can XML stylesheet "reformat" the XML content ?

Suppose I have a XML file and its schema, I want to generate a Java Object tree that is like the original XML schema but slightly different. So I guess I can use DOM or SAX to do the work. If I use JAXB or Castor I may have it problem as I want a different Object struture..

So without knowing too much about XML, here is what I am thinking --- Can I use some XML stylesheet stuff to "alter" the original XML and generate a XML that matches to my desired object struture ? If that's possible, then the second step is to use JXAB or Castor to work on the altered XML file and get the object tree. Does this make sense ?

Yes. However, you will have to author the modified XML Schema that JAXB needs. XSLT will only transforms documents (transformation of the XML Schema would require a separate XSLT � there is no point to that).

For an intro to XSLT see sample chapter 15 from Elliotte Rusty Harold's XML 1.1 Bible.

Writing complex style-sheets can be difficult as XSLT is more like a functional programming (FP) language (rather than procedural or object-oriented). Also it is easy to produce transforms that do not perform well (until you start thinking in FP terms)