Scala example source code file (inner.scala)

This example Scala source code file (inner.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, a, b, bufferedreader, impl, int, int, io, itf, itf, itf2, javainteraction, outer3, string, string

The Scala inner.scala source code

//############################################################################
// Test Java interaction with scala inner classes
//############################################################################

import java.io.{BufferedReader, File, FileWriter, InputStreamReader}

class A {
  val abc = "A.abc"

  protected class B(x: Int, y: String) {
    println(abc); println(x)
    println(y)
  }

  trait Itf {
    def method1(x: Int): Int
    
    trait Itf2 extends Itf {
      def method2: Unit
    }
  }

  trait PlainTrait {
    def method1(x: Int): Int
  }

  class Impl(a: Int) extends Itf {
    def method1(x: Int) = {
      println(x)
      println(a)
      x + a
    }
  }

  val impl = new Impl(0)

  class Impl2 extends Impl(1) with impl.Itf2 {
    def method2 = {
      println(abc)
    }
  }

  def newImpl: Itf = new Impl(1)
  def newImpl2: Itf#Itf2 = new Impl2

  class Outer1(arg1: Int) {
    class Outer2(arg2: Int) {
      class Outer3(arg3: Int) {
        println("Outer3: " + arg1 + " " + arg2 + " " + arg3);
      }
    }
  }
}

object Scalatest {
  private val outputdir = System.getProperty("partest.output", "inner.obj")
  private val scalalib  = System.getProperty("partest.lib", "")
  private val classpath = outputdir + File.pathSeparator + scalalib
  private val javabin  = {
    val jhome = new File(System.getProperty("java.home"))
    if (jhome.getName == "jre")
      new File(jhome.getParent, "bin").getAbsolutePath
    else
      new File(jhome, "bin").getAbsolutePath
  }
  private val javacmd   = javabin + File.separator + "java"
  private val javac     = javabin + File.separator + "javac"

  def javac(src: String, fname: String) {
    val tmpfilename = outputdir + File.separator + fname
    val tmpfile = new FileWriter(tmpfilename)
    tmpfile.write(src)
    tmpfile.close
    exec(javac + " -d " + outputdir + " -classpath " + classpath + " " + tmpfilename)
  }

  def java(cname: String) =
    exec(javacmd + " -cp " + classpath + " " + cname)

  /** Execute cmd, wait for the process to end and pipe it's output to stdout */
  private def exec(cmd: String) {
    val proc = Runtime.getRuntime().exec(cmd)
    val inp = new BufferedReader(new InputStreamReader(proc.getInputStream))
    val errp = new BufferedReader(new InputStreamReader(proc.getErrorStream))
    proc.waitFor()
    while (inp.ready) println(inp.readLine())
    while (errp.ready) println(errp.readLine())
  }
}

object Test {
  def main(args: Array[String]) {
    val javaInteraction = """
public class JavaInteraction {
    public static void main(String[] args) {
        A a = new A();
        A.B b = a.new B(1, "Hello");

        A.Itf itf = a.newImpl();
        itf.method1(1);

        A.Itf.Itf2 itf2 = a.newImpl2();
        itf2.method2();

        A.Outer1 o1 = a.new Outer1(1);
        A.Outer1.Outer2 o2 = o1.new Outer2(2);
        A.Outer1.Outer2.Outer3 or = o2.new Outer3(3);
    }
}
"""
    Scalatest.javac(javaInteraction, "JavaInteraction.java")
    Scalatest.java("JavaInteraction")

    val accessingScala = """
public class AccessingScala {
    public static void main(String[] args) {
        A a = new A();
        System.out.println(a.abc());
    }
}
"""
    Scalatest.javac(accessingScala, "AccessingScala.java")
    Scalatest.java("AccessingScala")
  }
}

//############################################################################