Base.java: public abstract class Base extends Base2 { } Base2.java: public class Base2 { public void print(Object out) { System.out.println("Base:"+out); } } Simple.groovy class Simple extends Base { static void main(args) { simple = new Simple() simple.process() } void process() { print("ok") } } prints out "ok" instead of "Base:ok" Trying with Simple.java: public class Simple extends Base { public static void main(String[] args) { Simple simple = new Simple(); simple.process(); } public void process() { print("ok"); } } behaves correctly