package tutorial.dev.tree;import java.io.Serializable;import java.sql.Connection;import java.util.HashSet;import java.util.Iterator;import java.util.Set;import net.sf.hibernate.HibernateException;import net.sf.hibernate.Session;import net.sf.hibernate.SessionFactory;import net.sf.hibernate.Transaction;import net.sf.hibernate.cfg.Configuration;public class TreeDemo {	public static void main(String[] args) {		try {			new TreeDemo();		} catch(HibernateException he) {			he.printStackTrace();		}	}		public TreeDemo() throws HibernateException {		Configuration config = new Configuration();		// add the classes you want to persist		// make sure the mapping files are on the classpath		config.addClass(Friend.class);				SessionFactory sf = config.buildSessionFactory();			Session sess = sf.openSession();		Transaction tx = null;		Connection con = null;		// store the orderlist and all products		Serializable id = null;						Friend a = new Friend("a");		Friend b = new Friend("b");		Friend c = new Friend("c");		Friend d = new Friend("d");		Friend e = new Friend("e");		Friend f = new Friend("f");		Friend g = new Friend("g");		Friend h = new Friend("h");						a.getFriends().add(b);		a.getFriends().add(c);		b.getFriends().add(d);		b.getFriends().add(e);		b.getFriends().add(f);		d.getFriends().add(g);		d.getFriends().add(h);						e.getFriends().add(h);		c.getFriends().add(f);						a = new Friend("Root");		makeFriends(a);				try {			tx = sess.beginTransaction();			sess.save(a);			tx.commit();		} catch (HibernateException he) {		    if (tx!=null) tx.rollback();		    throw he;		} finally {		    sess.close();		}		Set friends = new HashSet();		sess = sf.openSession();		try {			tx = sess.beginTransaction();			Friend root = (Friend)sess.get(Friend.class, a.getId());			friends(root, friends, 2);			tx.commit();		} catch (HibernateException he) {		    if (tx!=null) tx.rollback();		    throw he;		} finally {		    sess.close();		}				for (Iterator iter = friends.iterator(); iter.hasNext();) {			Friend friend = (Friend) iter.next();			System.out.println("Friend: " + friend.getName());		}		System.out.println("FriendCount: " + friends.size());			}				protected void friends(Friend root, Set friends, int distance) {		if (distance > 0) {			friends.addAll(root.getFriends());			for (Iterator iter = root.getFriends().iterator(); iter.hasNext();) {				Friend friend = (Friend) iter.next();				friends(friend, friends, distance -1);			}		}	}	private int level = 0;	private int count = 0;	protected void makeFriends(Friend root) {		System.out.println("Level: " + level + " -> " + count);		if (level < 3) {						for(int i = 0; i < 10; i++) {				if (Math.random() < 0.6) {				Friend f = new Friend(root.getName() +"/"+ i);				count++;				root.getFriends().add(f);				level++;				makeFriends(f);				level--;				}			}		} else {					}		}		}