Java syntax like "DefaultEdge.class" is (more or less) just syntactic sugar for
'java.lang.Class.forName("org.jgrapht.graph.DefaultEdge");' which in Jess will
come out like "(Class.forName org.jgrapht.graph.DefaultEdge)" (taking
advantage of the default static imports from the java.lang package.) So you
want to do something like
(bind ?edge-class (Class.forName org.jgrapht.graph.DefaultEdge))
(bind ?graph (new org.jgrapht.graph.DefaultDirectedGraph ?edge-class))
From: owner-jess-us...@sandia.gov [mailto:owner-jess-us...@sandia.gov] On
Behalf Of Aurélien Mazurie
Sent: Wednesday, August 07, 2013 7:11 PM
To: jess-users
Subject: JESS: [EXTERNAL] Issue with static methods (or generics?)
Dear Jess users,
I am having trouble instantiating a Java class from within a rule's RHS, and
cannot figure out how to solve this problem.
The code in my RHS creates an instance of a class from the JGraphT library. As
seen in
https://github.com/jgrapht/jgrapht/blob/master/jgrapht-demo/src/main/java/org/jgrapht/demo/HelloJGraphT.java
(lines 91-92), the creation of a DefaultDirectedGraph instance require another
class as argument; here, DefaultEdge.
I couldn't find an example in the Jess documentation about how to do that. For
example, I tried the following:
(bind ?edge-class org.jgrapht.graph.DefaultEdge)
(bind ?graph (new org.jgrapht.graph.DefaultDirectedGraph
?edge-class))
I also tried variations such as
(bind ?edge-class org.jgrapht.graph.DefaultEdge)
(bind ?graph (new org.jgrapht.graph.DefaultDirectedGraph
(?edge-class getClass))
or
(bind ?edge-class (new org.jgrapht.graph.DefaultEdge))
(bind ?graph (new org.jgrapht.graph.DefaultDirectedGraph
?edge-class))
Any idea about what the syntax should be to properly instantiate the
DefaultDirectedGraph class? For information (but not certain how relevant it is
here), I succeeded in the past in using java.util.regex.Pattern and its static
method 'compile' by typing
(bind ?pattern-class java.util.regex.Pattern)
(bind ?matches ((?pattern-class compile "...") matcher ?string))
Best,
Aurélien
