Pattern Matching

It is a generalization of C or Java’s switch statement. This matching method is used instead of a switch statement. It is defined in Scala’s root class Any and therefore is available for all objects. The match method takes a number of cases as an argument. Each alternative takes a pattern and one or more expressions that will be performed if the pattern matches. A symbol => is used to separate the pattern from the expressions.

Enroll yourself in Online Scala and Apache Spark training and give a head-start to your career in Scala!

Watch this Apache-Spark-Scala video

Pattern Matching and Case Classes Pattern Matching It is a generalization of C or Java’s switch statement. This matching method is used instead of a switch statement. It is defined in Scala’s root class Any and therefore is available for all objects. The match method takes a number of cases as an argument. Each alternative

e.g.

object Intellipaat {
def main(args: Array[String]) {
println(matchValue(2))
}
def matchValue(i: Int): String = i match {
case 1 => "one"
case 2 => "two"
case 3=> "three"
case _=> "unknown"
}
}

Output
two
If patterns are of a different type in different cases the use Any except Int and String in the above example.

Wish to get certified in Scala! Learn Scala from top Scala experts and excel in your career with Intellipaat’s Scala certification!

Case Classes
These are the special types of classes that are used for pattern matching with case expressions. By adding a case keyword there is the number of advantages which are:

  • The compiler automatically changes the constructor arguments into immutable fields.
  • The compiler automatically includes equals, hashCode and toString methods to the class

Still, have queries? Come to Intellipaat’s Big Data Community, clarify all your doubts, and excel in your career!


Syntax

case class Calculator(Value: Type)

Check out the top Apache Spark and Scala Interview Questions to learn what is expected from Apache Spark and Scala professionals!

e.g.

object Intellipaat {
def main(args: Array[String]) {
val a = new employee(1, “abc”)
val b  = new employee(2, “xyz”)
val c  = new employee(3, “pgr”)
for (employee <- List(a, b, c)) {
employee match {
case employee(1, “abc”) => println("Hello abc")
case employee(2, “xyz”) => println(“Hello xyz”)
case employee(id, employee_name) => println("ID: " +id + ", Employee:" + employee_name)
}
}
}
case class employee(id: Int, employee_name: String) // case class
}

Output
Hello abc
Hello xyz
ID: 3, Employee: pqr

Interested in learning Scala? Click here to learn more in this Scala Training in Toronto!

Recommended Videos

Leave a Reply

Your email address will not be published. Required fields are marked *