Java Scripting Engine class instantiation

Question

I'm trying to implement scripting endpoint in our application, but I have a problem: Is it possible to instantiate an object that is instance of abstract class with implemented methods? In Java it will look like:

SimpleObject obj = new SimpleObject("contructor arg0") {    
   public void doCustomAction() {
     System.out.println("Action");
   }
}

SimpleObject is an abstract class with abstract method doCustomAction How to do such thing via Java Scripting Engine? I'm trying to do in the following way:

obj1 = new SimpleObject("value1") {
    doCustomAction : function() {
       //Do smth.
    }
}

But engine throws such exception:

javax.script.ScriptException: sun.org.mozilla.javascript.internal.EvaluatorException:
   error instantiating (JavaAdapter: first arg should be interface Class (<Unknown source>#1)): 
  class SimpleObject is interface or abstract (<Unknown source>#1) in <Unknown source> at line number 1

Prusse · Accepted Answer · 2011-10-19 17:19:43Z

2

You could extend your abstract class in Java, something like MouseAdapter does with its interfaces, then in javascript you use this "adapter", like:

In Java:

public abstract class SimpleObject {
   abstract void doCustomAction();
}
public class SimpleObjectAdapter extends SimpleObject {
   void doCustomAction(){}
}

In JavaScript:

obj1 = new JavaAdapter(SimpleObjectAdapter,{
    doCustomAction : function() {
       //Do smth.
    }
});

Edit: You could do it without the "adapter", just do:

obj1 = new JavaAdapter(Packages.SimpleObject, {
   doCustomAction: function(){
      //Do smth.
   }
});

edited Oct 19, 2011 at 17:19

answered Oct 19, 2011 at 16:47

Prusse

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