Hibernate – SortedSet Mapping

Last Updated : 06 Jan, 2023

SortedSet can be viewed in a group of elements and they do not have a duplicate element and ascending order is maintained in its elements. By using <set> elements we can use them and the entity should have a Sortedset of values. As an example, we can have a freelancer who works for multiple companies on a shift basis. Here also the one-to-many relationship is seen as a freelancer can belong to multiple (many) companies.

Example Project

Project Structure:

This is a maven project. Let us see pom.xml

pom.xml

XML

<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 
                             https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>HibernateSortedSetMapping</groupId>
  <artifactId>HibernateSortedSetMapping</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <build>
    <sourceDirectory>src</sourceDirectory>
    <resources>
      <resource>
        <directory>src</directory>
        <excludes>
          <exclude>**/*.java</exclude>
        </excludes>
      </resource>
    </resources>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.8.1</version>
        <configuration>
          <release>9</release>
        </configuration>
      </plugin>
    </plugins>
  </build>
  <dependencies>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.4.15.Final</version>
        </dependency>
        <!-- As we are connecting with MySQL, this is needed -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.34</version>
        </dependency>
    </dependencies>
    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>
</project>

Let us start with POJO classes

Freelancer.java

Java

import java.util.SortedSet;
 
public class Freelancer {
    // data members
    private int freelancerId;
    private String freelancerName;
    private int freelancerAge;
    private int pricePerHour;
    // As one freelancer works for multiple companies, let
    // us have that as SortedSet here for companies
    private SortedSet companies;
 
    public int getFreelancerId() { return freelancerId; }
    public void setFreelancerId(int freelancerId)
    {
        this.freelancerId = freelancerId;
    }
    public String getFreelancerName()
    {
        return freelancerName;
    }
    public void setFreelancerName(String freelancerName)
    {
        this.freelancerName = freelancerName;
    }
    public int getFreelancerAge() { return freelancerAge; }
    public void setFreelancerAge(int freelancerAge)
    {
        this.freelancerAge = freelancerAge;
    }
    public int getPricePerHour() { return pricePerHour; }
    public void setPricePerHour(int pricePerHour)
    {
        this.pricePerHour = pricePerHour;
    }
    public SortedSet getCompanies() { return companies; }
    public void setCompanies(SortedSet companies)
    {
        this.companies = companies;
    }
    // no argument constructor
    public Freelancer() {}
    // argument constructor
    public Freelancer(String freelancerName,
                      int freelancerAge, int pricePerHour)
    {
        this.freelancerName = freelancerName;
        this.freelancerAge = freelancerAge;
        this.pricePerHour = pricePerHour;
    }
}

Company.java

Java

public class Company implements Comparable<Company> {
    private int companyId;
    private String companyName;
    public int getCompanyId() { return companyId; }
 
    public void setCompanyId(int companyId)
    {
        this.companyId = companyId;
    }
 
    public String getCompanyName() { return companyName; }
 
    public void setCompanyName(String companyName)
    {
        this.companyName = companyName;
    }
 
    public Company(String companyName)
    {
        this.companyName = companyName;
    }
 
    public Company() {}
 
    @Override
    // This method has to be implemented as we are following
    // SortedSet
    public int compareTo(Company company)
    {
        if (company == null) {
            return -1;
        }
        Comparable company1 = this.getCompanyName();
        Comparable company2 = company.getCompanyName();
        if (company1 == null) {
            return 1;
        }
        else if (company2 == null) {
            return -1;
        }
        else {
            return company1.compareTo(company2);
        }
    }
}

Let us see the configuration files

hibernate.cfg.xml

XML

<?xml version='1.0' encoding='UTF-8'?>  
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
             "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
     
          <!--  As we are connecting mysql, those driver classes, database name, 
              username and password are specified
              Please change the information as per your requirement -->
       
        <!-- This property creates table in MySQL automatically
             according to the specifications 
             given in mapping resource file which in turn maps to the POJO class -->
        <property name="hbm2ddl.auto">update</property>  
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/geeksforgeeks?serverTimezone=UTC</property>        
        <property name="connection.username">root</property>
        <property name="connection.password">admin</property>
         
          <!-- Helps to show the correct sql for each 
             and every hibernate operation -->
        <property name="show_sql">true</property>
         
           <!--  We are going to connect language.hbm.xml and 
               book.hbm.xml which has the table information 
               about programmingLanguages and book which is present in mysql -->
         <mapping resource="freelancer.hbm.xml"/>
        <mapping resource="company.hbm.xml"/>
       
    </session-factory>
</hibernate-configuration>

freelancer.hbm.xml

XML

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-mapping SYSTEM
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> 
<hibernate-mapping> 
   
  <!-- In MySQL, 'freelancer' table is created if it is not there and it
       should have 4 attributes namely freelancerId, freelancerName, 
       freelancerAge  and pricePerHour -->
 <class name="com.gfg.sortedsetmapping.pojo.Freelancer" table="freelancer">
  <id name="freelancerId" type="int" column="freelancerId">
    <generator class="native"></generator>
  </id> 
  <property name="freelancerName" column="freelancerName" type="string"/>
  <property name="freelancerAge" column="freelancerAge" type="int"/>
  <property name="pricePerHour" column="pricePerHour" type="int"/>
   
