Map that allows duplicate keys

Question

Is there a map that allows duplicate keys? The get(Object key) method will then return a Collection.

Answer 1

Thanks, I made my own class with some help from previous threads.
    private class DuplicateMap {
        private Map map = new HashMap();
        public void put(Object key, Object value) {
            List existing = (List)map.get(key);
            if (existing == null) {
                List list = new ArrayList();
                list.add(value);
                map.put(key, list);
            } else {
                existing.add(value);
        public List get(Object key) {
            List returnValue = (List)map.get(key);
            if (returnValue == null) {
                returnValue = new ArrayList();
            return returnValue;
    }