Hibernate Criteria Distinct

The Hibernate Criteria Distinct API search and display the distinct result

Consider the following SQL

SELECT DISTINCT name FROM student WHERE roll_no=2;

The above SQL will return the  distinct name from the student table. The same thing can be written using Criteria distinct API as follows

Criteria criteria = session.createCriteria(Student.class);
	criteria.add(Restrictions.eq("rollNo",2));
	criteria.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);
        List list = criteria.list();

Consider the example given below

DistinctCriteria.java

package net.roseindia.main;

import java.util.Iterator;
import java.util.List;

import net.roseindia.bean.Student;
import net.roseindia.util.HibernateUtil;

import org.hibernate.Criteria;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.criterion.Restrictions;

public class DistinctCriteria {

	@SuppressWarnings("unchecked")
	public static void main(String[] args) {

		Session session = HibernateUtil.getSessionFactory().openSession();

		Object object;

		try {
			// Creating a Criteria instance

			Criteria criteria = session.createCriteria(Student.class);
			System.out.println("\n");
			criteria.add(Restrictions.eq("rollNo",2));
		    criteria.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);
		    List list = criteria.list();
			Iterator itr = list.iterator();
		    
			if (list.size() == 0) {
				System.out.println("No Result Found !");
			}
			while (itr.hasNext()) {
				object = (Object) itr.next();
				System.out.printf("\t");
				System.out.println(((Student) object).getRollNo()+"\t"+ ((Student) object).getName()+"\t"+ ((Student) object).getCourse()+"\t"+ ((Student) object).getAddress());
				}

		} catch (HibernateException e) {

			e.printStackTrace();
		} finally {
			session.close();
		}

	}
}

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