Kotlin Null Safety Null Coalescing / Elvis Operator
Example
Sometimes it is desirable to evaluate a nullable expression in an if-else fashion. The elvis operator, ?:, can be used in Kotlin for such a situation.
For instance:
val value: String = data?.first() ?: "Nothing here."
The expression above returns "Nothing here" if data?.first() or data itself yield a null value else the result of data?.first().
It is also possible to throw exceptions using the same syntax to abort code execution.
val value: String = data?.second()
?: throw IllegalArgumentException("Value can't be null!")
Reminder: NullPointerExceptions can be thrown using the assertion operator (e.g.
data!!.second()!!)
