I have been following the getting started with IntelliJ and Scala video from JetBrains and running into two problems.
I can't get it create or start a run configuration
I don't see the scala-test library as a selection under ProjectStructure-Modules-ChooseLibraries
What I've done so far is
Install Scala, add path and environment variables
Install Scala intellij plugin
Create new project set project sdk to java 1.7 and scala home to /usr/local/share/scala-2.10.3
Create an object that extends from App with a simple write line:
The one source file object
object HelloWorld{
def main(args: Array[String]) {
println("hello")
}
}
In the video they right click on the object file and can see a selection of run, but in my case I only see run as Scala Console. I can't seem to get the debugger to work and when I try to create a run configuration as an "Application" it says the src file is "not acceptable"
I'll recommend my simple project skeleton, to get you quickly up and running with Intellij, SBT and even Eclipse setup. Hope it helps!
Related
I just created a simple helloworld scala project in Intellij. My main class is simply printing Hello World -
package xx.yy.zz
object HelloWorld{
def main(args: Array[String]): Unit = {
System.out.print("Hello World!")
}
}
My project structure
scala-test
|_src
|_main
|_scala
|_xx
|_yy
|_zz
|_HelloWorld
In the project structure settings, I have "scala" as my source folder. I am able to select my main class correctly in the application run configuration I created. So far so good. After this, when I try to run my run configuration, I get the dreaded error -
Error: Could not find or load main class xx.yy.zz.HelloWorld
At this point, I have tried all the things I could find on google like invalidating cache, reloading project, switching source folder to be "src" instead of "scala" and many others that I have lost track of by now. Please help!!
I didn't investigate the reasons for this issue but as a workaround, you can compile the project via sbt/shell sbt before running via Intellij.
I have installed the latest IntelliJ Idea vertion with the Scala plugin. I have created a SBT Scala project with the IDE.
Unfortunately, I am not able to compile or run even the simplest "Hello World" example.
object Main {
def main(args: Array[String]): Unit ={
val x: Int = 5
println("Hello Scala!")
println(x)
}
}
If I try to run it, it says that "Error: could not find main class Main".
Rebuilding the project does not help.
BUT, if I run the "sbt" terminal program and execute "run", everything runs fine. Even more, it compiles the necessary class file so that IntelliJ Idea is able to run it after this step.
But, whenever I change something in the code and try to rebuild it from Idea, it will fail as before.
Edit: in Eclipse everything runs ok.
UPDATE
If I try executing "compile" from the sbt shell and then "Run" with the IDE, it will work. But, it will not do it while executing "Build" or "Rebuild Project". Sometimes, but unfortunately not always sp as to be able to reproduce it, it will throw me an exception with "Could not initialize class sbt.internal.io.Milli$"
UPDATE 2nd:
I have simplified even more the task. Now I have something like the following screenshot:
Screenshot IntelliJ IDEA
UPDATE 3rd:
There were two errors in my deployment. One of them was that, as it was pointed before, there was some package definition problems. All the source code should depend on src/main/scala, but that is not enough. So as to use the SBT structure for construction, I had to go to
File -> Settings -> Build, Execution, Deployment -> Build Tools -> sbt
and check "Use auto-import" and "use sbt shell for build and import".
After that, everything runs ok. Finall!
Thanks a lot tro everyone for the useful input!
On your screenshot Runner is in wrong package. It's written package main.scala.
If Runner.scala is in src/main/scala/way/to/my/package package declaration should be package way.to.my.package (if it's just in src/main/scala there should not be line package ...).
Also if still necessary you can try (from what should be tried first to what should be tried last, if things tried before didn't help)
sbt clean
reimport the project to IntelliJ IDEA
File -> Invalidate Caches / Restart ...
delete .idea subfolder of project folder
Did you try the green arrow near "object Main"?
This should start the program.
I am new to Scala programming and I have just started with basic programs in scala in IntelliJ IDE.
When i use the below code
package com.allaboutscala.chapter.one.tutorial_04
object HelloWorld extends App{
println("hello from hello world")
}
I wanted to see the source code of App where it uses the main method, but when i tries to see the source code and when I try to download it, I am getting error like
Sources not found: Sources for 'scala-library.jar' not found. I have attached the screenshot also.It would be great if someone could guide me here.
Since you are using sbt, you need to enable downloading of sources for your project:
open IntelliJ Preferences
search "sbt" or navigate to Preferences | Build, Execution, Deployment | Build Tools | sbt
select "Download: library sources"
refresh the sbt project
I'm trying to run a scala file with Eclipse Indigo. I have installed the Scala IDE for Eclipse and am on the Scala perspective, but the option to run as a Scala application does not appear. The file that I am currently trying to run is part of an existing project that I imported into Eclipse. The Scala IDE plugin appears to be working as I can create Scala objects and run them as Scala Applications and the Scala compiler is detecting errors.
How do I get the option to run a file as a Scala Application for the Scala IDE plugin for Eclipse Indigo?
The file you are trying to run must either be defined like this:
object MyFile extends App { /* your code to run here */ }
or:
object MyFile {
def main(args: Array[String]) { /* your code to run here */ }
}
If either of these are true, you should be able to press the play button, via right click or the toolbar at the top.
Currently I am running eclipse and play (with ~run) at the same time. When I change a file it will be compiled by play and by eclipse.
Is it possible to avoid one of those two compilation steps?
As far as I know, the eclipse plugin also uses sbt to build the project so maybe there is a way to execute the play "run" command inside eclipse?
(I am asking because my laptop is not very fast and compilation takes some time, and I would like to have the "Fast turnaround" as advertised on the play webpage ;)
You can turn off Build Automatically from the Project menu without losing any of the IDE functionality. Binaries will be built only by Sbt (on the command line).
A detailed guide for setting-up Play 2 with Scala IDE can be found on the Scala IDE website: http://scala-ide.org/docs/tutorials/play20scalaide20/index.html
I have not yet tried to run the play run sbt task in eclipse.
BUT you can run the server directly from eclipse.
Add "target/scala-2.9.1/classes" to your class path, use filters to include only your assets. (Project Properties, Java Build Path)
Choose "Run Configurations..." from the Run-Button-Menu.
Create a new "Java Application" configuration with your favourite name.
Main Tab: Use "DebugStart" as your main class
Arguments Tab: Configure any "-Dconfig.file=..." "-Dlogger.file" options you might need in VM arguments
Classpath Tab: Add the conf directory to the classpath (Advanced/Add Folders)
Create DebugStart.scala with:
import play.core.server.NettyServer
import java.io.File
import play.core.SBTLink
import play.core.TestApplication
import play.api.test.FakeApplication
import play.api.test.TestServer
object DebugStart {
def main(args: Array[String]) {
val app = FakeApplication()
val server = TestServer(9000, app)
server.start()
}
}
You can now start the app with run or debug. If you use debug, you can perform some code changes without any restart.
My version of DebugStart.scala actually contains some platform dependent hackish code to kill any running process, so that I can just hit F11 or CTRL+F11 to restart the application.
To ensure that your assets/sources are up to date run:
> sbt
...
[your project] $ ~ ;play-copy-assets;sources
IntelliJ Idea 12 (Leda) is coming soon. I'm using 11 for a while and there's no such problems but new version will offer much better Play 2.0 integration.