AbstractFlow
Base class for stateful implementations of Flow. It tracks all the properties required for context preservation and throws an IllegalStateException if any of the properties are violated.
Example of the implementation:
// list.asFlow() + collect counter
class CountingListFlow(private val values: List<Int>) : AbstractFlow<Int>() {
private val collectedCounter = AtomicInteger(0)
override suspend fun collectSafely(collector: FlowCollector<Int>) {
collectedCounter.incrementAndGet() // Increment collected counter
values.forEach { // Emit all the values
collector.emit(it)
}
}
fun toDiagnosticString(): String = "Flow with values $values was collected ${collectedCounter.value} times"
}Constructors
Functions
Extensions
Returns a flow which checks cancellation status on each emission and throws the corresponding cancellation cause if flow collector was cancelled. Note that flow builder and all implementations of SharedFlow are cancellable by default.
Catches exceptions in the flow completion and calls a specified action with the caught exception. This operator is transparent to exceptions that occur in downstream flow and does not catch exceptions that are thrown to cancel the flow.
Terminal flow operator that collects the given flow with a provided action that takes the index of an element (zero-based) and the element. If any exception occurs during collect or in the provided flow, this exception is rethrown from this method.
Returns flow where all subsequent repetitions of the same value are filtered out.
Returns flow where all subsequent repetitions of the same value are filtered out, when compared with each other via the provided areEquivalent function.
Returns flow where all subsequent repetitions of the same key are filtered out, where key is extracted with keySelector function.
The terminal operator that returns the first element emitted by the flow and then cancels flow's collection. Throws NoSuchElementException if the flow was empty.
The terminal operator that returns the first element emitted by the flow matching the given predicate and then cancels flow's collection. Throws NoSuchElementException if the flow has not contained elements matching the predicate.
The terminal operator that returns the first element emitted by the flow and then cancels flow's collection. Returns null if the flow was empty.
Returns a flow that switches to a new flow produced by transform function every time the original flow emits a value. When the original flow emits a new value, the previous flow produced by transform block is cancelled.
Flattens the given flow of flows into a single flow in a sequential manner, without interleaving nested flows.
Flattens the given flow of flows into a single flow with a concurrency limit on the number of concurrently collected flows.
The terminal operator that returns the last element emitted by the flow or null if the flow was empty.
Terminal flow operator that launches the collection of the given flow in the scope. It is a shorthand for scope.launch { flow.collect() }.
Creates a produce coroutine that collects the given flow.
Retries collection of the given flow when an exception occurs in the upstream flow and the predicate returns true. The predicate also receives an attempt number as parameter, starting from zero on the initial call. This operator is transparent to exceptions that occur in downstream flow and does not retry on exceptions that are thrown to cancel the flow.
Converts a coldFlow into a hotSharedFlow that is started in the given coroutine scope, sharing emissions from a single running instance of the upstream flow with multiple downstream subscribers, and replaying a specified number of replay values to new subscribers. See the SharedFlow documentation for the general concepts of shared flows.
The terminal operator that awaits for one and only one value to be emitted. Throws NoSuchElementException for empty flow and IllegalStateException for flow that contains more than one element.
The terminal operator that awaits for one and only one value to be emitted. Returns the single value or null, if the flow was empty or emitted more than one value.
Converts a coldFlow into a hotStateFlow that is started in the given coroutine scope, sharing the most recently emitted value from a single running instance of the upstream flow with multiple downstream subscribers. See the StateFlow documentation for the general concepts of state flows.
Starts the upstream flow in a given scope, suspends until the first value is emitted, and returns a hotStateFlow of future emissions, sharing the most recently emitted value from this running instance of the upstream flow with multiple downstream subscribers. See the StateFlow documentation for the general concepts of state flows.
Collects given flow into a destination
Collects given flow into a destination
Collects given flow into a destination
Returns a flow that produces element by transform function every time the original flow emits a value. When the original flow emits a new value, the previous transform block is cancelled, thus the name transformLatest.
Returns a flow that wraps each element into IndexedValue, containing value and its index (starting from zero).