Multiple Values per Key - PLEASE HELP!!

Question

hi. im trying to setup a TreeMap so it contains multiple values for each key using a List to store these values and a string as a key to reference them. however, although it compiles, i recieve a ClassCastException: java.util.ArrayList error when it runs. heres some of my code:
Map resultRelation = new TreeMap();
List list = new ArrayList();
list.add(value1);
list.add(value2);
resultRelation.put(Key, list);
i cant seem to find much useful information on this sort of thing. any help would be appreciated.

Answer 1

well after hours of labouring, it turns out that the code i posted is working but the problem is actually to do with printing out the values stored in the array. it was rather stupid of me but before i had created a print method which printed the key and its value from the map, assuming the value was one string not a List, and i hadn't updated it =) so the ClassCastException error was occuring because i was trying to cast the value (which is really a List) to a string in order to print it.
heres my updated printRelation method code as follows:
private static void printRelation(Map relation) {
Iterator keyIter = relation.keySet().iterator();
Iterator valueIter = relation.values().iterator();
while(keyIter.hasNext() == true) {
     String primaryKey = (String)keyIter.next();
     List foreignKey = (List)valueIter.next();
ConsoleIO.out.print(primaryKey); // ignore the ConsoleIO stuff. the key prints no prob.
Iterator iter = foreignKey.iterator();
while(iter.hasNext() == true) {
String value = (String)iter.next();
          ConsoleIO.out.print(value);
at the moment im only adding 1 value to the List as shown in my previous post. e.g.
list.add(foreignKey1);
all this works BUT im getting the wrong results. instead of printing out the key and only its values, its printing out the key and ALL the values from the text file im using. i think its either got something to do with my while loop or my casting of the List but this is all new ground for me =)
thanks.