Example of @ElementCollection in Hibernate Annotation

package com.concretepage.persistence;

import java.io.Serializable;

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

@Entity
@Table(name="student")
public class Student implements Serializable {
	private static final long serialVersionUID = 1L;

	@Id
	@Column(name="student_id")
	private int studentId;
	
	@Column(name="student_name")
	private String studentName;
	
	@Column(name="college_id")
	private int collegeId;

	public Student(int studentId,String studentName,int collegeId){
		this.studentId=studentId;
		this.studentName=studentName;
		this.collegeId=collegeId;
	}

	public int getStudentId() {
		return studentId;
	}

	public void setStudentId(int studentId) {
		this.studentId = studentId;
	}

	public String getStudentName() {
		return studentName;
	}

	public void setStudentName(String studentName) {
		this.studentName = studentName;
	}
	
	public int getCollegeId() {
		return collegeId;
	}

	public void setCollegeId(int collegeId) {
		this.collegeId = collegeId;
	}

}
 

package com.concretepage.persistence;

import java.io.Serializable;
import java.util.Set;

import javax.persistence.CollectionTable;
import javax.persistence.Column;
import javax.persistence.ElementCollection;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.Table;

@Entity
@Table(name="college")
public class College implements Serializable {
	private static final long serialVersionUID = 1L;
	@Id
	@Column(name="college_id")
    private int collegeId;	
	
	@Column(name="name")
	private String collegeName;
	
	@ElementCollection
	@CollectionTable(name="student", joinColumns=@JoinColumn(name="college_id"))
	@Column(name="student_name")
	private Set<String> students;
	 
	public College(int collegeId,String collegeName){
		this.collegeId=collegeId;
		this.collegeName=collegeName;
	}
	
	public Set<String> getStudents() {
		return students;
	}

	public void setStudents(Set<String> students) {
		this.students = students;
	}

	public int getCollegeId() {
		return collegeId;
	}

	public void setCollegeId(int collegeId) {
		this.collegeId = collegeId;
	}

	public String getCollegeName() {
		return collegeName;
	}

	public void setCollegeName(String collegeName) {
		this.collegeName = collegeName;
	}
}
 

<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
  <session-factory>
    <property name="hibernate.connection.url">
    jdbc:mysql://localhost:3306/hibernate</property>
    <property name="hibernate.connection.username">root</property>
    <property name="hibernate.connection.password"></property>
    <property name="hibernate.connection.pool_size">10</property>
    <property name="show_sql">true</property>
    <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
    <property name="hibernate.hbm2ddl.auto">update</property>
    <mapping class="com.concretepage.persistence.Student"/>
    <mapping class="com.concretepage.persistence.College"/>

  </session-factory>
</hibernate-configuration>
 

package com.concretepage.util;
import java.util.Set;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import com.concretepage.persistence.College;
import com.concretepage.persistence.Student;

public class HibernateUtil {
	private static final SessionFactory concreteSessionFactory;
	    static {
	        try {
	            concreteSessionFactory = new AnnotationConfiguration()
	                    .configure().buildSessionFactory();
	        } catch (Throwable ex) {
	            throw new ExceptionInInitializerError(ex);
	        }
	    }
	    public static Session getSession()
	            throws HibernateException {
	        return concreteSessionFactory.openSession();
	    }
	    
	    public static void main(String... args){
	    	Session session=getSession();
	    	session.beginTransaction();
	    	
	    	College c=new College(1,"S.S.P.C");
	    	session.persist(c);
	        Student s1=new Student(1,"Atul",1);
	        session.persist(s1);
	        Student s2=new Student(2,"Saurabh",1);
	        session.persist(s2);
	    		    	
	       	session.getTransaction().commit();
	       	session.refresh(c);
	       	College ob=(College)session.get(College.class, new Integer(1));
	       	Set<String> names=ob.getStudents();
	       	for(String s:names){
	       		System.out.println(s);	
	       	}
	    }
	}
 

Hibernate: insert into college (name, college_id) values (?, ?)
Hibernate: insert into student (college_id, student_name, student_id) values (?, ?, ?)
Hibernate: insert into student (college_id, student_name, student_id) values (?, ?, ?)
Hibernate: select college0_.college_id as college1_1_0_, college0_.name as name1_0_ from college college0_ where college0_.college_id=?
Hibernate: select students0_.college_id as college2_1_0_, students0_.student_name as student3_0_ from student students0_ where students0_.college_id=?
Saurabh
Atul