java - Lambda reference to a field

Question

I'd like to know how to get lambda reference to a field. I don't want to use a method because my field is public final. I suspect this is impossible but I don't see an obvious statement.

class A {
   public final String id;
   ...
}

Map<String, A> f(List<A> l) {
   return l.stream().collect(Collectors.toMap(A::id, Function.identity()));
}

question from:https://stackoverflow.com/questions/27467946/lambda-reference-to-a-field

Answer 1

You can always use a lambda expression:

return l.stream().collect(Collectors.toMap(a -> a.id, Function.identity()));

I think that "method references" are called this way for a reason, and therefore apply only for methods.