What replaces class variables in scala?

Question

In Java I sometimes use class variables to assign a unique ID to each new instance. I do something like

public class         


        

Answer 1

To amplify on Thomas' answer:

The object definition is usually put in the same file with the class, and must have the same name. This results in a single instance of an object having the name of the class, which contains whatever fields you define for it.

A handy do-it-yourself Singleton construction kit, in other words.

At the JVM level, the object definition actually results in the definition of a new class; I think it's the same name with a $ appended, e.g. Foo$. Just in case you have to interoperate some of this stuff with Java.

Answer 2

Variables on the companion object:

object Foo{
    private var current = 0
    private def inc = {current += 1; current}
}

class Foo{
    val i = Foo.inc
    println(i)
}