Not sure what you are expecting this tool to do but I would create some data structures to record these times and counts like
class UserActionStats {
int count;
long durationMS;
long start = 0;
public void startAction() {
start = System.currentTimeMillis();
}
public void endAction() {
durationMS += System.currentTimeMillis() - start;
count++;
}
}
A collection for these could look like
private static final Map<String, UserActionStats> map =
new HashMap<String, UserActionStats>();
public static UserActionStats forUser(String userName) {
synchronized(map) {
UserActionStats uas = map.get(userName);
if (uas == null)
map.put(userName, uas = new UserActionStats());
return uas;
}
}