How to select a random key from a HashMap in Java?

Question

I\'m working with a large ArrayList>, and I would repeatedly need to select a random key from a random HashMap (and do some stuff with it).

Answer 1

from top of my head

List keysAsArray = new ArrayList(map.keySet())
Random r = new Random()

then just

map.get(keysAsArray.get(r.nextInt(keysAsArray.size()))