About Flow

Basic Nature

• Flows are mostly cold🧊 in nature.
• Here, The flows won't start until there is a subscriber.
• Whenever a new subscriber is added to the flow, It will get all the data. The flow will start from the beginning and send all the data to the subscriber.
• If there are multiple subscribers, All see all the data from the flow.
• The subscribers are responsible for closing the flow for which it is subscribed. So there is no external control here like the way with channels.
• In channels even if there are known consumers the producers continue sending the data. But if there are no consumers, there won't be emissions.
• Each subscriber has its flow but in channels, all the subscribers share the emissions.

Cancelling flow

• We need to collect a flow in a co-routine, The co-routine has a job reference that is used to handle the coroutine
• When we cancel the job, The flow associated with the subscriber is canceled
• As we already know if there are no subscribers the flow will not be in an active state.
• Important to note that in channels when u cancel the Channel all the subscribers are cancelled but in flows, When you cancel a consumer the other consumers might not cancel and continue to execute.

 private val input = listOf(1,2,3,4,5,6,7,8,9).asFlow()
    private var jobIp : Job? = null
    fun stoppingFlowDemoStart() {
        jobIp = viewModelScope.launch {
            input.collect{
                println("CurrentElement -> $it")
                delay(1500)
            }
        }
    }

    fun invokeCancel(){
        jobIp?.let {
            it.cancel(cause = CancellationException("Cancelled by the user"))
        }
    }