How to find if a Scala String is parseable as a Double or not?

Question

Suppose that I have a string in scala and I want to try to parse a double out of it.

I know that, I can just call toDouble and then catch the java num

Answer 1

I'd usually go with an "in place" Try:

def strTimesTen (s: String) = for (d <- Try(s.toDouble)) yield d * 10

strTimesTen("0.1") match {
    Success(d) => println( s"It is $d" )
    Failure(ex) => println( "I've asked for a number!" )
}

Note, that you can do further calculation in the for and any exception would project into a Failure(ex). AFAIK this is the idiomatic way of handling a sequence of unreliable operations.