TL;DR

The average salary of Scala ~~ was so high that I was interested in ~~, so I decided to try it, so I decided to make a project for Hello World in my spare time.

Average annual income ranking by language

Well, I'm doing installation system in various places, so it's better now.

There should be no problem if you use the most popular framework.

playframework

Well, right away.

`console`


$ activator new my-first-app play-scala

Completed without any problems (I feel like WARNING was out ...)

`console`


$ cd my-first-app/
$ activator
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by activator.ActivatorProxyAuthenticator$ (file:/Users/(username)/.sbt/boot/scala-2.11.8/com.typesafe.activator/activator-launcher/1.3.12/activator-launcher-1.3.12.jar) to field java.net.Authenticator.theAuthenticator
WARNING: Please consider reporting this to the maintainers of activator.ActivatorProxyAuthenticator$
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
error: error while loading package, Missing dependency 'object java.lang.Object in compiler mirror', required by /Users/(username)/.sbt/boot/scala-2.10.6/lib/scala-library.jar(scala/package.class)
error: error while loading package, Missing dependency 'object java.lang.Object in compiler mirror', required by /Users/(username)/.sbt/boot/scala-2.10.6/lib/scala-library.jar(scala/runtime/package.class)
scala.reflect.internal.MissingRequirementError: object java.lang.Object in compiler mirror not found.
	at scala.reflect.internal.MissingRequirementError$.signal(MissingRequirementError.scala:16)
	at scala.reflect.internal.MissingRequirementError$.notFound(MissingRequirementError.scala:17)
	at scala.reflect.internal.Mirrors$RootsBase.getModuleOrClass(Mirrors.scala:48)
	at scala.reflect.internal.Mirrors$RootsBase.getModuleOrClass(Mirrors.scala:40)
	at scala.reflect.internal.Mirrors$RootsBase.getModuleOrClass(Mirrors.scala:40)
	at scala.reflect.internal.Mirrors$RootsBase.getModuleOrClass(Mirrors.scala:61)
	at scala.reflect.internal.Mirrors$RootsBase.getClassByName(Mirrors.scala:99)
	at scala.reflect.internal.Mirrors$RootsBase.getRequiredClass(Mirrors.scala:102)
	at scala.reflect.internal.Definitions$DefinitionsClass.ObjectClass$lzycompute(Definitions.scala:264)
	at scala.reflect.internal.Definitions$DefinitionsClass.ObjectClass(Definitions.scala:264)
	at scala.reflect.internal.Definitions$DefinitionsClass.AnyRefClass$lzycompute(Definitions.scala:263)
	at scala.reflect.internal.Definitions$DefinitionsClass.AnyRefClass(Definitions.scala:263)
	at scala.reflect.internal.Definitions$DefinitionsClass.specialPolyClass(Definitions.scala:1120)
	at scala.reflect.internal.Definitions$DefinitionsClass.RepeatedParamClass$lzycompute(Definitions.scala:407)
	at scala.reflect.internal.Definitions$DefinitionsClass.RepeatedParamClass(Definitions.scala:407)
	at scala.reflect.internal.Definitions$DefinitionsClass.syntheticCoreClasses$lzycompute(Definitions.scala:1154)
	at scala.reflect.internal.Definitions$DefinitionsClass.syntheticCoreClasses(Definitions.scala:1152)
	at scala.reflect.internal.Definitions$DefinitionsClass.symbolsNotPresentInBytecode$lzycompute(Definitions.scala:1196)
	at scala.reflect.internal.Definitions$DefinitionsClass.symbolsNotPresentInBytecode(Definitions.scala:1196)
	at scala.reflect.internal.Definitions$DefinitionsClass.init(Definitions.scala:1261)
	at scala.tools.nsc.Global$Run.<init>(Global.scala:1290)
	at sbt.compiler.Eval$$anon$1.<init>(Eval.scala:141)
	at sbt.compiler.Eval.run$lzycompute$1(Eval.scala:141)
	at sbt.compiler.Eval.run$1(Eval.scala:141)
	at sbt.compiler.Eval.unlinkAll$1(Eval.scala:144)
	at sbt.compiler.Eval.evalCommon(Eval.scala:153)
	at sbt.compiler.Eval.eval(Eval.scala:96)
	at sbt.EvaluateConfigurations$.evaluateDslEntry(EvaluateConfigurations.scala:177)
	at sbt.EvaluateConfigurations$$anonfun$9.apply(EvaluateConfigurations.scala:117)
	at sbt.EvaluateConfigurations$$anonfun$9.apply(EvaluateConfigurations.scala:115)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
	at scala.collection.immutable.List.foreach(List.scala:318)
	at scala.collection.TraversableLike$class.map(TraversableLike.scala:244)
	at scala.collection.AbstractTraversable.map(Traversable.scala:105)
	at sbt.EvaluateConfigurations$.evaluateSbtFile(EvaluateConfigurations.scala:115)
	at sbt.Load$.sbt$Load$$loadSettingsFile$1(Load.scala:725)
	at sbt.Load$$anonfun$sbt$Load$$memoLoadSettingsFile$1$1.apply(Load.scala:731)
	at sbt.Load$$anonfun$sbt$Load$$memoLoadSettingsFile$1$1.apply(Load.scala:730)
