If you want to keep the keys sorted use a treemap like this:
TreeMap<Integer, Integer> map = new TreeMap<>();
map.put(100, 200);
map.put(150, 300);
map.put(1, 200);
map.put(-100, 800);
map.put(-50, 8000);
map.put(900, 2000);
map.put(700, 6000);
log("Smallest key: " + map.firstKey() + " -> " + map.get(map.firstKey()));
log("Largest key: " + map.lastKey() + " -> " + map.get(map.lastKey()));
log("Iterating keys:");
for(int k : map.descendingKeySet()) {
log(k);
}