Dealing with nulls

Nulls are unavoidable, especially if you work with Java libraries or get data from a database. We've already discussed that there are different ways to check whether a variable contains null in Kotlin; for example:

// Will return "String" half of the time and null the other 
// half 
val stringOrNull: String? = if (Random.nextBoolean()) 
  "String" else null  
 
// Java-way check 
if (stringOrNull != null) { 
    println(stringOrNull.length) 
}

We could rewrite this code using the Elvis operator (?:):

val alwaysLength = stringOrNull?.length ?: 0 

If the length is not null, this operator will return its value. Otherwise, it will return the default value we supplied, which is 0 in this case.

If you have a nested object, you can chain those checks. For example, let's have a Response object that contains a Profile, which, in turn, contains the first name and last name fields, which...