Kotlin Flow Cheat Sheet

import kotlinx.coroutines.flow.*import kotlinx.coroutines.*fun numbers(): Flow<Int> = flow {    for (i in 1..5) {        delay(100)          // suspend inside the builder is fine        emit(i)               // push a value downstream    }}suspend fun main() {    numbers().collect { value ->        println(value)          // 1, 2, 3, 4, 5 -- printed as they're emitted    }}// flowOf and asFlow for simple sourcesflowOf(1, 2, 3)listOf(1, 2, 3).asFlow()

numbers()    .map { it * it }    .filter { it % 2 == 0 }    .take(3)    .onEach { println("saw $it") }    .catch { e -> println("caught: $e") }     // catches upstream exceptions    .collect { println("result: $it") }// flatMapConcat / flatMapMerge / flatMapLatest for flows-of-flowssearchQuery    .debounce(300)    .flatMapLatest { query -> searchApi(query) }   // cancels previous search on new input    .collect { results -> render(results) }

fun heavyWork(): Flow<Int> = flow {    for (i in 1..5) {        Thread.sleep(50)      // pretend CPU-bound work        emit(i)    }}.flowOn(Dispatchers.Default)   // upstream (the flow{} builder) runs on Defaultsuspend fun run() {    withContext(Dispatchers.Main) {        heavyWork().collect { value ->            updateUI(value)      // collect lambda runs on Main, as expected        }    }}

class CounterViewModel : ViewModel() {    private val _count = MutableStateFlow(0)      // requires an initial value    val count: StateFlow<Int> = _count.asStateFlow()    fun increment() {        _count.update { it + 1 }        // atomic update    }}class EventBus {    private val _events = MutableSharedFlow<String>(replay = 0, extraBufferCapacity = 1)    val events: SharedFlow<String> = _events.asSharedFlow()    suspend fun publish(event: String) = _events.emit(event)}// Collecting StateFlow in Composeval count by viewModel.count.collectAsStateWithLifecycle()