Scala : Option Some None Example

Scala : Option Some None Example

Examples for Option..Some..None
-----------------------------------

// Simple Example
scala> def menu(day:String): Option[String] = {
     | day match {
     | case "Sunday" => Some("Fish Curry")
     | case "Monday" => Some("Veg Curry")
     | case none => None
     | }

     | }

menu: (day: String)Option[String]

scala> val foodItem = menu("Monday")

foodItem: Option[String] = Some(Veg Curry)

scala> val foodItem = menu("Sunday").getOrElse("General Food")

foodItem: String = Fish Curry

scala> val foodItem = menu("Monday").getOrElse("General Food")

foodItem: String = Veg Curry

scala> val foodItem = menu("Tuesday").getOrElse("General Food")

foodItem: String = General Food





// Regex Pattern Matching Example

scala> import scala.util.matching.Regex

import scala.util.matching.Regex

scala> val np = new Regex("[0-9]+")

np: scala.util.matching.Regex = [0-9]+

scala> val address = "1024, Vana IT Services"

address: String = 1024, Vana IT Services

scala> val match1 = np.findFirstIn(address)

match1: Option[String] = Some(1024)

scala> val address2 = "Pradham Gardenia"

address2: String = Pradham Gardenia

scala> val match2 = np.findFirstIn(address2)

match2: Option[String] = None

scala> val match1 = np.findFirstIn(address).getOrElse("No House Number found")

match1: String = 1024

scala> val match1 = np.findFirstIn(address2).getOrElse("No House Number found")

match1: String = No House Number found



// Extract numbers from a List and calcualte the sum
scala> def toInt(s:String):Option[Int] ={
     | try{
     | Some(s.toInt)
     | }
     | catch {
     | case e: Exception => None
     | }

     | }

toInt: (s: String)Option[Int]

scala> println(toInt("1").getOrElse(0))
1

scala> println(toInt("a").getOrElse(0))
0

scala> val l1 = List("1","2","Lion","4","Tiger")
l1: List[String] = List(1, 2, Lion, 4, Tiger)

scala> val sum = l1.flatMap(toInt).sum
sum: Int = 7

// class example #1
package com.spark.learning

class Person(firstName:String, lastName:String, email:Option[String]){
  var myemail = email
  def displayOutput = {
    println("First Name : " +  firstName)
    println("Last Name : " + lastName)
    println("Email : " + myemail.getOrElse("No Email"))
  }
}

object OptionSomeNoneExa extends App {
  val p = new Person("Super","Star",None)
  p.displayOutput

  p.myemail = Some("test@test.com")
  p.displayOutput
}


Result:
-------
First Name : Super
Last Name : Star
Email : No Email

First Name : Super
Last Name : Star
Email : test@test.com


// class example #2
package com.spark.learning
case class Address(city:String, state:String, country:String)
class UserInfo(emailID:String, phone:String) {
  var firstName = None: Option[String]
  var lastName = None: Option[String]
  var address = None: Option[Address]
}

object Test extends App {
  var u = new UserInfo("test@test.com","9886177375")
  u.firstName = Some("Sankara ")
  u.lastName = Some("Narayanan")
  u.address = Some(Address("Pallathur","TamilNadu","India"))

  println(s"First Name is : ${u.firstName.getOrElse("First Name Not found")}")
  println(s"Last Name is : ${u.lastName.getOrElse("Last Name Not found")}")

  u.address.foreach { x =>
    println("City is : " +  x.city)
    println("State is : " + x.state)
    println("Country is : " + x.country)
  }


    u = new UserInfo("try@test.com","9886177374")

  u.address = Some(Address("Pallathur","","India"))

  println(s" First Name is : ${u.firstName.getOrElse("First Name Not found")}")
  println(s" Last Name is : ${u.lastName.getOrElse("Last Name Not found")}")

  u.address.foreach { x =>
    println("City is : " +  x.city)
    println("State is : " + x.state)
    println("Country is : " + x.country)
  }
}

Result:
--------

First Name is : Sankara
Last Name is : Narayanan
City is : Pallathur
State is : TamilNadu
Country is : India


First Name is : First Name Not found
Last Name is : Last Name Not found
City is : Pallathur
State is :
Country is : India