I have a problem with bounded nested wildcards in Java generics.
Here's a common case:
public void doSomething(Set<? extends Number> set) {} public void callDoSomething() { Set<Integer> set = new HashSet<Integer>(); doSomething(set); }
This is standard Java generics, works fine.
However if the wildcard becomes nested, it no longer works:
public void doSomething(Map<String, Set<? extends Number>> map) {} public void callDoSomething() { Map<String, Set<Integer>> map = new HashMap<String, Set<Integer>>(); doSomething(map); }
This leads to a compiler error.
I've tried a variety of casts and wildcard permutations, but I'm unable to get this working. I don't recall seeing this issue before, and I've worked with generics for years. Am I just too tired and missing something obvious?