Trick the eye

Posted Mon, 22/06/2009 - 21:53 by shlomo
, , ,

I admit I was tricked:

 

import java.util.ArrayList;
public class ListProvider {
  public static <ArrayList> ArrayList getList(ArrayList ar) {
    return ar;
  }
  public static void main(String[] args) {
      getList("I am a list");
  }
}

This code compiles and runs of course.

Comments

by yanai - 22/06/2009 - 22:39

IMO, rule no.1 in generics : "Don't redefine a class using a Type unless you deliberately want to confuse people."

BTW - The compiler will give you a warning about it : "The type parameter ArrayList is hiding the type ArrayList". so rule no.2 - don't ignore compiler warnings...