XML Parser bug/error report

I'm looking for a tool that will report problems in XML files if not parsed
(e.g. what is wrong at what position in document ...). I'm using Java to
process the XML files. The best would be some Java APIs. The report should
be XML author oriented, not Java programmer oriented. The author of the XML
file should be able to correct the XML file by referring to the report.

Thanks.

Peiyun Jiang