This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
First of all this is in the wrong forum! This forum is for JSP related stuff and your question has more to do with core java.
Now to your question. I think what you meant was how to make operations on an ArrayList synchronized. The ArrayList methods as such are not synchronized. You can either write a wrapper class and synchronize the calls, or you can use the Vector class which has the same functionality as that of ArrayList, but its methods are synchronized