Exposing your code to Java

If you want to be able to use Clojure code from other JVM languages, in Clojure, there are a couple of ways in which you can do it:

• You can generate new Java classes and use them as you normally would; it can implement some interface or extend from some other class

• You can generate a proxy on the fly, this way you can implement a contract (in the form of a class or an interface) that some framework requires with little code and effort

• You can use the clojure.java.api package to call Clojure functions directly from Java

Note

You can find more information on how this works at the following location: http://www.falkoriemenschneider.de/a__2014-03-22__Add-Awesomeness-to-your-Legacy-Java.html.

Let's have a look at how we can define a Java class.

Create a new namespace called thumbnails.image-java and write the following code:

(ns thumbnails.image-java
  (:require [thumbnails.image :as img])
  (:gen-class
    :methods [[loadImage [java.io.InputStream] java.awt.image.BufferedImage...