Criteria with Projection

Criteria criteria = session.createCriteria(Employee.class);
Projection projection = Projections.property(“firstName”);
criteria.setProjection(projection);
List list = criteria.list();

Criteria criteria = session.createCriteria(Employee.class);
Projection projection1 = Projections.property(“firstName”);
Projection projection2 = Projections.property(“salary”);
Projection projection3 = Projections.property(“age”);

ProjectionList projectionList = Projections.projectionList();
projectionList.add(projection1);
projectionList.add(projection2);
projectionList.add(projection3);
criteria.setProjection(projectionList);
List list = criteria.list();

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>HibernateProjections</groupId>
  <artifactId>HibernateProjections</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>HibernateProjections</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>

    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
     <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->
		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-core</artifactId>
			<version>5.2.6.Final</version>
		</dependency>
		<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>6.0.5</version>
		</dependency>

  </dependencies>
</project>

package com.kb.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="Employee")
public class Employee {
	@Id
	@GeneratedValue(strategy = GenerationType.SEQUENCE)
	@Column(name = "Employee_Id")
	private int employeeId;
	
	@Column(name = "FirstName")
	private String firstName;
	
	@Column(name = "LastName")
	private String lastName;
	
	@Column(name = "Age")
	private int age;
	
	@Column(name = "Education")
	private String education;
	
	@Column(name = "Salary")
	private int salary;
	
	public int getEmployeeId() {
		return employeeId;
	}
	public void setEmployeeId(int employeeId) {
		this.employeeId = employeeId;
	}
	public String getFirstName() {
		return firstName;
	}
	public void setFirstName(String firstName) {
		this.firstName = firstName;
	}
	public String getLastName() {
		return lastName;
	}
	public void setLastName(String lastName) {
		this.lastName = lastName;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	public String getEducation() {
		return education;
	}
	public void setEducation(String education) {
		this.education = education;
	}
	public int getSalary() {
		return salary;
	}
	public void setSalary(int salary) {
		this.salary = salary;
	}
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
       "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
       "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

	<session-factory>

		<!-- Database connection properties -->
		<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
		<property name="connection.url">jdbc:mysql://localhost/javainsimpleway</property>
		<property name="connection.username">root</property>
		<property name="connection.password">root</property>

		<!-- JDBC connection pool (using the built-in) -->
		<property name="connection.pool_size">100</property>

		<!-- SQL dialect -->
		<property name="dialect">org.hibernate.dialect.MySQLDialect</property>

		<!-- Disable the second-level cache -->
		<property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property>

		<!-- Echo all executed SQL to stdout -->
		<property name="show_sql">true</property>

		<!-- Format the generated Sql -->
		<property name="format_sql">false</property>

		<!-- Dont Drop and re-create the database schema on startup,Just update 
			it -->
		<property name="hbm2ddl.auto">update</property>

		<mapping class="com.kb.model.Employee" />

	</session-factory>

</hibernate-configuration>

package com.kb.util;

import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class HibernateUtil {
	private static final SessionFactory sessionFactory = buildSessionFactory();

    private static SessionFactory buildSessionFactory() {
        try {
            // Create the SessionFactory from hibernate.cfg.xml
            return new Configuration().configure().buildSessionFactory();
        } catch (Throwable ex) {
            // Make sure you log the exception to track it
            System.err.println("SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
    
    public static void shutdown() {
    	// Optional but can be used to Close caches and connection pools
    	getSessionFactory().close();
    }

}

package com.kb.db;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;

import com.kb.model.Employee;
import com.kb.util.HibernateUtil;

public class PopulateData {
public static void main(String[] args) {

	// Get session factory using Hibernate Util class
	SessionFactory sf = HibernateUtil.getSessionFactory();
	// Get session from Sesson factory
	Session session = sf.openSession();

	// Begin transaction
	Transaction t = session.beginTransaction();
	
