Declare a variable without an initial value

Question

This Scala tutorial has the following to say about declaring variables without an initial value:

If you do not assign any initial value to a variable,

Answer 1

The error is correct, you can only do that on an abstract class or trait. The tutorial might be assuming that you are writing that code inside of an abstract class.

It is possible to initialize variables to some default value:

var i: Int = _
var s: String = _

But that's essentially the same as:

var i: Int = 0
var s: String = null