How to Avoid Slow RecyclerView Inflation when Using Nested RecyclerViews in Android

Описание: Discover effective strategies to resolve slow `RecyclerView` inflation issues when nesting `RecyclerViews` within each other in Android development.
---
This video is based on the question https://stackoverflow.com/q/63365747/ asked by the user 'Ofek' ( https://stackoverflow.com/u/12691708/ ) and on the answer https://stackoverflow.com/a/63402259/ provided by the user 'Ofek' ( https://stackoverflow.com/u/12691708/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Android studio RecyclerView onCreateViewHolder layout inflation is so slow

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding the Problem: Slow Inflation of Nested RecyclerViews

If you've ever implemented a RecyclerView within another RecyclerView in your Android application, you might have encountered performance issues, particularly slow layout inflation times. This issue becomes apparent when you see inflated items taking far more time than expected, such as 1200 ms to load 300 rows. This significant delay can perplex any developer, especially when transitioning from a faster list implementation using ListView.

The objective of nesting RecyclerViews often includes creating a well-structured layout with section headers and details, merely to find out that the overhead costs are hindering performance. Understanding why this happens and knowing effective solutions can save you a lot of headaches.

The Cause: Overhead of Nested RecyclerViews

When you implement a RecyclerView inside another RecyclerView, the onCreateViewHolder method is called multiple times, equivalent to the size of your items array. This repeated invocation introduces heavy overhead, making layout inflation particularly sluggish—similar to how nesting a ScrollView can lead to performance issues. Thus, the use of a nested RecyclerView may not be the best design choice.

Solution 1: Use a Single Multi-View Type RecyclerView Adapter

Instead of using two separate RecyclerViews, consider creating one adapter that can handle multiple view types efficiently. This approach condenses the layout into a single RecyclerView where you can define different types for headers and main rows. Here’s how to implement this:

Step-by-step Implementation

Declare your View Types:

[[See Video to Reveal this Text or Code Snippet]]

Override getItemViewType:
In this method, you specify which type of view corresponds to each item:

[[See Video to Reveal this Text or Code Snippet]]

Handle View Inflation in onCreateViewHolder:
Depending on the view type, you will decide which layout to inflate.

[[See Video to Reveal this Text or Code Snippet]]

Create Separate ViewHolder Classes:
Have distinct ViewHolder classes for each view type to manage headers and items effectively.

Solution 2: Simplified Approach for Small Sections

If your project consists of only a few sections (around 2-3), and if flexibility isn’t a priority, consider hardcoding these sections. For instance:

You can statically create several headers followed by their respective RecyclerViews directly in your layout file.

This hands-off approach will perform well but limits future scalability.

Conclusion

In conclusion, nesting RecyclerViews can lead to poor performance due to the overuse of the onCreateViewHolder method. Adopting a single, multi-view type adapter or hardcoding small sections can dramatically improve your app's responsiveness and speed. By applying these strategies, not only can you enhance your user experience, but you'll also simplify your code structure.

Implement these solutions, and you'll likely find that you can achieve a smooth and efficient layout with flexible data presentation without compromising performance.

Happy coding!