1) String action; //the name of the action itself
2) String categoryOfAction; //the category of the action
3) Integer personWhoPerformedAction; //the person that did the action
4) Long timeOfOccurrence; //the time the action was done

String[] actionOccurances = map1.get(action); //returns every occurrence of that action (possibly in an array), including who did that occurrence, time the occurrence occurred, and the category of that occurrence

Long latestOccurance = map2.get(action); //returns the latest occurrence of that action

String[] actionsPerformedByPerson = map3.get(personWhoPerformedAction); //returns every action that this person has done, including the category of that action, the time they performed that action, and the name of the action itself

DB thedb = DBMaker.newTempFileDB().make();

NavigableSet<Object> map1 = thedb.createTreeSet("actionOccurences").comparator(Fun.COMPARABLE_ARRAY_COMPARATOR).make();

HTreeMap<String, Long> map2 = thedb.getHashMap("lastOccurrence");

NavigableSet<Object> map3 = thedb.createTreeSet("actionsPerformedByPerson").comparator(Fun.COMPARABLE_ARRAY_COMPARATOR).make();