This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
Some possible improvements: 1) you're storing Integers in your List. You know this. Yet when you retrieve them, you convert them to string, then retrieve the int value from them. Something you already have:
2) store the result of System.currentTimeMillis() in your list. No need to create a Date object, format it, then call toString on a String (?) and then parse that as seconds. System.currentTimeMillis() already returns the current moment in time, with an accuracy of 10-20ms mostly: