GeoTools is an open source Java library that provides tools for geospatial data.
Find GeoTools info at http://geotools.org/
If your question is about a programming issue using GeoTools then you should ask on http://stackoverflow.com with a GeoTools tag, questions about geographic issues (with GeoTools) should be asked here.
In general a GeoTools question is expected to have a valid code sample in it, ideally this should be a small self contained program that can be run to test your problem.