Scala Tutorial - Scala while Loops

The while loop executes a block of code as long as a condition is true.

The following code prints out a complaint once a day until the next Friday the 13th has arrived:

object Main {
  def main(args: Array[String]) {
     import java.util.Calendar 
     def isFridayThirteen(cal: Calendar): Boolean = { 
       val dayOfWeek = cal.get(Calendar.DAY_OF_WEEK) 
       val dayOfMonth = cal.get(Calendar.DAY_OF_MONTH) 
       (dayOfWeek == Calendar.FRIDAY) && (dayOfMonth == 13) 
     } 
     while (!isFridayThirteen(Calendar.getInstance())) { 
       println("Today isn't Friday the 13th. Lame.") 
       Thread.sleep(86400000) 
     } 
  }
}

Scala do-while Loops

A do-while loop executes some code while a conditional expression is true.

That is, the do-while checks to see if the condition is true after running the block.

To count up to 10, we could write this:

object Main {
  def main(args: Array[String]) {
     var count = 0 
     do { 
       count += 1 
       println(count) 
     } while (count < 10) 
  }
}