Pattern Matching Scala Collections

Doesn't the title say it all?

joesan published on

2 min, 215 words

Categories: Technical Stuff

Tags: scala

One of the astonishing features that Scala has is the pattern matching mechanism. Think of it like a Java Switch statement on Steroids. Pattern matching is such a powerful concept in Scala. Once you start using them, you'll find it inevitable to not using them. Let's look at some examples

You want to pattern match a List based on the number of elements in the List :

def patternMatch = {
  val matchResult = List(1,2,3,4,5) match {
    case Nil => "Matches an empty List"
    case head :: Nil => "Matches a List that has exactly one element"
    case head :: tail => "Matches a List that hast at-least one element"
  }
}

What is happening in the above code snippet is that, the myList is run through the case blocks. It is obvious that myList has more than one element in it and hence the last case statement is matched where the following statement is returned as the matchResult.

If you are wondering what the case syntax is all about, here is a quick description of what it is:

case <i>pattern</i> => <i>expression</i>

The case is a Scala keyword, the pattern is what you specify for the supplied value to be checked against and the expression is what you want to be returned if the pattern matches. Simple or?