Creating an instance of the Java Scripting Engine class

Question

Creating an instance of the Java Scripting Engine class

Currently, I am facing a challenge while trying to integrate a scripting endpoint into our application. The issue at hand is as follows: Is it viable to create an object that is an instance of an abstract class with implemented methods? In the context of Java, the scenario would resemble the following:

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

In this case, SimpleObject is an abstract class containing an abstract method called doCustomAction. How can one achieve such behavior using a Java Scripting Engine? My attempt involves the following approach:

obj1 = new SimpleObject("value1") {
    doCustomAction : function() {
       //Perform actions.
    }
}

Unfortunately, an exception is thrown by the engine:

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

java javascript scripting

Answer 1

Answer №1

To enhance your abstract class in Java, you can create a similar setup to how MouseAdapter utilizes interfaces. Then, in JavaScript, you can utilize this "adapter" concept in the following way:

In Java:

public abstract class CustomObject {
   abstract void performCustomAction();
}
public class CustomObjectAdapter extends CustomObject {
   void performCustomAction(){}
}

In JavaScript:

obj1 = new JavaAdapter(CustomObjectAdapter,{
    performCustomAction : function() {
       //Implement custom action.
    }
});

Alternatively, without using the "adapter", you can simply do:

obj1 = new JavaAdapter(Packages.CustomObject, {
   performCustomAction: function(){
      //Implement custom action.
   }
});

Answer 2

To enhance your abstract class in Java, you can create a similar setup to how MouseAdapter utilizes interfaces. Then, in JavaScript, you can utilize this "adapter" concept in the following way:

In Java:

public abstract class CustomObject {
   abstract void performCustomAction();
}
public class CustomObjectAdapter extends CustomObject {
   void performCustomAction(){}
}

In JavaScript:

obj1 = new JavaAdapter(CustomObjectAdapter,{
    performCustomAction : function() {
       //Implement custom action.
    }
});

Alternatively, without using the "adapter", you can simply do:

obj1 = new JavaAdapter(Packages.CustomObject, {
   performCustomAction: function(){
      //Implement custom action.
   }
});

Creating an instance of the Java Scripting Engine class

Answer №1

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