Scala and Java data structures

Question

I'm new to Scala and have imported an external Java (nmap4J) library that returns an object called:

class org.nmap4j.data.nmaprun.Verbose

• How do I determine what the object type is in scala?
• How would I then convert it to something thats usable in Scala?

I'm assuming I would ned to use the Scala Java Conversions, but I'm a little confused as where to start.

http://www.scala-lang.org/api/2.10.2/index.html#scala.collection.JavaConversions

Answer 1

You can use it just like you'd use it in Java, and it's type doesn't change: it's org.nmap4j.data.nmaprun.Verbose .

Conversions and Converters are intended to transform a Java standard library collection into a Scala standard library collection and vice versa. Generally speaking, if you have a Java collection that is not from the standard library, there's likely some reason for it to be different, and converting it to Scala would defy its purpose.

Answer 2

type conversion

Lets say you have an unknown Object (scala Any / AnyRef ) and you think it is a class of Verbose:

import org.nmap4j.data.nmaprun.Verbose

def checkObj(in: Any) {
  in match {
    case v: Verbose =>
      // do something with v

    case _ =>
      // do error handling
}

This is the scala way of doing isInstanceOf / asInstanceOf . Almost always you can treat a java class like a scala class.

list conversion

If your framework gives you java collections, you import, as you said correctly, java conversions.

import scala.collection.JavaConversions._

def doSomething(list: java.util.List[Any]) {
  // map is now possible due to the implicit conversion of list
  list.map(el => doStuff(el))

  // other methods
  list.toSeq
  list.foreach(println)
}