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.
An array would need to have a dimension specified, so I dont think you can create an infinite 2D array. You can search on this forum for more queries related to Two dimensional arrays.
But if you are looking for some structure whose size would increase dynamically- you can consider a ArrayList.