ProxyTest.java

import java.lang.reflect.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;

public class ProxyTest {

    private static interface CatInterface {
        public CatInterface printName();
        public CatInterface sayMeow();
    }

    private static class Cat implements CatInterface {
        public final String name;

        private Cat(String name) {
            this.name = name;
        }

        public Cat printName() {
            System.out.println(name);
            return this;
        }

        public Cat sayMeow() {
            System.out.println(name + " says 'meow!'");
            return this;
        }
    }

    public static void main(String[] args) {
        List<CatInterface> cats = Arrays.<CatInterface>asList(new Cat("Felix"), new Cat("Tiger"), new Cat("Tom"));
        forEach(CatInterface.class, cats).printName().sayMeow();
    }

    @SuppressWarnings("unchecked")
    public static <T> T forEach(Class<T> clazz, Collection<T> collection) {
        T proxy = (T) Proxy.newProxyInstance(
                ForEachInvocationHandler.class.getClassLoader(),
                new Class[] { clazz },
                new ForEachInvocationHandler<T>(clazz, collection)
        );
        return proxy;
    }

    private static class ForEachInvocationHandler<T> implements InvocationHandler {
        private final Collection<T> collection;
        private final Class<T> clazz;

        private ForEachInvocationHandler(Class<T> clazz, Collection<T> collection) {
            this.collection = collection;
            this.clazz = clazz;
        }

        @Override
        @SuppressWarnings("all")
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            List result = new ArrayList();

            for (T elem : collection) {
                result.add(method.invoke(elem, args));
            }

            return forEach(clazz, result);
        }
    }

}