In what situations is it not recommended to use coroutines and RxJava?

RxJava and coroutines are not recommended for:

• Simple synchronous operations: When there is no need for asynchrony, adding complexity is unnecessary.
• Pure computations without I/O or blocking: For simple mathematical transformations or in-memory data processing, asynchrony is redundant.
• Very limited resources (especially memory): Creating and managing threads/coroutines incurs overhead, which can be critical on very weak devices (though rare in practice).
• Simple one-off tasks without need for composition: When a task runs once and does not require complex chaining or error handling in an asynchronous style.
• Beginner projects: If the team is unfamiliar with reactive or coroutine paradigms, it can slow development and increase errors. Gradual adoption is recommended.
• Small background tasks where AsyncTask or IntentService suffice (though they are deprecated): For very simple cases where complex lifecycle management or cancellation is not needed.

In most modern Android applications, using coroutines or RxJava is justified due to the need to work with network, database, and UI asynchronously. The choice of tool depends on specific tasks and team preferences.