What is Unidirectional Flow? - Android Interview Questions | Android Engineers

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KotlinIntermediate4 min

What is Unidirectional Flow?

Answer

Unidirectional Data Flow (UDF) is a design pattern where data flows in only one direction.

The Cycle

State: Flows down from the ViewModel to the UI.
Events: Flow up from the UI to the ViewModel (user actions).
Mutation: The ViewModel processes the event and updates the State.

Benefits

Predictability: State is only changed in one place.
Debuggability: Easy to trace where data changed.
Testability: UI and Logic are decoupled.

Commonly implemented using `StateFlow` or `LiveData`.

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