SharedFlow for events in Android Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is SharedFlow in Kotlin?

SharedFlow is a hot flow that allows multiple collectors to receive the same emitted values. It is useful for sharing events or data streams across different parts of an app.

intermediate

Why use SharedFlow for events instead of StateFlow?

SharedFlow is better for one-time events because it can replay a configurable number of past events and does not hold a current state like StateFlow. StateFlow always holds the latest value, which is not ideal for events.

beginner

How do you configure a SharedFlow to replay the last event for new subscribers?

You set the replay parameter when creating the SharedFlow. For example, MutableSharedFlow(replay = 1) will replay the last emitted event to new subscribers.

beginner

What does it mean that SharedFlow is a hot flow?

A hot flow means it emits values regardless of whether there are active collectors. Events are produced continuously and shared with all subscribers.

beginner

How can you emit an event using a MutableSharedFlow?

You call the emit() suspend function or tryEmit() function on the MutableSharedFlow instance to send an event to all collectors.

What parameter controls how many past events a SharedFlow replays to new subscribers?

A capacity

B bufferSize

C replay

D cacheSize

The 'replay' parameter defines how many past events are replayed to new subscribers.

Which of these is true about SharedFlow?

A It is a cold flow that starts emitting only when collected

B It is a hot flow that emits events regardless of collectors

C It holds a current state like StateFlow

D It cannot have multiple subscribers

SharedFlow is a hot flow, meaning it emits events regardless of active collectors.

Which function is used to send an event to a MutableSharedFlow?

A emit()

B collect()

C subscribe()

D launch()

The emit() suspend function is used to send events to a MutableSharedFlow.

Why is SharedFlow preferred over StateFlow for one-time events?

A SharedFlow holds the latest state

B StateFlow replays all past events

C StateFlow is not observable

D SharedFlow can replay a limited number of events without holding state

SharedFlow can replay a limited number of events and does not hold a current state, making it better for one-time events.

What happens if you collect a SharedFlow after some events have already been emitted and replay is set to 0?

A You receive no past events, only new ones

B You receive all past events

C You receive only the latest event

D The flow throws an error

With replay set to 0, new collectors receive only new events emitted after they start collecting.

Explain how SharedFlow works for event handling in Android Kotlin apps.

Think about how events are shared and replayed to subscribers.

Describe the difference between SharedFlow and StateFlow and when to use each.

Consider how each flow handles data and events.