android - best practice for updating an adapter

Question

I have an adapter that displays a grid of thumbnails with a text. These thumbnails are heavy to load, heavy to draw, etc.

The thumbnail gridview is constantly filled with new content, let's say, 1 new item every 2 seconds.

My adapter has a function that I call from outside to inject new items:

public void postNew(Item i) {
    arrayStuff.put(i);
    notifyDataSetChanged();
}

What happens is, with my current approach, when I insert a new element in the gridview, it refreshes everything, even if the added item is not going to be visible. The refresh process kind of breaks the experience, specially if the user is browsing the gridview and new content arrives.

How would you recommend improving this? is there a lighter 'notifyDataSetChanged()' or something like that?

Answer 1

I do not know of any lighter version of notify data set, but you can always use ListView.getFirstVisiblePosition and ListView.getLastVisiblePosition to determine whether your latest added position is visible, and only call notifyDataSetChanged if it is.

As for "heavy" bitmaps, as heavy as it is I think you should resample or scale it to the minimum size you need, using LruCache you can reduce the need of re-drawing on notify data set changed.

Answer 2

It sounds like you probably need to implement some form of caching, it's not very good memory management to have images which are not visible loaded into memory, ideally you would retrieve them from cache when they become (or are about to become) visible.

An alternative approach could be to add some form of visual indicator when new content arrives and then implement "pull down to refresh" or similar, then make a call to notifyDataSetChanged() on your adapter to refresh the content. I can imagine that refreshing every couple of seconds would not give a great UX because it would be hard to follow if the screen content is constantly changing.

Answer 3

You need create custom view(dynamic at runtime) that adds multiple imageview and appropriate textview, the container view should be LinearLayout, after that you can able to update a particular view or element.