This brief code example checks to see whether user_to_check (a Twitter username as a String) is following the Twitter account twitter_username. The boolean is_user_following will be true if there is a follow.
The twitter object represents a twitter4j.Twitter class preconfigured with authentication details.
Relationship to_other_user = twitter.showFriendship(twitter_username, user_to_check);
boolean is_user_following = to_other_user.isTargetFollowingSource();