	at scala.collection.MapLike$class.getOrElse(MapLike.scala:128)
	at scala.collection.AbstractMap.getOrElse(Map.scala:58)
	at sbt.Load$.sbt$Load$$memoLoadSettingsFile$1(Load.scala:730)
	at sbt.Load$$anonfun$loadFiles$1$2.apply(Load.scala:738)
	at sbt.Load$$anonfun$loadFiles$1$2.apply(Load.scala:738)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
	at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
	at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:47)
	at scala.collection.TraversableLike$class.map(TraversableLike.scala:244)
	at scala.collection.AbstractTraversable.map(Traversable.scala:105)
	at sbt.Load$.loadFiles$1(Load.scala:738)
	at sbt.Load$.discoverProjects(Load.scala:749)
	at sbt.Load$.discover$1(Load.scala:555)
	at sbt.Load$.loadTransitive(Load.scala:584)
	at sbt.Load$.loadProjects$1(Load.scala:452)
	at sbt.Load$.loadUnit(Load.scala:456)
	at sbt.Load$$anonfun$18$$anonfun$apply$11.apply(Load.scala:291)
	at sbt.Load$$anonfun$18$$anonfun$apply$11.apply(Load.scala:291)
	at sbt.BuildLoader$$anonfun$componentLoader$1$$anonfun$apply$4$$anonfun$apply$5$$anonfun$apply$6.apply(BuildLoader.scala:91)
	at sbt.BuildLoader$$anonfun$componentLoader$1$$anonfun$apply$4$$anonfun$apply$5$$anonfun$apply$6.apply(BuildLoader.scala:90)
	at sbt.BuildLoader.apply(BuildLoader.scala:140)
	at sbt.Load$.loadAll(Load.scala:344)
	at sbt.Load$.loadURI(Load.scala:299)
	at sbt.Load$.load(Load.scala:295)
	at sbt.Load$.load(Load.scala:286)
	at sbt.Load$.apply(Load.scala:140)
	at sbt.Load$.buildPluginDefinition(Load.scala:836)
	at sbt.Load$.buildPlugins(Load.scala:802)
	at sbt.Load$.plugins(Load.scala:790)
	at sbt.Load$.loadUnit(Load.scala:441)
	at sbt.Load$$anonfun$18$$anonfun$apply$11.apply(Load.scala:291)
	at sbt.Load$$anonfun$18$$anonfun$apply$11.apply(Load.scala:291)
	at sbt.BuildLoader$$anonfun$componentLoader$1$$anonfun$apply$4$$anonfun$apply$5$$anonfun$apply$6.apply(BuildLoader.scala:91)
	at sbt.BuildLoader$$anonfun$componentLoader$1$$anonfun$apply$4$$anonfun$apply$5$$anonfun$apply$6.apply(BuildLoader.scala:90)
	at sbt.BuildLoader.apply(BuildLoader.scala:140)
	at sbt.Load$.loadAll(Load.scala:344)
	at sbt.Load$.loadURI(Load.scala:299)
	at sbt.Load$.load(Load.scala:295)
	at sbt.Load$.load(Load.scala:286)
	at sbt.Load$.apply(Load.scala:140)
	at sbt.Load$.defaultLoad(Load.scala:36)
	at sbt.BuiltinCommands$.liftedTree1$1(Main.scala:492)
	at sbt.BuiltinCommands$.doLoadProject(Main.scala:492)
	at sbt.BuiltinCommands$$anonfun$loadProjectImpl$2.apply(Main.scala:484)
	at sbt.BuiltinCommands$$anonfun$loadProjectImpl$2.apply(Main.scala:484)
	at sbt.Command$$anonfun$applyEffect$1$$anonfun$apply$2.apply(Command.scala:59)
	at sbt.Command$$anonfun$applyEffect$1$$anonfun$apply$2.apply(Command.scala:59)
	at sbt.Command$$anonfun$applyEffect$2$$anonfun$apply$3.apply(Command.scala:61)
	at sbt.Command$$anonfun$applyEffect$2$$anonfun$apply$3.apply(Command.scala:61)
	at sbt.Command$.process(Command.scala:93)
	at sbt.MainLoop$$anonfun$1$$anonfun$apply$1.apply(MainLoop.scala:96)
	at sbt.MainLoop$$anonfun$1$$anonfun$apply$1.apply(MainLoop.scala:96)
	at sbt.State$$anon$1.process(State.scala:184)
	at sbt.MainLoop$$anonfun$1.apply(MainLoop.scala:96)
	at sbt.MainLoop$$anonfun$1.apply(MainLoop.scala:96)
	at sbt.ErrorHandling$.wideConvert(ErrorHandling.scala:17)
	at sbt.MainLoop$.next(MainLoop.scala:96)
	at sbt.MainLoop$.run(MainLoop.scala:89)
	at sbt.MainLoop$$anonfun$runWithNewLog$1.apply(MainLoop.scala:68)
	at sbt.MainLoop$$anonfun$runWithNewLog$1.apply(MainLoop.scala:63)
	at sbt.Using.apply(Using.scala:24)
	at sbt.MainLoop$.runWithNewLog(MainLoop.scala:63)
	at sbt.MainLoop$.runAndClearLast(MainLoop.scala:46)
	at sbt.MainLoop$.runLoggedLoop(MainLoop.scala:30)
	at sbt.MainLoop$.runLogged(MainLoop.scala:22)
	at sbt.StandardMain$.runManaged(Main.scala:54)
	at sbt.xMain.run(Main.scala:29)
	at xsbt.boot.Launch$$anonfun$run$1.apply(Launch.scala:109)
	at xsbt.boot.Launch$.withContextLoader(Launch.scala:128)
	at xsbt.boot.Launch$.run(Launch.scala:109)
	at xsbt.boot.Launch$$anonfun$apply$1.apply(Launch.scala:35)
	at xsbt.boot.Launch$.launch(Launch.scala:117)
	at xsbt.boot.Launch$.apply(Launch.scala:18)
	at xsbt.boot.Boot$.runImpl(Boot.scala:41)
	at xsbt.boot.Boot$.main(Boot.scala:17)
	at xsbt.boot.Boot.main(Boot.scala)
[error] scala.reflect.internal.MissingRequirementError: object java.lang.Object in compiler mirror not found.
[error] Use 'last' for the full log.
Project loading failed: (r)etry, (q)uit, (l)ast, or (i)gnore? q

