Learning Concurrency in Kotlin

Calling next() without validating for elements

When obtaining elements from an iterator using next(), it's recommended to always call hasNext() first. Failing to validate that there's an element to retrieve will result in NoSuchElementExceptions during execution, for example:

val iterator = buildIterator {    yield(1)}println(iterator.next())println(iterator.next())

This iterator can only yield one value. Because next() is being called without validating the element, an exception will be thrown: