I am new to scala. Any help will be much appreciated.
I have created a maven project having scala files in a package in ScalaIDE editor. I want to execute main method implemented as mentioned below in one of the scala file lets say TestHelloWorld.scala
object TestHelloWorld {
def main(args: Array[String]): Unit = {
println("hey .. Hello world !!!")
}
}
I can run it from eclipse run as scala application and print statement be there on eclipse console. But I do not want to run it from IDE.
Please tell me, how should I be running this from command line in a general way, so that it gets executed?
People have suggested to run it through scala prompt "scala > ", but I want to run it from normal console.
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 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!
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.
I've been trying to get a Scala hello world example running on Eclipse using the Scala plugin. Writing the following:
package scala_test
object Test {
def main(args: Array[String]) {
println("Hello, World")
}
}
produces the following error:
<console>:1: error: eof expected but '}' found.
}
^
I've tried this on both a Windows machine and a Mac (both were using Eclipse 3.7). I've tried commenting out the function definition (just leaving an empty body for the Test object) and the error still occurs. Any ideas as to what might cause this?
You need to see output in console, not in scala interpreter.
Just right click on scala file and select "run as scala application".
Make sure you have added the Scala nature to the project. On some versions of the plugin, that option is only available from the contextual "Configuration" menu if the Scala perspective is active. Your project icon should have an "S" instead of a "J" in the corner if you have made this change.
Make sure its in the right package, runs for me. I'm using this plugin
http://scala-ide.org/