Importing .jar files into Scala environment

Question

Even after reading: Scala, problem with a jar file, I'm still a bit confused. I am trying to import some packages into my Scala file, and the interpreter is not recognizing them even after adding to classpath.

One example:

I have the import statement:

import org.json4s._

I downloaded the .jar from here: http://mvnrepository.com/artifact/org.json4s/json4s-native_2.10/3.2.4

and added to the interpreter classpath using:

scala> :cp /Users/aspangher13/Downloads/json4s-native_2.10-3.2.4.jar

Scala acknowledges the classpath:

Your new classpath is: ".:/Users/aspangher13/Downloads/json4s-native_2.10-3.2.4.jar:/Users/aspangher13/Downloads/jna-3.5.2.jar"

But still throws this error:

<console>:7: error: object scalatra is not a member of package org
   import org.json4s._

Can anyone see what I'm doing wrong? Thanks!!

And as a followup, does anyone know where to find the package: JsonAST._?

Why not to go simple way, use sbt, drop libraries into ./lib/ folder and call `console`? — 4lex1v, Jul 02 '13 at 16:30
Alexlv is right, of course. But I think the problem you have is that you've only included JSON4S support, not all of Scalatra (or even its core). — Randall Schulz, Jul 02 '13 at 16:33
Sorry, to clarify, I just included that as an example of an import statement that wasn't working — Alex Spangher, Jul 02 '13 at 18:58

score 6 · Accepted Answer · answered Jul 02 '13 at 17:01

Go the simple and create a little sbt project.

First step - create a project

For your purposes you don't need a complex build. So just create two files:

./build.sbt

name := "name your project"

version := "0.1"

scalaVersion := "2.10.2" // or whatever you prefer

./project/build.properties

sbt.version=0.12.4

The just go to the project root folder and call sbt

Second step - add dependencies

Open your ./build.sbt file and add:

libraryDependency ++= Seq(
  "org.scalatra" %% "scalatra" % "2.2.1",
  "org.scalatra" %% "scalatra-scalate" % "2.2.1",
  "org.scalatra" %% "scalatra-specs2" % "2.2.1" % "test",
  "org.json4s"   %% "json4s-native % "3.2.4",
  "net.java.dev.jna" & "jna" & "3.5.2"
)

Step three - run the console

Don't forget to reload sbt with reload task, and then call console or console-quick task. This should work.

But there are easier ways to do this:

1) Use gitter8 - Scalatra gitter8 project
2) Read little into about Scalatra sbt dependencies

-1 Next time answer the question. SBT is not a part of Scala. — Rok Kralj, Jul 15 '14 at 18:44
I agree, Sbt is not the answer, :cp behavior is confusing me too, please explain how it works in the REPL — pferrel, Dec 25 '14 at 18:05
@pferrel Well, i think that it was the answer for the topicstarter. I know how to solve problem using SBT, if you don't know this tool or don't know how to use it, you can always open a question and ask whatever you'd like to know. — 4lex1v, Dec 29 '14 at 05:38

pferrel · Answer 2 · 2014-12-25T18:24:38.020

Still not sure how :cp works but if you execute

scala -classpath "list of jars colon separated"

then inside the REPL do your imports it should work

import org.json4s._
import org.xyz

However, when you try to use the classes you are likely to be missing transitive dependencies required by json4s and so we come back to the sbt example @ 4lex1v describes, which will handle this. Creating a little project and running sbt console will indeed greatly simplify this.

Seems like the -classpath and :cp are primarily meant to make your code available in the shell and then only if you understand all of the transitive dependencies, or have none.

Importing .jar files into Scala environment

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