Hashtable<Object, Integer> hash= new Hashtable<Object, Integer>();

Map<Object, Integer> hash= new Hashtable<Object, Integer>();
SortedSetMultimap<Integer, Object> reverse = TreeMultimap.create();

public static void main(String[] args) {


    HashMap<String,Integer> map = new HashMap<String,Integer>();

    map.put("A", 1);
    map.put("B", 2);
    map.put("C", 3);

    System.out.println(

    Collections.min(map.entrySet(), new Comparator<Map.Entry<String,Integer>>() {

        @Override
        public int compare(Entry<String, Integer> o1, Entry<String, Integer> o2) {

            return o1.getValue().intValue() - o2.getValue().intValue();

        }})

        .getKey()


    );
}

Object minObj= null;
int min= Integer.MAX_VALUE;
for(Map.Entry<Object, Integer> x: hash.entrySet()){
    if(x.getValue() < min){
            min= x.getValue();
            minObj= x.getKey();
    }
}

Hashtable h = new Hashtable();
    h.put(10, "aaa");
    h.put(1, "aab");
    h.put(12, "aabwqkjdg");

    Set set = h.keySet();

    TreeSet treeSet= new TreeSet();
    treeSet.addAll(set);

    System.out.println("Last :"+treeSet.first());