In this section, you will learn about the hibernate projection with an example.

Hibernate Projections (rowCount or countDistinct)

In this section, you will learn about the hibernate projection with an example. 
Projection Interface: This is an interface that extends the Serializable. An object-oriented representation of a query result set projection in aCriteria query. Built-in projection types are provided by the Projections factory class. The Projection interface might be implemented by application classes that define custom projections.
The following example to count the total number of rows and distinct rows to use theProjections.rowCount() and Projections.countDistinct() method. 
Table Name: Insurance


Here is the code of program:

package roseindia.tutorial.hibernate; import java.util.Iterator; import java.util.List; import org.hibernate.Criteria; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; import org.hibernate.criterion.Projections; public class hibernateProjectionExample {   /**  * @param args  */   public static void main(String[] args) {   // TODO Auto-generated method stub   Session sess = null;   try{   SessionFactory fact = new    Configuration().configure().buildSessionFactory();   sess = fact.openSession();   Criteria crit = sess.createCriteria(Insurance.class);   crit.setProjection(Projections.rowCount());   List result = crit.list();   System.out.println("No. of rows: "+result);   crit.setProjection(Projections.distinct    (Projections.countDistinct("insuranceName")));   List distList = crit.list();   System.out.println("Distinct Count:  "+ distList);   }   catch(Exception e){   System.out.println(e.getMessage());   }   } }

Download this Code.
Output:

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).log4j:WARN Please initialize the log4j system properly.Hibernate: select count(*) as y0_ from insurance this_ No. of rows: [7] Hibernate: select distinct count(distinct this_.insurance_name) as y0_ from insurance this_ Distinct Count: [5]