How it works…

We have used the sortedWith function, which takes in a comparator. The comparator is provided by the compareBy function. The compareBy has an overload that takes multiple functions:

public fun <T> compareBy(vararg selectors: (T) -> Comparable<*>?):Comparator<T>

As you can see in the preceding code, vararg allows us to take multiple functions in its construct and returns a comparator, which feeds the sortedWith function.

Note that sorting with multiple fields works like sort by field 1, then by field 2, then by field 3, and so on.