The intention behind using generics is to avoid surprises for the JVM.
i.e., You should use generics to avoid runtime(class cast) exceptions.
So in this case you are ought to get this warning in eclipse. There is
nothing wrong in type casting as well, as you are sure that the
attribute you are getting is what you have set before. Well, you can
avoid this warning by implementing Map interface and having  something
like this:-

class ItemInfoMap extends HashMap<String,ItemInfo> implements
Map<String,ItemInfo>{
public ItemInfoMap put(String key, ItemInfo value) {
   return super.put(key, value);
}
public ItemInfoMap get(String key) {
   return super.get(key, value);
}

}

Now Use ItemInfoMap instead of Map :-)

ItemInfoMap userCart = (ItemInfoMap)
session.getAttribute("userCart");

Hope this helps!

Thanks!

What happens when you cast it to a generic like this:

Ultimately, generics are erased, and this compiles down to

Hashtable userCart = (Hashtable) session.getAttribute("userCart");

You get the warning, since the runtime will only cast your  
"session.getAttribute" to Hashtable, and can not verify the contents of  
the table. Thus, a subsequent call to

ItemInfo info=userCart.getValue("somevalue");

*could* spuriously throw a ClassCastException (since the cast to ItemInfo  
is automatically generated by the compiler).

Some other posters have commented on using a Map instead of Hashtable. It  
would be a good idea, when map is initially created, to use  
Collections.checkedMap - which will ensure that the contents are what you  
expect.

Map<String, ItemInfo> cart=Collections.checkedMap(
    Collections.synchronizedMap(new HashMap()),
    String.class,
    ItemInfo.class));

Now, you can safely assume that the contents of your map are always  
String, ItemInfo. The compiler will still generate the same warning, which  
you can now safely turn off by decorating the calling method with

@SuppressWarnings("unchecked")

Note that this turns off all unchecked cast warnings in that method, so do  
make sure that you have taken reasonable precautions to externally protect  
your data before turning off the warning.

HTH,

-Zig