Calling clojure from java

Question

Most of the top google hits for \"calling clojure from java\" are outdated and recommend using clojure.lang.RT to compile the source code. Could you help with a

Answer 1

I agree with clartaq's answer, but I felt that beginners could also use:

• step-by-step information on how to actually get this running
• information that's current for Clojure 1.3 and recent versions of leiningen.
• a Clojure jar that also includes a main function, so it can be run standalone or linked as a library.

So I covered all that in this blog post.

The Clojure code looks like this:

(ns ThingOne.core
 (:gen-class
    :methods [#^{:static true} [foo [int] void]]))

(defn -foo [i] (println "Hello from Clojure. My input was " i))

(defn -main [] (println "Hello from Clojure -main." ))

The leiningen 1.7.1 project setup looks like this:

(defproject ThingOne "1.0.0-SNAPSHOT"
  :description "Hello, Clojure"
  :dependencies [[org.clojure/clojure "1.3.0"]]
  :aot [ThingOne.core]
  :main ThingOne.core)

The Java code looks like this:

import ThingOne.*;

class HelloJava {
    public static void main(String[] args) {
        System.out.println("Hello from Java!");
        core.foo (12345);
    }
}

Or you can also get all the code from this project on github.