DiffUtil

Intro

DiffUtil is a utility class by Google that calculates the difference between two lists and outputs a list of update operations that converts the first list into the second one.

Problem

Say, we use room database. Now we add one item to room which has previous n items. So after adding it should reflect in recycler view. Now, what recycler view does is that it renders all items.

This is a performance issue.

Solution

Solution in using DiffUtil. Now, the only added items will render. Say there were 3 previous item and then we add 3 more items, then code will only be called by these 3 new items i.e. the onBindViewHolder will be called only for these new added items.

There are 2 ways 2 implement Diff Utils:

1. Recycler View Adpater

• We have to implement Diff Util.

2. List Adapter

• By default Diff Util is implemented.
• Automatically use Diff Util, execute difference in background.

Both are implemented in the code. For 1 check ProgrammingListAdapter and for 2 check ProgrammingRecyclerViewAdapter.

Happy coding 👨‍💻

Demo