Is there a good example Debian package?
There are many Debian packages of both Java applications and libraries. These may serve as an good starting point, as it can serve as an example for making a new Debian package. A good start would be to check out the pkg-java project on Alioth: http://pkg-java.alioth.debian.org/. Note that there are many ways to make a Debian package, making use of Ant or Makefiles does not really matter. But, some tips for good practice are given on the pkg-java page: http://pkg-java.alioth.debian.org/developers.html#rules and http://pkg-java.alioth.debian.org/building.html.