Scala example source code file (Test.scala)

This example Scala source code file (Test.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

a, a2, a3, array, b, b, file, function0, int, int, net, network, structf0, structf0, test, test

The Scala Test.scala source code

import scala.tools.nsc.io._
import java.net.URL

object A { def apply(d: { def apply(): Int}) = d.apply() }
object A2 { def apply(d: { def apply(): Int}) = d.apply() }
object A3 { def apply(d: { def apply(): Int}) = d.apply() }
object A4 { def apply(d: { def apply(): Int}) = d.apply() }

class B extends Function0[Int] {
	def apply() = 3
}

object Test
{
  type StructF0 = { def apply(): Int }
	def main(args: Array[String]) {
		for(i <- 0 until 150)
			println(i + " " + test(A.apply) + " " + test(A2.apply) + " " + test(A3.apply) + " " + test(A3.apply))
	}
	
	def test(withF0: StructF0 => Int): Int = {
	  // Some large jar
	  val jar = File("../../../../lib/scalacheck.jar").toURL
	  // load a class in a separate loader that will be passed to A
	  val loader = new java.net.URLClassLoader(Array(File(".").toURL, jar))
	  // load a real class to fill perm gen space
    Class.forName("org.scalacheck.Properties", true, loader).newInstance 
    // create a class from another class loader with an apply: Int method
  	val b = Class.forName("B", true, loader).newInstance
	
		// pass instance to a, which will call apply using structural type reflection.
		// This should hold on to the class for B, which means bLoader will not get collected
	  withF0(b.asInstanceOf[StructF0])
	}
}