I am having trouble understanding some code I saw ...

# getting-started

[Ellen Spertus]

I am having trouble understanding some code I saw of the form:

fun myfun: Boolean {
  return foo?.stringProperty.isNullOrEmpty()
}

It seems to me that this would return null , which is not Boolean when foo is null. Why is the above code legal?

[Sam]

Note the lack of ? before the final function call. isNullOrEmpty is an extension on a nullable type, so it can be called with a null receiver and will still return a non-null value.

[Francesc]

isNullOrEmpty is defined on a nullable type

[Francesc]

As in fun String?.fooBar() = if (this != null) foo(this) else bar()