Taming Complex State in Jetpack Compose: ViewModel + StateFlow in a Real-World Android Screen

Short summary

A practical tutorial on managing complex UI state in Jetpack Compose using the Unidirectional Data Flow pattern with ViewModel and StateFlow. Walks through a real production map-based routing screen, showing how to model all screen state as a single immutable data class, wire it into a ViewModel that survives configuration changes, and let composables observe it for predictable, testable, recomposition-safe UI.

• •Consolidate screen state into one immutable data class exposed via StateFlow in a ViewModel
• •State flows down, events flow up — the UDF pattern prevents scattered state and unnecessary recompositions
• •Real-world map routing screen example with actual Kotlin code, not contrived counter demos

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