What are Dispatchers and name all of them? - Android Interview Questions | Android Engineers

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KotlinIntermediate4 min

What are Dispatchers and name all of them?

Answer

Dispatchers determine which thread or thread pool a coroutine runs on.

Dispatchers.Main
- Thread: The main (UI) thread.
- Use for: UI updates, handling user interactions.
Dispatchers.IO
- Thread: A shared pool of on-demand threads (64 or more).
- Use for: Blocking I/O operations (Network, Database, File reading/writing).
Dispatchers.Default
- Thread: A shared pool of threads optimized for CPU work (size = number of CPU cores).
- Use for: CPU-intensive tasks (Sorting lists, parsing JSON, complex calculations).
Dispatchers.Unconfined
- Thread: Starts in the current thread, but resumes in whatever thread the suspending function finished on.
- Use for: Testing or very specific edge cases. rarely used in general app code.

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