       <!-- We are following SortedSet Pattern. Hence should provide 'set' and also 'sort' nature
          Here one to many relationship is followed and it denote a key column as well -->
  <set name="companies" cascade="all"  sort="natural">
       <key column="freelancerId"/>
       <one-to-many class="com.gfg.sortedsetmapping.pojo.Company"/>
  </set> 
 </class> 
   
</hibernate-mapping>

company.hbm.xml

XML

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-mapping SYSTEM
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
  
    <!-- In MySQL, 'company' table is created if it is not there and it
         should have 2 attributes namely companyId and companyName -->
<hibernate-mapping> 
   
  <class name="com.gfg.sortedsetmapping.pojo.Company" table="company">
    <id name="companyId" type="int" column="companyId">
    <generator class="native"></generator>
    </id> 
    <property name="companyName" column="companyName" type="string"></property>
  </class>
   
</hibernate-mapping>

SortedSetMappingPatternOfStoringData.java

Java

import com.gfg.sortedsetmapping.pojo.Company;
import com.gfg.sortedsetmapping.pojo.Freelancer;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
 
public class SortedSetMappingPatternOfStoringData {
    private static SessionFactory factory;
 
    public static void main(String[] args)
    {
 
        try {
            factory = new Configuration()
                          .configure()
                          .buildSessionFactory();
        }
        catch (Throwable ex) {
            System.err.println(
                "Failed to create sessionFactory object."
                + ex);
            throw new ExceptionInInitializerError(ex);
        }
 
        // As one freelancer works for multiple companies,
        // via TreeSet we can represent that
        TreeSet companySet1 = new TreeSet();
        companySet1.add(new Company("Company A"));
        companySet1.add(new Company("Company B"));
 
        TreeSet companySet2 = new TreeSet();
        companySet2.add(new Company("Company A"));
        companySet2.add(new Company("Company C"));
        companySet2.add(new Company("Company E"));
 
        // Create the Freelancer object.
        Freelancer freelancer1
            = new Freelancer("Freelancer A", 20, 1000);
        freelancer1.setCompanies(
            companySet1); // Freelancer A associated to 2
        // companies
 
        Freelancer freelancer2
            = new Freelancer("Freelancer B", 20, 2000);
        freelancer2.setCompanies(
            companySet2); // Freelancer B associated to 2
        // companies
 
        SortedSetMappingPatternOfStoringData
            sortedMapMappingPatternOfStoringData
            = new SortedSetMappingPatternOfStoringData();
        // insert freelancer object.
        Integer freelancerId1
            = sortedMapMappingPatternOfStoringData
                  .addFreelancer(freelancer1);
 
        Integer freelancerId2
            = sortedMapMappingPatternOfStoringData
                  .addFreelancer(freelancer2);
 
        // show all Language and book details object.
        sortedMapMappingPatternOfStoringData
            .listFreelancerAndCompanyDetails();
    }
 
    public Integer addFreelancer(Freelancer freelancer)
    {
        Session session = factory.openSession();
        Transaction tx = null;
        Integer languageId = null;
        try {
            tx = session.beginTransaction();
            languageId = (Integer)session.save(freelancer);
            tx.commit();
        }
        catch (HibernateException e) {
            if (tx != null)
                tx.rollback();
            e.printStackTrace();
        }
        finally {
            session.close();
        }
        return languageId;
    }
 
    // Method to list all the freelancers and company detail
    public void listFreelancerAndCompanyDetails()
    {
        Session session = factory.openSession();
        Transaction tx = null;
 
        try {
            tx = session.beginTransaction();
            List<Freelancer> freelancers
                = session.createQuery("FROM Freelancer")
                      .list();
            for (Freelancer freelancer : freelancers) {
                System.out.println(
                    "Freelancer Name: "
                    + freelancer.getFreelancerName());
                System.out.println(
                    "Freelancer Age: "
                    + freelancer.getFreelancerAge());
                System.out.println(
                    "Price Per Hour: "
                    + freelancer.getPricePerHour());
                Set<Company> companies
                    = freelancer.getCompanies();
                for (Company company : companies) {
                    System.out.println(
                        "Company Name:"
                        + company.getCompanyName());
                }
            }
            tx.commit();
        }
        catch (HibernateException e) {
            if (tx != null)
                tx.rollback();
            e.printStackTrace();
        }
        finally {
            session.close();
        }
    }
}

On execution of the project.

Output:

Conclusion

The one-to-many relationship can be easily depicted via SortedSet and from the output, it is proved that no duplicate elements and ascending order is maintained in the output.

Suggest improvement

Hibernate - Difference Between List and Bag Mapping

Hibernate - SortedMap Mapping

Share your thoughts in the comments

Basics of Spring Framework

Software Setup and Configuration

Core Spring

Spring with REST API

Spring Data

Spring JDBC

Spring Hibernate

Spring AOP

Spring Security

Hibernate – SortedSet Mapping

Example Project

XML

Java

Java

XML

XML

XML

Java

Conclusion

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