This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
You never initialize dotComsList. The NullPointerException tells you exactly on which line it occurs (DotComBust.java, line 19). Then you look on that line for any dereferencing. In this case, the line is dotComsList.add(one); and only dotComsList is dereferenced. Therefore it must be null.