What does a "?" symbol (question mark) mean in Scala?

Question

I meet some scala code with "?" but do not know what it mean in scala, could anyone explain it to me ? Thanks.

And here's one example

 def getJobId(conf: Configuration): String =
    ?(conf.get("scoobi.jobid")).getOrElse(sys.error("Scoobi job id not set."))

Answer 1

For me it looks like the apply method of Option. Is there somewhere the following import statement in the code:

import Option.{apply => ?}

This means apply is imported as ?. From the doc of Option.apply:

An Option factory which creates Some(x) if the argument is not null,
and None if it is null.

The whole statement means then:

if conf.get("scoobi.jobid") is not equal null, assign this string, otherwise assign the string sys.error("Scoobi job id not set.") returns

Answer 2

It's just a legal character, just like "abcd..."

scala> def ?(i: Int) = i > 2
$qmark: (i: Int)Boolean

scala> val a_? = ?(3)
a_?: Boolean = true

UPD: See Valid identifier characters in Scala , Scala method and values names

UPD2: In the example "?" could be function, method of this or just some object with apply method. It probably returns Option[String].