Scala example source code file (patterns.scala)

This example Scala source code file (patterns.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

any, boolean, int, int, john, none, none, option, option, some, some, string

The Scala patterns.scala source code

trait Option[+a] {}

case class Some[a](x: a) extends Option[a] {
  override def toString(): String = "Some(" + x + ")"
  override def equals(that: Any): Boolean = that match {
    case Some(x) => this.x == x
    case _ => false
  }
  override def hashCode(): Int = getClass().hashCode() * 41 + x.hashCode()
}

case object None extends Option[Nothing] {
  override def toString(): String = "None"
  override def equals(that: Any) = that match {
    case None => true
    case _ => false
  }
  override def hashCode(): Int = getClass().hashCode()
}

object test {

  def println(str: String): Unit = java.lang.System.out.println(str)

  def print(opt: Option[String]) = opt match {
    case Some(x) => println(x)
    case None => println("nothing")
  }
}

// if bodies are duplicated, then we would get an error like "double definition"

trait John[A,B] {
  def filter(x:Any) =    x match {
    case (x::xs, _) => "ga"
    case _ => {x:String => "foobar"}
  }
}