Scala example source code file (collections.scala)

This example Scala source code file (collections.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

app, int, int, iterable, none, none, some, some, string, string, test, unit

The Scala collections.scala source code

import collection._
import scala.compat.Platform.currentTime

object Test extends App {

  val printTime = false

  def sum[A](xs: Iterable[Int]) = (0 /: xs)((x, y) => x + y)

  def time(op: => Unit) {
    val start = currentTime
    op
    if (printTime) println("  time = "+(currentTime - start)+"ms")
  }

  def test(msg: String, s0: collection.immutable.Set[Int], iters: Int) = {
    println("***** "+msg+":")
    var s = s0
    s = s + 2
    s = s + (3, 4000, 10000)
    println("test1: "+sum(s))
    time {
      s = s ++ (List.range(0, iters) map (2*))
      println("test2: "+sum(s)+", iters = "+iters)
    }
    time {
      var x = 0
      for (i <- 0 to 10000)
        if (s contains i) x += i
      println("test3: "+x)
    }
  }

  def test(msg: String, s0: collection.mutable.Set[Int], iters: Int) = {
    println("***** "+msg+":")
    var s = s0
    s = s + 2
    s = s + (3, 4000, 10000)
    println("test1: "+sum(s))
    time {
      s = s ++ (List.range(0, iters) map (2*))
      println("test2: "+sum(s)+", iters = "+iters)
    }
    time {
      var x = 0
      for (i <- 0 to 10000)
        if (s contains i) x += i
      println("test3: "+x)
    }
  }

  def test(msg: String, s0: collection.immutable.Map[Int, Int], iters: Int) = {
    println("***** "+msg+":")
    var s = s0
    s = s + (2 -> 2)
    s = s + (3 -> 3, 4000 -> 4000, 10000 -> 10000)
    println("test1: "+sum(s map (_._2)))
    time {
      s = s ++ (List.range(0, iters) map (x => x * 2 -> x * 2))
      println("test2: "+sum(s map (_._2))+", iters = "+iters)
    }
    time {
      var x = 0
      for (i <- 0 to 10000) 
        s get i match {
          case Some(i) => x += i
          case None =>
        }
      println("test3: "+x)
    }
    if (iters == 5000) {
      time {
        var s1 = s
        var x = 0
        for (i <- 0 to 10000) {
          s get i match {
            case Some(i) => x += i
            case None =>
          }
          s1 = s1 + ((i + 10000) -> i)
        }
        println("test4: "+x)
      }
    }
  }

  def test(msg: String, s0: collection.mutable.Map[Int, Int], iters: Int) = {
    println("***** "+msg+":")
    var s = s0
    s = s + (2 -> 2)
    s = s + (3 -> 3, 4000 -> 4000, 10000 -> 10000)
    println("test1: "+sum(s map (_._2)))
    time {
      s = s ++ (List.range(0, iters) map (x => x * 2 -> x * 2))
      println("test2: "+sum(s map (_._2))+", iters = "+iters)
    }
    time {
      var x = 0
      for (i <- 0 to 10000) 
        s get i match {
          case Some(i) => x += i
          case None =>
        }
      println("test3: "+x)
    }
  }

  test("mutable.HashSet", new mutable.HashSet[Int], 5000)
  test("immutable.Set", immutable.Set[Int](), 5000)
  test("immutable.ListSet", new immutable.ListSet[Int], 5000)
  test("immutable.TreeSet", new immutable.TreeSet[Int], 5000)
  test("mutable.HashMap", new mutable.HashMap[Int, Int], 5000)
  test("immutable.Map", immutable.Map[Int, Int](), 5000)
  test("immutable.TreeMap", new immutable.TreeMap[Int, Int], 5000)
  test("immutable.ListMap", new immutable.ListMap[Int, Int], 3000)
}