5 public class Relation {
6 private Hashtable table;
10 table=new Hashtable();
18 public boolean containsKey(Object o) {
19 return table.containsKey(o);
23 return table.keySet();
26 public synchronized boolean put(Object key, Object value) {
28 if (table.containsKey(key)) {
29 s=(HashSet) table.get(key);
34 if (!s.contains(value)) {
42 public Set get(Object key) {
43 return (Set)table.get(key);