How does notifyDataSetChanged work?

Question

I have a question on how notifyDataSetChanged() works in a BaseExpandableListAdapter

I am updating a boolean variable, the output of which determines the output of getChildrenCount() but the number of comments visible does not change on calling it

Code:

buttonViewComments.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                allCommentsVisible = !allCommentsVisible;
                notifyDataSetChanged();
            }
        });

getChildrenCount:

public int getChildrenCount(int groupPosition) {
        if(allCommentsVisible || postList.get(groupPosition).commentListSize()<=3)
            return postList.get(groupPosition).commentListSize();
        else{
            return 3;
        }
    }

There is no data change is your adapter. Please provide "allCommentsVisiable" values inside data adapter. — Pritesh Patel, Oct 11 '17 at 12:57
Currently it is a private memeber variable of "public class PostListAdapter extends BaseExpandableListAdapter" — Meet Taraviya, Oct 11 '17 at 12:58
Other memebers: private List postList; private Context context; private String SessionID; — Meet Taraviya, Oct 11 '17 at 12:59
You will get usefull information from this link. https://stackoverflow.com/questions/12229817/android-how-does-notifydatasetchanged-method-and-listviews-work — Ghulam Moinul Quadir, Oct 11 '17 at 13:00

score 0 · Answer 1 · answered Oct 11 '17 at 12:59

notifyDataSetChanged

Notifies the attached observers that the underlying data has been changed and any View reflecting the data set should refresh itself. Reference

And in your case, there isn't any underlying data changes. In order to make it work you need to change your list postList items so it will update the set and the counter will be updated along with the size of the set.

score 0 · Answer 2 · answered Oct 11 '17 at 13:01

0

You will get some useful information about this from this link.

Android. How does notifyDataSetChanged() method and ListViews work?

answered Oct 11 '17 at 13:01

Ghulam Moinul Quadir

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How does notifyDataSetChanged work?

2 Answers2