Chapter 4, Introduction to Kotlin

1. Yes, variables and expressions can be used inside string literals beginning with a $ sign.
2. A nullable variable/argument can be assigned null at any point of code. However, before using, defensive code must be used to check for null safety. Kotlin has reduced the chances of NullPointerException using a nullable variable/argument. An example of a nullable variable/argument is var no : Int? = 0, which uses ? at the end of the data type.
3. Explicit casting in Kotlin is where when a type checking is done using the is a keyword. Within the block of code that follows, there is no need to do a type casting to the destination type. Here is the following code:

var s : Any = "Shazin";
if (s is String) {
 // No need to cast s of type Any to type String inside this block of code like java does using ((String) s)
 // All properties and functions of String...