void (Consumer<? super K> action) { if (action == null) throw new NullPointerException(); Node<K,V>[] t; if ((t = map.table) != null) { Traverser<K,V> it = new Traverser<K,V>(t, t.length, 0, t.length); for (Node<K,V> p; (p = it.advance()) != null; ) action.accept(p.key); } }