Clojure : call a java subclass of abstract class

Question

I have a problem today because I do not know how to call a java class which extends a sublass. I know there is the $ sign for nested class but here I'm lost.

To be more clear, here are the classes :

Abstract class :

http://commons.apache.org/proper/commons-math/apidocs/org/apache/commons/math3/fitting/AbstractCurveFitter.html

Subclass :

http://commons.apache.org/proper/commons-math/apidocs/org/apache/commons/math3/fitting/SimpleCurveFitter.html

To be honest, I forgot a lot of thing about java but I see there is no constructor for the subclass. The problem is that I must use the sublass.

Here is the code

(defn apache-logistic-reg [data x0 lamb] (let [f (Logistic$Parametric.) start (def-start x0 lamb) fitter (.create SimpleCurveFitter. f start) points (double-array (extract-points data))] (.fit fitter points)))

The problem is that I cannot call SimpleCurveFitter. because it has no constructor. And AbstractCurveFitter has no .create, plus if I remember it well abstract classes cannot be cast.

And if I remember well, the constructor of SimpleCurveFitter would have the name of its abstract class but maybe I'm wrong.

How can I do ?

Thanks you

resueman · Accepted Answer · 2016-02-23 21:41:17Z

You don't need to call a constructor in SimpleCurveFitter, because it provides the static method create to get an instance for you (which you're already trying to use). Just make a static method call to that method to get an instance:

(.create SimpleCurveFitter f start) ;; No '.' after SimpleCurveFitter (. SimpleCurveFitter create f start) ;; Alternate syntax (SimpleCurveFitter/create f start) ;; Most common syntax (pointed out by amalloy)

Thanks a lot, finally it was "simple" like String and so on, I imagined harder manipulations !
The third syntax here is by far the most typical one to use for calling static methods.

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