Cannot instantiate the type Set

Question

I am trying to create a Set of Strings which is filled with the keys from a Hashtable so a for-each loop can iterate through the Set and put defaults in a Hashtable. I am st

Answer 1

HashMap's keySet() method already creates the set you need, so simply:

Set keys = defaults.keySet();

This is a view of the keys in defaults, so its contents will change when changes are made to the underlying (defaults) map. Changes made to keys will be reflected in the map, as well, but you can only remove...not add...keys from the map.

If you need a copy of the keys that doesn't interact with the original map, then use one of the types suggested, as in:

Set keys = new HashSet( defaults.keySet() );