Pattern Matching with Match

In this lesson, you will learn about pattern matching and how it is implemented using the `match` control structure.

We'll cover the following

Pattern Matching #

Pattern matching means exactly what you think it might—checking if an object or series of tokens match a specified pattern. A pattern match consists of a list of alternative cases which are made up of a pattern and a corresponding expression.

Using match #

In Scala, pattern matching is done using the match expression. It is evaluated by taking the object to be matched and comparing it with each pattern in the order they are listed. The first pattern to match the object expression is selected and the corresponding expression is evaluated.

Syntax #

selector is our object to be matched with the list of alternative patterns. Each case consists of a pattern followed by => which is further followed by an expression to be evaluated if its corresponding pattern is selected.

An Example #

Let’s look at an example where given a food item, match matches it to its companion food.

The code below, requires you to insert an input, the method of which has been discussed in a previous lesson.

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val food = scala.io.StdIn.readLine()
food match {
  case "fish" => println("chips")
  case "peanut butter" => println("jelly")
  case "hamburger" => println("french fries")
  case _ => println("Try a new food!")
}

Enter the input below

Pretty cool! When we give the match expression a food item, it tells us what we should pair with it. _ is known as a wildcard pattern and matches with any object.

The purpose of this lesson was to provide you the syntax for using match. You will see the true power of pattern matching when we go over the different types of patterns provided by Scala.

In the next lesson, we have a challenge for you to solve for yourself.