Classpath Bug -

[Nikolay Botev]

Nikolays-MacBook-Air:bin nbotev$ uname -a
Darwin Nikolays-MacBook-Air.local 14.4.0 Darwin Kernel Version 14.4.0: Thu May 28 11:35:04 PDT 2015; root:xnu-2782.30.5~1/RELEASE_X86_64 x86_64

Nikolays-MacBook-Air:bin nbotev$ java -version
java version "1.9.0-ea"
Java(TM) SE Runtime Environment (build 1.9.0-ea-b72)
Java HotSpot(TM) 64-Bit Server VM (build 1.9.0-ea-b72, mixed mode)

JShell verison: kulla-0.610-20150709005843

——

Summary: Adding a library to the class path after loading a class that depends on that library does not reload the class.

Reproduction Steps:

- Download akka from http://downloads.typesafe.com/akka/akka_2.11-2.3.12.zip?_ga=1.210377941.1593193379.1436640268

- Run in jshell:

Nikolays-MacBook-Air:bin nbotev$ jshell 
|  Welcome to JShell -- Version 0.610
|  Type /help for help

-> /classpath ~/Downloads/akka-2.3.12/lib/scala-library-2.11.5.jar
|  Path ~/Downloads/akka-2.3.12/lib/scala-library-2.11.5.jar added to classpath

-> /classpath ~/Downloads/akka-2.3.12/lib/akka/akka-actor_2.11-2.3.12.jar
|  Path ~/Downloads/akka-2.3.12/lib/akka/akka-actor_2.11-2.3.12.jar added to classpath

-> akka.actor.ActorSystem system = akka.actor.ActorSystem.create("MySystem")
|  java.lang.NoClassDefFoundError thrown: com/typesafe/config/ConfigFactory
|        at ActorSystem$$anonfun$5.apply (ActorSystem.scala:141)
|        at ActorSystem$$anonfun$5.apply (ActorSystem.scala:141)
|        at Option.getOrElse (Option.scala:121)
|        at ActorSystem$.apply (ActorSystem.scala:141)
|        at ActorSystem$.apply (ActorSystem.scala:109)
|        at ActorSystem$.create (ActorSystem.scala:57)
|        at ActorSystem.create (ActorSystem.scala)
|        at (#9:1)

-> /classpath ~/Downloads/akka-2.3.12/lib/akka/config-1.2.1.jar
|  Path ~/Downloads/akka-2.3.12/lib/akka/config-1.2.1.jar added to classpath

-> akka.actor.ActorSystem system = akka.actor.ActorSystem.create("MySystem")
|  java.lang.NoClassDefFoundError thrown: com/typesafe/config/ConfigFactory
|        at ActorSystem$$anonfun$5.apply (ActorSystem.scala:141)
|        at ActorSystem$$anonfun$5.apply (ActorSystem.scala:141)
|        at Option.getOrElse (Option.scala:121)
|        at ActorSystem$.apply (ActorSystem.scala:141)
|        at ActorSystem$.apply (ActorSystem.scala:109)
|        at ActorSystem$.create (ActorSystem.scala:57)
|        at ActorSystem.create (ActorSystem.scala)
|        at (#9:1)

-> /classpath ~/Downloads/akka-2.3.12/lib/akka/akka-actor_2.11-2.3.12.jar
|  Path ~/Downloads/akka-2.3.12/lib/akka/akka-actor_2.11-2.3.12.jar added to classpath

-> akka.actor.ActorSystem system = akka.actor.ActorSystem.create("MySystem")
|  java.lang.NoClassDefFoundError thrown: com/typesafe/config/ConfigFactory
|        at ActorSystem$$anonfun$5.apply (ActorSystem.scala:141)
|        at ActorSystem$$anonfun$5.apply (ActorSystem.scala:141)
|        at Option.getOrElse (Option.scala:121)
|        at ActorSystem$.apply (ActorSystem.scala:141)
|        at ActorSystem$.apply (ActorSystem.scala:109)
|        at ActorSystem$.create (ActorSystem.scala:57)
|        at ActorSystem.create (ActorSystem.scala)
|        at (#9:1)

Workaround:

Load the JAR *before* referencing the class that depends on classes in the JAR, as below:

Nikolays-MacBook-Air:bin nbotev$ jshell 
|  Welcome to JShell -- Version 0.610
|  Type /help for help

-> /classpath ~/Downloads/akka-2.3.12/lib/scala-library-2.11.5.jar
|  Path ~/Downloads/akka-2.3.12/lib/scala-library-2.11.5.jar added to classpath

-> /classpath ~/Downloads/akka-2.3.12/lib/akka/akka-actor_2.11-2.3.12.jar
|  Path ~/Downloads/akka-2.3.12/lib/akka/akka-actor_2.11-2.3.12.jar added to classpath

-> /classpath ~/Downloads/akka-2.3.12/lib/akka/config-1.2.1.jar
|  Path ~/Downloads/akka-2.3.12/lib/akka/config-1.2.1.jar added to classpath

-> akka.actor.ActorSystem system = akka.actor.ActorSystem.create("MySystem")
|  com.typesafe.config.ConfigException$Missing thrown: No configuration setting found for key 'akka'
|        at SimpleConfig.findKey (SimpleConfig.java:124)
|        at SimpleConfig.find (SimpleConfig.java:147)
|        at SimpleConfig.find (SimpleConfig.java:159)
|        at SimpleConfig.find (SimpleConfig.java:164)
|        at SimpleConfig.getString (SimpleConfig.java:206)
|        at ActorSystem$Settings.<init> (ActorSystem.scala:169)
|        at ActorSystemImpl.<init> (ActorSystem.scala:505)
|        at ActorSystem$.apply (ActorSystem.scala:142)
|        at ActorSystem$.apply (ActorSystem.scala:109)
|        at ActorSystem$.create (ActorSystem.scala:57)
|        at ActorSystem.create (ActorSystem.scala)
|        at (#9:1)