Hibernate criteria query using avg()

You can calculate average of any numeric values in hibernate criteria by using projection. Projection is an interface and a class in ?org.hibernate.criterion?. For using Projection object in our Criteria, we have to call setProjection method

Example:

package net.roseindia.projection;

import java.util.*;

import net.roseindia.table.Employee;
import net.roseindia.util.HibernateUtil;
import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.criterion.Projections;

public class ProjectionAvg{
    public static void main(String[] args) {
        SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
        Session session = sessionFactory.openSession();
        Criteria criteria=session.createCriteria(Employee.class);

        criteria.setProjection(Projections.avg("salary"));
        List employeeList = (List)criteria.list();

        for(Object employee: employeeList){
            System.out.println(employee);
        }
            }
}

Output-

Hibernate: select avg(this_.salary) as y0_ from employee this_
68750.0

Description: Here we are calculating average of all employee salary by using

criteria.setProjection(Projections.avg("salary"))