NoClassDefFoundError calling Clojure from Java (Android, LibGDX)

Question

I've followed this tutorial to call Clojure from Java in Eclipse by using Leiningen. I want to code my game's AI in Clojure and do the rest in LibGDX for Android OS.

Once I have finished the Clojure side, I use the lein command to package it in a jar file (#lein compile, #lein run, #lein uberjar).

I add the jar file with right click on project > Properties > Java Build Path > Libraries > Add External JARs... > myai-0.1.0-SNAPSHOT-standalone.jar.

My problem occurs when I execute the game.

import myai.*;
public class Stack extends Actor {
   ...
   public void draw(SpriteBatch batch, float parentAlpha) {
      System.out.println("Binomial = " + core.binomial(5, 15));
   }
   ...
}

I receive this error:

12-26 00:27:01.570: I/dalvikvm(8384): Could not find method myai.core.binomial, referenced from method my.package.Stack.draw
12-26 00:27:01.570: E/AndroidRuntime(2281): FATAL EXCEPTION: GLThread
12-26 00:27:01.570: E/AndroidRuntime(2281): java.lang.NoClassDefFoundError: myai.core
12-26 00:27:01.570: E/AndroidRuntime(2281):     at my.package.Stack.draw(Stack.java:297)
12-26 00:27:01.570: E/AndroidRuntime(2281):     at my.package.GameScreen.render(GameScreen.java:146)
12-26 00:27:01.570: E/AndroidRuntime(2281):     at com.badlogic.gdx.Game.render(Game.java:46)
12-26 00:27:01.570: E/AndroidRuntime(2281):     at my.package.MyGame.render(MyGame.java:23)
12-26 00:27:01.570: E/AndroidRuntime(2281):     at com.badlogic.gdx.backends.android.AndroidGraphics.onDrawFrame(AndroidGraphics.java:487)
12-26 00:27:01.570: E/AndroidRuntime(2281):     at com.badlogic.gdx.backends.android.surfaceview.GLSurfaceViewCupcake$GLThread.guardedRun(GLSurfaceViewCupcake.java:713)
12-26 00:27:01.570: E/AndroidRuntime(2281):     at com.badlogic.gdx.backends.android.surfaceview.GLSurfaceViewCupcake$GLThread.run(GLSurfaceViewCupcake.java:646)

I really don't know why it happens because I have followed all steps in the tutorial.

These are my clojure files:

project.clj

(defproject myai "0.1.0-SNAPSHOT"
  :description "AI for my game"
  :url "http://example.com/FIXME"
  :license {:name "Eclipse Public License"
            :url "http://www.eclipse.org/legal/epl-v10.html"}
  :dependencies [[org.clojure/clojure "1.5.1"]]
  :aot [myai.core]
  :main myai.core)

core.clj

(ns myai.core
  (:gen-class
    :name myai.core
    :methods [#^{:static true} [binomial [int int] double]])
  )

(defn binomial
  "Calculate the binomial coefficient."
  [n k]
  (let [a (inc n)]
    (loop [b 1
           c 1]
      (if (> b k)
        c
        (recur (inc b) (* (/ (- a b) b) c))))))

(defn -binomial
  "A Java-callable wrapper around the 'binomial' function."
  [n k]
  (binomial n k))

(defn -main
  [& args]
  (println "My Game Artificial Intelligence")
  (println (str "(binomial 5 3): " (binomial 5 3)))
  )

Thanks in advance! :)

EDIT: It doesn't work either in Ubuntu with command line commands.

Answer 1

What a stupid mistake... I forgot to check the Clojure .jar file in Properties > Java Build Path > Order and Export tab, so it wasn't added to the classpath at compiling time.