Steps

1. How to initialize a Sequence of donuts

The code below shows how to create a Sequence of type String to represent a donut collection.

println("Step 1: How to initialize a Sequence of donuts")
val donuts: Seq[String] = List("Plain Donut", "Strawberry Donut", "Glazed Donut")
println(s"Elements of donuts = $donuts")

You should see the following output when you run your Scala application in IntelliJ:

Step 1: How to initialize a Sequence of donuts
Elements of donuts = List(Plain Donut, Strawberry Donut, Glazed Donut)

2. How to filter elements using the withFilter function

In the Learn How To Use Filter Function tutorial, we showed how to make use of the filter() method to restrict collection elements by the given predicate function which is passed-through the filter() method.

When using the filter() method though a new collection is created with the filtered elements. If you would prefer to avoid the overhead of the new collection, you can make use of the withFilter() method to also restrict collection elements based on a given predicate.

In the example below, we are indeed using the withFilter() method to only look for donut names which start with the character P.

println("\nStep 2: How to filter elements using the withFilter function")
 donuts
 .withFilter(_.charAt(0) == 'P')
 .foreach(donut => println(s"Donut starting with letter P = $donut"))

You should see the following output when you run your Scala application in IntelliJ:

Step 2: How to filter elements using the withFilter function
Donut starting with letter P = Plain Donut