Automatic random PIN generation has been all the more common now, especially in mobile applications. There is a very
good utility around by Stephen Ostermiller, that lets you generate random sequences of
arbitrary length and arbitrary alphabets. You can download the latest Ostermiller Utils from
http://ostermiller.org/utils/ostermillerutils106_00.jar
and then use it directly from command line (java -classpath utils.jar com.Ostermiller.util.RandPass), or more
commonly through your Java application:
String pass = new RandPass(new char[]{'A','B','C'}).getPass(8)