Top Android MVI libraries in 2021

Photo by Jeremy Thomas on Unsplash

When I think about MVI, the process boils down to three key concepts:

• A unidirectional cycle of data — i.e. data flows in one direction
• Processing of intents is non-blocking
• The state is immutable — outside of the Model (typically a ViewModel on Android)

Conceptually MVI is not complicated, so why use a framework when you can write your own? Watch How to write your own MVI system and why you shouldn’t, which demonstrates how to write a framework in less than 30 lines of code.

Writing an MVI style framework is not as simple as it seems:

• there are lifecycle concerns from saving state for device rotation and process death to handling side effect caching
• potential for multithreading issues
• necessary to write tests for your framework along with its multi-threaded code
• support for advanced features such as idling resource support for Espresso tests, logging, time-travel debugging and screenshot and interaction testing support