Question

I have an abstract class which is mostly instantiated as anonymous inner classes, with abstract method implemented there. These instances get passed around, and so at a different place in the code I would like to get a copy of one of these instances, a new instance but with the method implemented the same way. Here is an example of my code:

public abstract class AbstractClass {
String id;
Entity owner;
public AbstractClass(String id){
    this.id=id;
} 
public Mover(){
    id="This is an id";
}
abstract void update();
}

I instantiate it like this:

AbstractClass instance= new AbstractClass("This is a test"){
void update(){
//do stuff
}
}

Later, I want a copy, not a reference, of that instance, where update() does the same stuff, but owner will be a different entity. I’ve tried to use reflection, (.getClass.newInstance()), but I get a java.lang.InstantiationException. Why doesn’t this work and is there a better way to do what I’m doing?

Answer 1

You can’t instantiate anonymous inner classes through newInstance(). Non-static inner classes hold a reference to their container Object, you need that Object to create them.

See Java Tutorial -> Nested Classes