	//Create Employee  data
	Employee employee1 = new Employee();
	employee1.setFirstName("John");
	employee1.setLastName("KC");
	employee1.setAge(28);
	employee1.setEducation("PG");
	employee1.setSalary(25000);
	
	Employee employee2 = new Employee();
	employee2.setFirstName("Jacob");
	employee2.setLastName("JC");
	employee2.setAge(30);
	employee2.setEducation("PG");
	employee2.setSalary(30000);
	
	Employee employee3 = new Employee();
	employee3.setFirstName("Martin");
	employee3.setLastName("A");
	employee3.setAge(24);
	employee3.setEducation("UG");
	employee3.setSalary(20000);
	
	Employee employee4 = new Employee();
	employee4.setFirstName("Peter");
	employee4.setLastName("M");
	employee4.setAge(25);
	employee4.setEducation("UG");
	employee4.setSalary(22000);
	
	Employee employee5 = new Employee();
	employee5.setFirstName("Roshan");
	employee5.setLastName("B");
	employee5.setAge(29);
	employee5.setEducation("PG");
	employee5.setSalary(45000);
	
	
	session.save(employee1);
	session.save(employee2);
	session.save(employee3);
	session.save(employee4);
	session.save(employee5);

	// Commit the transaction and close the session
	t.commit();
	
	session.close();
	System.out.println("successfully persisted Employee details");

   }

}

package com.kb.db;

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

import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.criterion.Projection;
import org.hibernate.criterion.ProjectionList;
import org.hibernate.criterion.Projections;
import org.hibernate.criterion.Restrictions;

import com.kb.model.Employee;
import com.kb.util.HibernateUtil;

public class ProjectionExample {
	@SuppressWarnings("deprecation")
	public static void main(String[] args) {
		SessionFactory sf = HibernateUtil.getSessionFactory();
		Session session = sf.openSession();

		Criteria criteria = session.createCriteria(Employee.class);
		Projection projection = Projections.property("firstName");
		criteria.setProjection(projection);
		List<String> firstNameList = criteria.list();
		System.out.println("All Employee records with only first name column");
		for (String firstName : firstNameList) {
			System.out.println("First Name :" + firstName);
		}

		criteria = session.createCriteria(Employee.class);
		Projection projection1 = Projections.property("firstName");
		Projection projection2 = Projections.property("salary");
		Projection projection3 = Projections.property("age");

		ProjectionList projectionList = Projections.projectionList();
		projectionList.add(projection1);
		projectionList.add(projection2);
		projectionList.add(projection3);

		criteria.setProjection(projectionList);

		List empList = criteria.list();

		System.out.println("All the empoyees with first name,salary and age columns");
		Iterator iterator = empList.iterator();

		while (iterator.hasNext()) {
			Object[] obj = (Object[]) iterator.next();
			System.out.println("First Name" + obj[0] + " Salary : " + obj[1] + " Age : " + obj[2]);
		}

		criteria = session.createCriteria(Employee.class);
		criteria.setProjection(Projections.rowCount());
		List<Long> result = criteria.list();
		System.out.println("Total number of employees :" + result);

		criteria = session.createCriteria(Employee.class);
		double sumSalary = (Long)               
                    session.createCriteria(Employee.class).setProjection(Projections.sum("salary")).uniqueResult();
		System.out.println("Sum of Salary of all employees : " + sumSalary);

		// Adding both restrictions and projection on criteria
		criteria = session.createCriteria(Employee.class);
		criteria.add(Restrictions.gt("age", 25));
		criteria.setProjection(projectionList);
		empList = criteria.list();
		Iterator iterator1 = empList.iterator();
                System.out.println("All employees whose age is greater than 25");
		while (iterator1.hasNext()) {
			Object[] obj = (Object[]) iterator1.next();
			System.out.println("First Name" + obj[0] + " Salary : " + obj[1] + " Age : " + obj[2]);
		}

		session.close();
	}

}