Hibernate Delete or Remove an Entity Example

🎓 Top 15 Udemy Courses (80-90% Discount): My Udemy Courses - Ramesh Fadatare — All my Udemy courses are real-time and project oriented courses.

▶️ Subscribe to My YouTube Channel (178K+ subscribers): Java Guides on YouTube

▶️ For AI, ChatGPT, Web, Tech, and Generative AI, subscribe to another channel: Ramesh Fadatare on YouTube

In Hibernate, an entity can be removed from a database by calling the Session.delete() or Session.remove(). Using these methods, we can remove a transient or persistent object from the datastore.

This tutorial is upgraded to Hibernate framework 6 and Java 17.

Session.delete(Object object) Method

This method removes the persistent instance from the datastore. The argument may be an instance associated with the receiving Session or a transient instance with an identifier associated with an existing persistent state. This operation cascades to associated instances if the association is mapped with cascade="delete".

EntityManager.remove(Object entity)

This method removes the given entity instance from the database:

Hibernate Delete or Remove an Entity Complete Example

Let's create a Hibernate Maven application to demonstrate the usage of the Session.delete() and Session.remove() methods.

Technologies and tools used

• Hibernate 6.1.7.Final
• IDE - Eclipse
• Maven 3.5.3
• Java 17
• MySQL - 8.0.32

Development Steps

1. Create a Simple Maven Project
2. Project Directory Structure
3. Add jar Dependencies to pom.xml
4. Creating the JPA Entity Class(Persistent class)
5. Create a Hibernate configuration file - Java Configuration
6. Removing an entity using the delete() method
7. Removing an entity using the remove() method
8. Create the Main class and Run an Application

1. Create a Simple Maven Project

Use the How to Create a Simple Maven Project in Eclipse article to create a simple Maven project in Eclipse IDE.

2. Project Directory Structure

The project directory structure for your reference - 

3. Add jar Dependencies to pom.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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>net.javaguides.hibernate</groupId>
        <artifactId>hibernate-tutorial</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <artifactId>hibernate-remove-entity-example</artifactId>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <dependencies>
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.32</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>6.1.7.Final</version>
        </dependency>
    </dependencies>
    <build>
        <sourceDirectory>src/main/java</sourceDirectory>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.5.1</version>
                <configuration>
                    <source>17</source>
                    <target>17</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

4. Creating the JPA Entity Class(Persistent class)

Let's create a Student persistent class that is mapped to a database table.

A simple Persistent class should follow some rules:

• A no-arg constructor: It is recommended that you have a default constructor at least package visibility so that hibernate can create the instance of the Persistent class by newInstance() method.
• Provide an identifier property: It is better to assign an attribute as id. This attribute behaves as a primary key in a database.
• Declare getter and setter methods: The Hibernate recognizes the method by getter and setter method names by default.
• Prefer non-final class: Hibernate uses the concept of proxies, that depend on the persistent class. The application programmer will not be able to use proxies for lazy association fetching.

Create a Student entity class under net.javaguides.hibernate.entity package as follows.

package net.javaguides.hibernate.entity;

import jakarta.persistence.*;

@Entity
@Table(name = "student")
public class Student {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private int id;

    @Column(name = "first_name")
    private String firstName;

    @Column(name = "last_name")
    private String lastName;

    @Column(name = "email")
    private String email;

    public Student() {

    }

    public Student(String firstName, String lastName, String email) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.email = email;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    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 String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Override
    public String toString() {
        return "Student [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", email=" + email + "]";
    }
}

5. Create a Hibernate configuration file - Java Configuration

The HibernateUtil Java configuration file contains information about the database and mapping file.

HibernateUtil is a helper class to bootstrap hibernate SessionFactory.Add the Student entity to MetadataSources for mapping.

package net.javaguides.hibernate.util;

import java.util.Properties;

import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.cfg.Environment;
import org.hibernate.service.ServiceRegistry;

import net.javaguides.hibernate.entity.Student;

public class HibernateUtil {
    private static SessionFactory sessionFactory;
    public static SessionFactory getSessionFactory() {
        if (sessionFactory == null) {
            try {
                Configuration configuration = new Configuration();

                // Hibernate settings equivalent to hibernate.cfg.xml's properties
                Properties settings = new Properties();
                settings.put(Environment.DRIVER, "com.mysql.cj.jdbc.Driver");
                settings.put(Environment.URL, "jdbc:mysql://localhost:3306/hibernate_db?useSSL=false");
                settings.put(Environment.USER, "root");
                settings.put(Environment.PASS, "root");
      
                settings.put(Environment.SHOW_SQL, "true");

                settings.put(Environment.CURRENT_SESSION_CONTEXT_CLASS, "thread");

                settings.put(Environment.HBM2DDL_AUTO, "create-drop");

                configuration.setProperties(settings);

                configuration.addAnnotatedClass(Student.class);

                ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
                    .applySettings(configuration.getProperties()).build();

                sessionFactory = configuration.buildSessionFactory(serviceRegistry);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return sessionFactory;
    }
}

