Future: recover vs. andThen

// Let's compare Future.recover and Future.andThen
// Try to answer these questions yourself:
// 1. what is the expected type for each future?
// 2. how many "Future1 started" lines expected in stdout?
// 3. both PartialFunctions are not exhausive; what happens if it doesn't match the case?

import java.time.LocalDateTime
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.Future
import scala.io.StdIn
import scala.language.postfixOps
import scala.util.Success

object Main extends App {
  def print(x: Any): Unit = {Thread.sleep(50); println(s"${LocalDateTime.now()}: $x")}

  def f1 = Future {
    print("Future1 started")
    Thread.sleep(5000)
    print("Future1 finished")
    5 / 2
  }

  val recoveredFuture: Future[AnyVal] = f1.recover {   // AnyVal is common type for (Int, Long)
    case ex: ArithmeticException => println(s"Divide by 0 exception: $ex"); Long.MaxValue
  }

  val sideEffectFuture: Future[Int] = f1.andThen {
    case Success(x) => println(s"Result is $x")
  }

  print("Press ENTER to finish")
  StdIn.readLine()
  print(s"Results: $recoveredFuture; $sideEffectFuture")
}

        // 1. Interrupted futures:
        // 2018-08-19T18:12:55.976: Future1 started
        // 2018-08-19T18:12:55.983: Future1 started
        // 2018-08-19T18:12:55.984: Press ENTER to finish
        //
        // 2018-08-19T18:12:57.250: Results: Future(<not completed>); Future(<not completed>)

        // 2. Successful execution:
        // 2018-08-19T18:13:07.345: Press ENTER to finish
        // 2018-08-19T18:13:07.345: Future1 started
        // 2018-08-19T18:13:07.345: Future1 started
        // 2018-08-19T18:13:12.400: Future1 finished
        // 2018-08-19T18:13:12.404: Future1 finished
        // Result is 2

        // 2018-08-19T18:13:13.328: Results: Future(Success(2)); Future(Success(2))

        // 3. Failed execution:
5 / 0
        // 2018-08-19T18:13:29.086: Future1 started
        // 2018-08-19T18:13:29.086: Future1 started
        // 2018-08-19T18:13:29.086: Press ENTER to finish
        // 2018-08-19T18:13:34.140: Future1 finished
        // 2018-08-19T18:13:34.140: Future1 finished
        // Divide by 0 exception: java.lang.ArithmeticException: / by zero
        //
        // 2018-08-19T18:13:36.240: Results: Future(Success(9223372036854775807)); Future(Failure(java.lang.ArithmeticException: / by zero))