Hello World - Not working


#1

Hi,

I am new to scala and was trying to write hello world program using scala sbt.
But i am getting issue and not able to run my program. This is only happening if I am using sbt structure.
I can run program in IDEA.
Please suggest.


#2

Does SBT work from a terminal?


#3

Thanks for replying.
I tried terminal also. I am getting no main class detected.


#4

Do you have a main class?


#5

Probably best to post the full code and your full terminal interaction showing your present working dir, what you typed and errors you received.


#6

The error in the image hints at a binary incompatibility between scala versions.

What is using what, or how to fix it, I can’t tell you, unfortunately: I’m not an IDEA user myself.


#7

For beginners I recommend GUI. IDEA from JetBrains is for free.


#8

@bentito There is no code, I am just starting a new project sbt-scala. I have attached screenshot


#9

Ah, up above,
Martijn Hoekstra

, says the correct problem.

So if you follow along to get a hello world app working from command line, here: https://docs.scala-lang.org/getting-started-sbt-track/getting-started-with-scala-and-sbt-on-the-command-line.html

Once the above works, in IntelliJ File>New>Project From Existing Sources, and choose your build.sbt file. IntelliJwill, if you stick with defaults for the dialog that comes up, create a project.

But I got the same error as you about Main class not found until I changed the Project SDK back to 1.8, I had it on Java 9. You set that under the Run Configuration dialog.

Good luck, post more screen shots if you get stuck on that path, it’s a bit tricky for first few times.

-brett


#10

If there is no code, then it is to be expected that no main class is found. You need to write one.


#11

@bentito Now it ran after some hiccups. I followed your steps and i can see it running. Thank You.
But i did not got why it is not running when i am creating project directly through IDEA.


#12

If it’s working with regular sbt but not with IntelliJ, seems like that’s a bug report that should go to IntelliJ :slight_smile:


#13

Well even creating project fully inside of IntelliJ you still do have to match the Java SDK with the Scala version and most likely you chose Java 9 when 8 was the correct choice.