Re: abstract classes and generic types

From:

horos11@gmail.com

Newsgroups:

comp.lang.java.programmer

Date:

Sun, 17 May 2009 17:00:13 -0700 (PDT)

Message-ID:

<842f1a0c-bb2f-4d60-800f-03be3ed4c186@w35g2000prg.googlegroups.com>

BTW - with the below I did find a workaround. If I say:

     private<K> void _setHelper(Set<K> parm, Integer key)
     {
         parm.add((K) key);
     }

ie, ie explicitly cast it, this works. But it also tells me that I'm
using unsafe operations.
This should not be unsafe - there's got to be a better solution than
this out there. Else are generics inherently unsafe?

import java.util.*;
class AA
{

    Set<?> example;

    aa()
    {
         example = new HashSet<Integer>();
        _setHelper(example, new Integer(1));
         System.out.println(example);
    }

    private<K> void _setHelper(Set<K> parm, K key)
    {
        parm.add(key);
    }

}

where I'm attempting to give the compiler a little push in the right
direction, showing that Set<K> should be linked with the ?. I would
have thought this would have worked, but no.

Of course, if I explicitly cast it - (Set<Integer>)example, it works,
but that gets rid of the point of generics, doesn't it?

So any ideas around this?

(ps - wrt language lawyering, with all respect I detest camelcase, and
will only use it if required by convention. And no - I don't go around
naming my variables mySet, etc.. I do it for example.. so thanks for
the concern, but no thanks..