String pattern matching best practice

In terms of syntax, you can modify just a tiny bit you case statements:

case url if url.startsWith("jdbc:mysql:") => "com.mysql.jdbc.Driver"

This simply binds the value url to the pattern expression (which is also url) and adds a guard expression with a test. That should make the code compile.

To make it a little bit more scala-like, you can return an Option[String] (I removed a couple clause since it’s just for illustration):

def resolveDriver(url: String) = url match {
  case u if u.startsWith("jdbc:mysql:") => Some("com.mysql.jdbc.Driver")
  case u if u.startsWith("jdbc:postgresql:") => Some("org.postgresql.Driver")
  case _ => None
}

That is unless you want to manage exceptions.