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.
What does it mean exactly that you're "unable to edit the value of an existing key"?
Does it mean you don't know how to do it? Or does it mean you tried something, and it didn't work? And if it didn't work, then did you get a compiler error or a runtime error, or did the program behave differently from what you expected? Please explain in more detail.