Introduction to Scala Part3: Option & Pattern Matching

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Methods of Option

get

Some(1).get // 1
None.get //java.util.NoSuchElementException: None.get

getOrElse

Some(1).getOrElse(2) // 1
None.getOrElse(2) // 2

Option

Option(1) // Some(1)
Option(null) // None

IsEmpty

Some(1).isEmpty // false
None.isEmpty // true

Map Option

getNameOfPerson

getNameUsingMap

getEmail

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package fp101.tp03.option
object ExerciceOptionPerson {
  /**
   *
   * email is not mandatory
   *
   */
  class Person(val name: String, val age: Int, val email: Option[String]) {
    override def toString = s"Person($name, $age, $email)"
  }
  object Person { def apply(name: String, age: Int, email: Option[String]) = new Person(name, age, email) }
  object PersonDao {
    private val persons = Map(
      1 -> Person("John Snow", 25, Some("john.snow@winterfell.we")),
      2 -> Person("Tyrion Lannister", 30, Some("theimp@CasterlyRock.we")),
      3 -> Person("Sandor Clegane", 40, None))
    def findById(id: Int): Option[Person] = persons.get(id)
    def findAll = persons.values
  }
  /**
   *
   * return the name of p otherwise "N/A"
   * using only if, else and Option methods

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2/5 Methods of Option

Methods of Option

get

getOrElse

Option

IsEmpty

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