This repository contains code for the following tutorial on Youtube: Kotlin Coroutine Jobs (Beginner Example)
private lateinit var job: CompletableJob //allows us to invoke complete() on the job to terminate/complete the job without relying on coroutines to do so (More Control)We can get a callback when the job is completed or cancelled using the below method:
job.invokeOnCompletion {
//handler exception will pass a message which might be null or empty
it?.message.let {
var msg= it
if(msg.isNullOrEmpty()){
msg = "Unknown cancellation error."
}
println("${job} was cancelled. Reason: $msg")
}
} CoroutineScope(IO + job).launch {
//this will launch a coroutine that belongs to the IO dispatcher attached to a job
//so we can monitor its state (Complete, activte, cancelled,cancelling...)
} CoroutineScope(IO).launch {
//this will launch a coroutine that belongs to the IO dispatcher)
}The difference in the above is the following:
val coroutineScope = CoroutineScope(IO)
coroutineScope.cancel()// will cancel all coroutines that belong to the IO dispatcher
val coroutineScope = CoroutineScope(IO+job)
job.cancel()//will cancel only that job, all coroutines attached to that jobWe can get the state of coroutines attached to a job using the following method:
- job.isActive //true if job is still active
- job.isCompleted //true if job is completed
- job.isCanceled //true if job is canceled
job.cancel(CancellationException("Any Message")) //this exception will be caught by invokeOnCompletion callbackWhen a job is canceled it cannot be used again, we have to reinitialize a new job to launch more coroutines..
