Step-by-Step Implementation of Deleting an Entity in JPA
Step 1: First, we will create the JPA project using the Intellij Idea named as jpa-delete-entity-demo of the project.
Step 2: Now, we will add the below dependencies into the JPA project.
Dependencies:
<dependency>
<groupId>org.hibernate.orm</groupId>
<artifactId>hibernate-core</artifactId>
<version>6.0.2.Final</version>
</dependency>
<dependency>
<groupId>org.glassfish.jaxb</groupId>
<artifactId>jaxb-runtime</artifactId>
<version>3.0.2</version>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.28</version>
</dependency>
Once the project creation completed, then the file structure will look like the below image.
file structure
Step 3: Open persistance.xml and put the below code for the MYSQL database configuration of the database.
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<persistence xmlns="https://jakarta.ee/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="https://jakarta.ee/xml/ns/persistence https://jakarta.ee/xml/ns/persistence/persistence_3_0.xsd"
version="3.0">
<persistence-unit name="StudentPU">
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/example"/>
<property name="javax.persistence.jdbc.user" value="root"/>
<property name="javax.persistence.jdbc.password" value=""/>
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect"/>
<property name="hibernate.hbm2ddl.auto" value="update"/>
</properties>
</persistence-unit>
</persistence>
Step 4: Create the new Java package named as model in that package, create the new Entity Java class for the creation of the entity and it named as Student. Go to src > main > java > model > Student and put the below code.
package model;
import jakarta.persistence.Entity;
import jakarta.persistence.Id;
@Entity
public class Student {
@Id
private int id;
private String name;
private int age;
// Getters and setters
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
Step 5: Create the new Java package named as util in that package, create the new Entity Java class for the creation of the entity and it named as JPAUtil. Go to src > main > java > util > JPAUtil and put the below code.
package util;
import jakarta.persistence.EntityManager;
import jakarta.persistence.EntityManagerFactory;
import jakarta.persistence.Persistence;
public class JPAUtil {
private static final EntityManagerFactory emFactory;
static {
emFactory = Persistence.createEntityManagerFactory("StudentPU");
}
public static EntityManager getEntityManager() {
return emFactory.createEntityManager();
}
public static void close() {
emFactory.close();
}
}
Step 6: Create the new Java class and named as the MainApplication. Go to src > main > java > MainApplication and put the below code.
import jakarta.persistence.EntityManager;
import model.Student;
import util.JPAUtil;
public class MainApplication {
public static void main(String[] args) {
EntityManager entityManager = JPAUtil.getEntityManager();
entityManager.getTransaction().begin();
// Creating a new student
Student student = new Student();
student.setId(10);
student.setName("Syam Sunder");
student.setAge(20);
entityManager.persist(student);
entityManager.getTransaction().commit();
// Deleting the student
entityManager.getTransaction().begin();
Student studentToDelete = entityManager.find(Student.class, 1);
if (studentToDelete != null) {
entityManager.remove(studentToDelete);
entityManager.getTransaction().commit();
System.out.println("Student successfully deleted!");
} else {
System.out.println("Student not found!");
}
JPAUtil.close();
}
}
pom.xml:
<?xml version="1.0" encoding="UTF-8"?>
<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>org.example</groupId>
<artifactId>jpa-delete-entity-demo</artifactId>
<version>1.0-SNAPSHOT</version>
<name>jpa-delete-entity-demo</name>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.target>11</maven.compiler.target>
<maven.compiler.source>11</maven.compiler.source>
<junit.version>5.9.2</junit.version>
</properties>
<dependencies>
<dependency>
<groupId>org.hibernate.orm</groupId>
<artifactId>hibernate-core</artifactId>
<version>6.0.2.Final</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.28</version>
</dependency>
<dependency>
<groupId>org.glassfish.jaxb</groupId>
<artifactId>jaxb-runtime</artifactId>
<version>3.0.2</version>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
</plugins>
</build>
</project>
Step 7: Once the project is done, run the application and we can get the output like the below image.
output
In the above example, We can demonstrate the simple java application using the JPA and it can be delete the entity of the JPA application.
JPA – Deleting an Entity
In Java, JPA can be defined as Java Persistence API, deleting the entity is the crucial operation in managing database records. It can involve removing an object from the database and ensuring the data consistency and integrity of the application.
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