6. Removing an entity using the delete() method

The following example deletes transient and persistent objects from the datastore using the Session.delete() method.

package net.javaguides.hibernate.dao;

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

import net.javaguides.hibernate.entity.Student;
import net.javaguides.hibernate.util.HibernateUtil;

public class SessionDeleteExample {
    public void deleteStudent(int id) {
        Transaction transaction = null;
        try (Session session = HibernateUtil.getSessionFactory().openSession()) {
            // start a transaction
            transaction = session.beginTransaction();

            // Delete a persistent object
            Student student = session.get(Student.class, id);
            if (student != null) {
                session.delete(student);
                System.out.println("student 1 is deleted");
            }

            // Delete a transient object
            Student student2 = new Student();
            student2.setId(2);
            session.delete(student2);
            System.out.println("Student 2 is deleted");

            // commit transaction
            transaction.commit();
        } catch (Exception e) {
            if (transaction != null) {
                transaction.rollback();
            }
            e.printStackTrace();
        }
    }
}

7. Removing an entity using the remove() method

The following example deletes transient and persistent objects from the datastore using Session.remove() method.

package net.javaguides.hibernate.dao;

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

import net.javaguides.hibernate.entity.Student;
import net.javaguides.hibernate.util.HibernateUtil;

public class SessionRemoveExample {
    public void removeStudent(int id) {
        Transaction transaction = null;
        try (Session session = HibernateUtil.getSessionFactory().openSession()) {
            // start a transaction
            transaction = session.beginTransaction();

            // Delete a persistent object
            Student student = session.get(Student.class, id);
            if (student != null) {
                session.remove(student);
                System.out.println("student 1 is deleted");
            }

            // Delete a transient object
            Student student2 = new Student();
            student2.setId(2);
            session.remove(student2);
            System.out.println("Student 2 is deleted");

            // commit transaction
            transaction.commit();
        } catch (Exception e) {
            if (transaction != null) {
                transaction.rollback();
            }
            e.printStackTrace();
        }
    }
}

8. Create the main App class and Run an Application

Let's test Hibernate application to connect the MySQL database.

package net.javaguides.hibernate;

import net.javaguides.hibernate.dao.SessionDeleteExample;
import net.javaguides.hibernate.dao.SessionRemoveExample;
import net.javaguides.hibernate.dao.SessionSaveExample;
import net.javaguides.hibernate.entity.Student;

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

        // first save few records to database
        SessionSaveExample studentDao = new SessionSaveExample();
        Student s1 = new Student("Ramesh", "Fadatare", "rameshfadatare@javaguides.com");
        Student s2 = new Student("John", "Cena", "johncena@javaguides.com");
        studentDao.saveStudent(s1);
        studentDao.saveStudent(s2);

        // delete student
        SessionDeleteExample deleteExample = new SessionDeleteExample();
        deleteExample.deleteStudent(1);

        // delete second student
        SessionRemoveExample persistExample = new SessionRemoveExample();
        persistExample.removeStudent(2);
    }
}

Output

GitHub Repository

The complete source code of this article is available on my GitHub Repository - https://github.com/RameshMF/Hibernate-ORM-Tutorials

Conclusion

In this article, we have created a simple hibernate application to demonstrate the use of Session.delete() and Session.remove() methods.

You can learn more about Hibernate ORM Framework at Hibernate Tutorial.

My Top and Bestseller Udemy Courses. The sale is going on with a 70 - 80% discount. The discount coupon has been added to each course below:

Build REST APIs with Spring Boot 4, Spring Security 7, and JWT

🆕 High-Demand 80–90% OFF

[NEW] Learn Apache Maven with IntelliJ IDEA and Java 25

🆕 High-Demand 80–90% OFF

ChatGPT + Generative AI + Prompt Engineering for Beginners

🚀 Trending Now 80–90% OFF

Spring 7 and Spring Boot 4 for Beginners (Includes 8 Projects)

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Building Real-Time REST APIs with Spring Boot - Blog App

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Building Microservices with Spring Boot and Spring Cloud

🌟 Top Rated 80–90% OFF
Available in Udemy for Business

Java Full-Stack Developer Course with Spring Boot and React JS

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Build 5 Spring Boot Projects with Java: Line-by-Line Coding

🌟 Top Rated 80–90% OFF

Testing Spring Boot Application with JUnit and Mockito

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Spring Boot Thymeleaf Real-Time Web Application - Blog App

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Master Spring Data JPA with Hibernate

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Spring Boot + Apache Kafka Course - The Practical Guide

🎓 Student Favorite 80–90% OFF
Available in Udemy for Business

Java Testing: Mastering JUnit 5 Framework

🆕 New 80–90% OFF

Reactive Programming in Java: Spring WebFlux and Testing

🌟 Top Rated 80–90% OFF

Spring Boot + RabbitMQ Course - The Practical Guide

🌟 Top Rated 80–90% OFF
Available in Udemy for Business

Functional Programming in Java (Includes Java Collections)

🎓 Student Favorite 80–90% OFF

ChatGPT for Java Developers: Boost Your Productivity with AI

🚀 Trending Now 80–90% OFF