[Aaron Zapashniy]

Hi. i'm starting to add generics to a lot of my 1.4 code. i have a utility method which takes in a container of SuperClass. i'm now getting compile errors when i pass it a container of Subclass. why?

[Starwarrior]

Because a container of a superclass is not a superclass of a container of a subclass.

[Aaron Zapashniy]

I.e. void doIt(List<Parent>){ ...} ... List<Child> list = new List<Child>(); doIt(list);
That's not legal?

[Ikopar]

No

[Poolkop]

Aaron Zapashniy, generics is http://java.sun.com/j2se/1.5.0/docs/guide/language/generics.html and the generics tutorial is http://java.sun.com/j2se/1.5/pdf/generics-tutorial.pdf and http://www.angelikalanger.com/GenericsFAQ/JavaGenericsFAQ.html

[Aaron Zapashniy]

Hm. odd. how useful are these things then?

[amoralis]

How about List<Parent> list = new List<Child>(); doIt(list); ?
Is that still invalid?

[Ikopar]

Yep

[amoralis]

<- doesn't get to use generics

[Ikopar]

It's unnecessary too