))

Also you should consider a list like that =>

HashMap<String,<Map<String, String>> values;

here you have parent/child with only one list.

Answer 2

HashMap<String,<Map<String, String>> values;

with that :

@Override
public Object getChild(int groupPosition, int childPosititon) {
    String key = values.keyset().get(groupPosition); //Father key look how words hashmap on oracle site;
    parentElement = values.get(key);
    childKey = parentElement.keyset().get(childPosititon);
    return parentElement.get(childKey)
}

I have not factorized code to let you understand how it works. Take a look as i said, at how workds list/Map/Set. It is really important and will help you to do a cleaner code.