Scala: Silently catch all exceptions

Question

Empty catch block seems to be invalid in Scala

try {
  func()
} catch {

} // error: illegal start of simple expression

How I can catch all

Answer 1

Just for a sake of completeness, there is a set of built-in methods in Exception, including silently catching exceptions. See Using scala.util.control.Exception for details on usage.

Answer 2

What about:

import scala.util.control.Exception.catching
catching(classOf[Any]) opt {func()}

It generates an Option like in some of the previous answers.

Answer 3

Inside of Scala's catch block you need to use similar construct as in a match statement:

try {
  func()
} catch {
  case _: Throwable => // Catching all exceptions and not doing anything with them
}

Answer 4

I like one of the suggestions here to use Try() with toOption, but in case you don't want to go further with Option, you can just do:

Try(func()) match {
  case Success(answer) => continue(answer)
  case Failure(e) => //do nothing
}

Answer 5

If annotating with Throwable is burdensome, you can also

scala> def quietly[A]: PartialFunction[Throwable, A] = { case _ => null.asInstanceOf[A] }
quietly: [A]=> PartialFunction[Throwable,A]

scala> val x: String = try { ??? } catch quietly
x: String = null

which has the small virtual of being self-documenting.

scala> val y = try { throw new NullPointerException ; () } catch quietly
y: Unit = ()

Answer 6

Some exceptions really aren't meant to be caught. You can request it anyway:

try { f(x) }
catch { case _: Throwable => }

but that's maybe not so safe.

All the safe exceptions are matched by scala.util.control.NonFatal, so you can:

import scala.util.control.NonFatal
try { f(x) }
catch { case NonFatal(t) => }

for a slightly less risky but still very useful catch.

Or scala.util.Try can do it for you:

Try { f(x) }

and you can pattern match on the result if you want to know what happened. (Try doesn't work so well when you want a finally block, however.)