I don't have the book in front of me, but I'm assuming that:
compareTo(DVDInfo d) is a method inside of DVDInfo, andDVDInfo has a field called "title"If these assumptions are correct, then compareTo(DVDInfo d) is comparing
"this" instance of DVDInfo to some
other instance of DVDInfo referenced by "d". This comparison is done by comparing the titles of these two instances, where "title" is this.title, and d.getTitle represents the title of the other instance.
Further, I would assume that "title" is a
String, in which case it is String's compareTo method that is invoked for the comparison.