We have defined chatMessage as nullable. Check out the declaration here:
private var chatMessage: String? = null
Kotlin is, by default, null safe. This means that, in Kotlin, objects cannot be null. So, if you want any object that can be null, you need to explicitly states that it can be nullable. With the safe call operator ?., we can write if(obj !=null) in the easiest way ever. The if (chatMessage?.isNotBlank() == true) can only be true if it's not null, and does not contain any whitespace. We do know how to use the Elvis operator while dealing with null. With the help of the Elvis operator, we can provide an alternative value if the object is null. We have used this feature in our code in a number of places. The following ...
