I always thought this was a really slick way of storing a huge number of on/off flags (i.e. newsgroup user preferences such as read/unread). Anyway, you should be able to create a bit mask (represented as a String) and simply do an XOR against your long String. Don't have time to get into the details but that the gist of it.
i.e.
String group12345Read = "GsjhdufJSKJ";
String userPrefs = "YUAD*sddf76fHS*fhd"
if( (group12345Read | userPrefs) == 1 ) {
// they have read this one;
}
Check this out.
http://www.vipan.com/htdocs/bitwisehelp.html Sean