How to capture exception stacktrace (stderr) to file in Scala - scala

Question

How can I capture the exception stacktrace into a file in Scala? I tried with System.setErr but it didn't work, while Console.withErr can be set only for a code snippet and not for the whole app. Any idea?
I would like to log to a file all the uncaught exceptions of the app
Edit:
A bit more context: I run inside a spark-shell with a jar added in the classpath. What I do is instantiating an object of a class and the first code ran inside the class is the following, which doesn't give me the
expected print
Thread.currentThread().setUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() {
def uncaughtException(t: Thread, e: Throwable): Unit = {
logger.error("exception logged")
println("exception logged")
}
})
throw new Exception("my ex")
but I don't see the print neither in stdout nor in the log file

Answer 1

Just use the Thread.setUncaughtExceptionHandler:
Java uncaught global exception handler
Use Thread.currentThread() if your app is single-threaded to get the current thread.
Edit
object ErrorHandling {
def main(args: Array[String]): Unit = {
Thread.currentThread().setUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() {
def uncaughtException(t: Thread, e: Throwable): Unit = {
// logger.error("exception logged")
println(s"exception logged: $e")
e.printStackTrace()
}
})
throw new Exception(s"boom")
}
}
Should give you something like:
exception logged: java.lang.Exception: boom
java.lang.Exception: boom
at ErrorHandling$.main(ErrorHandling.scala:10)
at ErrorHandling.main(ErrorHandling.scala)