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.
Related
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 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.
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 have the following Scala class, I am able to run it from command line
by first typing sbt then in sbt mode. But I am not able to run it from eclipse .
I am already in scala perspective.
> run-main bcomposes.twitter.QuerySearch #IPL
package bcomposes.twitter
import twitter4j._
import collection.JavaConversions._
/**
* Gets a Twitter instance set up and ready to use.
*/
trait TwitterInstance {
val twitter = new TwitterFactory().getInstance
}
/**
* Given a command line query, search for tweets and print
* them.
*/
object QuerySearch extends TwitterInstance {
def main(args: Array[String]) {
val statuses = twitter.search(new Query(args(0))).getTweets
statuses.foreach(status => println(status.getText + "\n"))
}
}
Make sure the package name you specified under which your scala object file is added matches the package name you mentioned in your code. So, correct this and then check, "Run as Scala Application" should be available now
Your Scala file has to be a part of Scala project.
Create Scala project using Scala Project wizard, add your file to it and try again.
Try to click right button on the Scala object with main method (not on the root project element). Then the "Run as... Scala application" menu item appears.
"Run as Scala application" will show in Eclipse Scala IDE only if we extends the Scala object with 'APP' class.
Example:
package grreter
object Exp extends App{
println("Hello, New World!")
}
(Note: if you comment "extends App" then 'Run As Scala Application' will not show.)
The way I solve this problem is using maven to compile and package the project , when the maven build is correct, the "run as scala application" appear again.
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.