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.
It looks to me like you have not made provision for writing out the modified XML document. You have modified the DOM in memory but that will not change the disk file automatically. The tools used to write a DOM depend on the Java version and/or outside toolkit you are using. IF you have Java 1.4 or 1.5 - look at the javax.xml.transform package. Any XML tutorial will have example code. Bill