How are exceptions handled in coroutines using CoroutineExceptionHandler?

In Kotlin coroutines, the CoroutineExceptionHandler interface is used for handling unhandled exceptions. It is a special contextual element that can be added to the coroutine context. If an exception occurs within a coroutine that is not caught inside the coroutine itself (for example, in a try-catch block), the CoroutineExceptionHandler intercepts this exception and allows for centralized handling.

Example of usage:

val handler = CoroutineExceptionHandler { _, exception ->
    println("Caught exception: ${exception.localizedMessage}")
}

GlobalScope.launch(handler) {
    throw RuntimeException("Error in coroutine")
}

It is important to remember that CoroutineExceptionHandler only works with coroutines launched via launch, as async returns a Deferred, and exceptions from it should be handled via await.

Thus, CoroutineExceptionHandler allows centralized handling of unhandled exceptions in coroutines, preventing application crashes and providing a convenient mechanism for logging or recovery.