Using Map

    Map map = new HashMap(); // instantiate a concrete map
    ...
    map.put(key, val); // insert a key-value pair
    ...
    // get the value associated with key
    Object val = map.get(key);
    map.remove(key); // remove a key-value pair
    if (map.containsValue(val)) { ... }
    if (map.containsKey(key)) { ... }
    Set keys = map.keySet(); // get the set of keys
    // iterate through the set of keys
    Iterator iter = keys.iterator();
    while (iter.hasNext()) {
        Object key = iter.next();
        Object val = map.get(key);
        ...
    }