** I didn't write that it would come out like this? ** **

It seems that the installed java (java10) is not the problem () When I googled with an error, it was hard to find because only the articles where the java.lang.Object part became scala came to the top. (Failed to initialize compiler: object java.lang.Object in compiler mirror not found ) So, if it is java8, there should be no problem, so install it.

`console`


$ brew cask install caskroom/versions/java8

Entered java8! So, switch immediately.

`console`


$ vi ~/.bashrc

`.bashrc`


export JAVA_HOME=`/System/Library/Frameworks/JavaVM.framework/Versions/A/Commands/java_home -v “1.8”`
PATH=$JAVA_HOME/bin:$PATH

`console`


$ source ~/.bashrc

$ activator run
...
...
(Server started, use Ctrl+D to stop and go back to the console...)

You did it. I had a great sense of accomplishment (I'm throwing something that seems to be the cause, but I was worried about 2 hours), but I came to write hello world, so I'll write it.

`routes`


GET			/hello									controllers.GreetController.index

`GreetController.scala`


package controllers

import javax.inject._
import play.api._
import play.api.mvc._

@Singleton
class GreetController @Inject() extends Controller {

  def index = Action {
    Ok("Hello world")
  }
}

Access [localhost: 9000 / hello](localhost: 9000 / hello).

Chissa www

environment

· Mac OS X EL Capitan 10.11.6 ・ Play 2.5.10

`console`


$ scala -version
Scala code runner version 2.12.5 -- Copyright 2002-2018, LAMP/EPFL and Lightbend, Inc.

$ java -version
java version "1.8.0_172"
Java(TM) SE Runtime Environment (build 1.8.0_172-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.172-b11, mixed mode)

reference

playframework Actions, Controllers and Results

Postscript [2018/09/12]

I added a title because it can not be used unless it is caught by the error content.

I got a good punch when trying Hello World in Scala (object java.lang.Object in compiler mirror not found.)

console

console

console

console

.bashrc

console

routes

GreetController.scala

environment

console

reference

Postscript [2018/09/12]

`console`

`console`

`console`

`console`

`.bashrc`

`console`

`routes`

`GreetController.scala`

`console`