What is convenience method in java?

Question

i generate hibernate pojos + hybernate mapping + dao. in dao class i have some doubt in coding please clear.
package org.triology.blog.hibernate;
import org.triology.blog.GenericDAO;
import java.io.Serializable;
import java.lang.reflect.ParameterizedType;
import java.util.List;
import java.util.Map;
import org.hibernate.Criteria;
import org.hibernate.FlushMode;
import org.hibernate.Query;
import org.hibernate.LockMode;
import org.hibernate.Session;
import org.hibernate.criterion.Restrictions;
import org.hibernate.criterion.Criterion;
import org.hibernate.criterion.Example;
* Generated at Wed Jul 30 16:57:35 IST 2008
* @author Salto-db Generator v1.0.16 / Pojos + Hibernate mapping + Generic DAO
* @see http://www.hibernate.org/328.html
public abstract class AbstractHibernateDAO<T, ID extends Serializable> implements GenericDAO<T, ID> {
private Session session;
private Class<T> persistentClass;
public AbstractHibernateDAO() {
this.persistentClass = (Class<T>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];
public void setSession(Session session) {
this.session = session;
protected Session getSession() {
if (session == null)
session = HibernateUtil.getSessionFactory().getCurrentSession();
return session;
public Class<T> getPersistentClass() {
return persistentClass;
@SuppressWarnings("unchecked")
public T getById(ID id) {
return (T) getSession().get(getPersistentClass(), id);
@SuppressWarnings("unchecked")
public T getById(ID id, boolean lock) {
if (lock) {
return (T) getSession().get(getPersistentClass(), id,
LockMode.UPGRADE);
} else
return getById(id);
@SuppressWarnings("unchecked")
public T loadById(ID id) {
return (T) getSession().load(getPersistentClass(), id);
public void save(T entity) {
getSession().save(entity);
public void update(T entity) {
getSession().update(entity);
public void saveOrUpdate(T entity) {
getSession().saveOrUpdate(entity);
public void delete(T entity) {
getSession().delete(entity);
public void deleteById(ID id)      {
getSession().delete(loadById(id));
@SuppressWarnings("unchecked")
public List<T> findAll() {
return findByCriteria();
* Use this inside subclasses as a convenience method.
@SuppressWarnings("unchecked")
protected List<T> findByCriteria(Criterion... criterion) {
Criteria crit = getSession().createCriteria(getPersistentClass());
for (Criterion c : criterion) {
crit.add(c);
return crit.list();
* Find by criteria.
@SuppressWarnings("unchecked")
public List<T> findByCriteria(Map criterias) {
Criteria criteria = getSession().createCriteria(getPersistentClass());
criteria.add(Restrictions.allEq(criterias));
return criteria.list();
* This method will execute an HQL query and return the number of affected entities.
protected int executeQuery(String query, String namedParams[],     Object params[]) {
Query q = getSession().createQuery(query);
if (namedParams != null) {
for (int i = 0; i < namedParams.length; i++) {
q.setParameter(namedParams, params[i]);
return q.executeUpdate();
protected int executeQuery(String query) {
return executeQuery(query, null, null);
* This method will execute a Named HQL query and return the number of affected entities.
protected int executeNamedQuery(String namedQuery, String namedParams[],     Object params[]) {
Query q = getSession().getNamedQuery(namedQuery);
if (namedParams != null) {
for (int i = 0; i < namedParams.length; i++) {
q.setParameter(namedParams[i], params[i]);
return q.executeUpdate();
protected int executeNamedQuery(String namedQuery) {
return executeNamedQuery(namedQuery, null, null);
@SuppressWarnings("unchecked")
public List<T> findByExample(T exampleInstance, String[] excludeProperty) {
Criteria crit = getSession().createCriteria(getPersistentClass());
Example example = Example.create(exampleInstance).excludeZeroes().enableLike().ignoreCase();
for (String exclude : excludeProperty) {
example.excludeProperty(exclude);
crit.add(example);
return crit.list();
in above class my doubt is
* Use this inside subclasses as a convenience method.
@SuppressWarnings("unchecked")
protected List<T> findByCriteria(Criterion... criterion) {
Criteria crit = getSession().createCriteria(getPersistentClass());
for (Criterion c : criterion) {
crit.add(c);
return crit.list();
why we pass findByCriteria parameter end with three dots (Criterian...)

Answer 1

When you post code, please use code tags as described in [Formatting tips|http://forum.java.sun.com/help.jspa?sec=formatting] on the message entry page. It makes it much easier to read.
Also try to strip the example code down to just what you want to show.
why we pass findByCriteria parameter end with three dots (Criterian...)
varargs
Please do not [cross post|http://forums.sun.com/thread.jspa?threadID=5319163]. Finding out that someone else has already answered this question in a different thread is very irritating, and will put people off answering you future queries.
Edited by: mlk on 31-Jul-2008 09:14