Stuck at “Hello World” with IntelliJ IDEA 9.0.1 for Scala
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27-09-2019 - |
Question
I've been using Eclipse since 2.x and IDEs in general for over 20 years (since Turbo Pascal and Turbo C in the late '80s!).
(that preamble is supposed to imply, "I'm not an idiot" ... but doesn't sound so smart as I read it... LOL :-] )
Now I'm trying to use the Scala debugger in IntelliJ 9.0.1. I've resigned myself to an old standby, the "hello world" trick to check if the environment is setup correctly:
class hello { def main(a: Array[String]) = println("got args: " + a) }
I also tried this version, just in case:
object hello extends Application { println("hi") }
Alas, I'm unable to get even this simple Scala example to run. I'd like to eventually put a breakpoint in it, but for now just running it would be great. I have Java 1.6u20 and the Scala plug-in 0.3.473 (January 2010). The error below summarizes my experience:
What possibly could I be doing wrong?
Thanks
Solution
From your screenshot it looks like you were using:
class hello {
def main(a: Array[String]) = println("got args: " + a)
}
The main method has to be on an object to support a main method.
Capitalizing the object / class name is the convention but it isn't enforced.
OTHER TIPS
When you change your implementation from class to object, it works like a charm:
object Hello {
def main(a: Array[String]) = println("got args: " + a)
}
I picked up this little, but important difference here: http://sonyarouje.com/2011/03/18/running-scala-in-intellij-idea-10/
It may be a bug in the plugin. If you define you object as Hello (capitalized) then it works, at least on my machine.
Is your file called hello.scala
? (I can't see that it has the .scala
extension in your screenshot) - it must be a .scala
file as otherwise the compiler will not be able to compile it