Collection object which allows duplicate keys

Question

I wanted to know if there is any Collection object which allows me to store multiple values for a key.
I have the data:
key "a" - value "0"
key "a" - value "1"
key "a" - value "2"
key "b" - value "3"
key "b" - value "4"
key "c" - value "5"
Is there some collection object where I can store the above data which includes duplication of keys?

Answer 1

No. The values do not need to be stored twice. What I wanted to know
was if a key [say a in this case] can be repeated so as to store multiple
values [0, 1, 2] against it?Well, the solution is simple then: use a Set (no matter which one)
as the value part and collect all the (duplicate?) values in that set.
Something like this will do:public class Multi {
   private Map map= new HashMap();
   public void put(Object key, Object value) {
      Set values= (Set)map.get(key);
      if (values == null)
         map.put(key, values= new HashSet());
      values.put(value);
   public Set get(Object key) {
      return map.get(key);
}this was from the top of my head, typed in in a silly little reply box,
so no warranties apply etc. ;-)
kind regards,
Jos