access clojure via java classes

Question

Hello I have a main method in a Java class and I would like to access and run my clojure functions from my java classes, is that possible right?

Help please

I think you're mis-spelling something 'clojure'. Don't get it though, I say 'Yes'. — Pete Houston, Oct 05 '11 at 13:06

score 4 · Accepted Answer · answered Oct 05 '11 at 13:13

4

If you just want to call a function which you have defined in a Clojure script the following code might help you getting the job done:

test.clj:

(ns test)
(defn hello [name]
  (println (str "Hi " name "!")))

TestRun.java:

import clojure.lang.RT;
public class TestRun {
    public static void main(String[] args) throws Exception {
        RT.loadResourceScript("test.clj");
        // var(namespace, function name).invoke(parameters..)
        RT.var("test", "hello").invoke("Daisy Duck");
    }
}

Output:

Hi Daisy Duck!

Make sure you have the Clojure jar on your classpath

answered Oct 05 '11 at 13:13

Matt

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In 2008 before clojure had ahead of time compilation this was the answer. It is terribly innefficient today. the correct answer is to compile a class with methods and call them from java as you would anything else. no need to compile at every run – Arthur Ulfeldt Oct 05 '11 at 18:08
Yep, you're certainly right. I prefer to optimize when speed becomes an issue ;) – Matt Oct 05 '11 at 22:58

score 2 · Answer 2 · answered Oct 05 '11 at 13:07

2

Do you have your Clojure code compiled and packaged in a jar? Do you have the jar in your classpath? If so, you should be able to use the classes in the jar just as if there were written in Java.

answered Oct 05 '11 at 13:07

John B

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score 2 · Answer 3 · edited May 23 '17 at 12:27

see the accepted answer to this question: Calling clojure from java

in short you add the mothods you want to expose to your namespace:

(ns com.domain.tiny
  (:gen-class
    :name com.domain.tiny
    :methods [ [binomial [int int] double]]))

then write the functions. compile your class file with maven/leiningen

then call them from java:

System.out.println("(binomial 5 3): " + tiny.binomial(5, 3));

This is just an excerpt. take a look as the origional question.

score 0 · Answer 4 · answered Oct 05 '11 at 13:12

0

Check the Java Scripting API for calling functions in script files: http://download.oracle.com/javase/6/docs/technotes/guides/scripting/programmer_guide/index.html

answered Oct 05 '11 at 13:12

Angel O'Sphere

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access clojure via java classes

4 Answers4