Interview Questions on Servlet, JSP, Hibernate For Fresher’s

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October 29, 2021
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1)What is JSP?

JSP is java server Pages used for creating dynamic web Application. JSP is a platform independent way of creating dynamic web Application. Using JSP you can create Simple to Complex dynamic webapplications. JSP is a integral part of J2EE.

2)What is Hibernate?

Hibernate is a framework which simplifies the database applications. It is a Open source , Light weight framework, ORM (Object Relational Mapping)tool, Hibernate is mainly used for database applications. You can use Hibernate instead of JDBC(java Database Connectivity).

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3)What is JPA?

JPA is Java Persistence API (application programming Interface) for data persistence.JPA provides some features and ORM(Object Relational Mapping) Tools. To Map a Plain old Java Objects into a table.

4)What is ORM Tool?

ORM(Object Relational Mapping) this is a tool that makes develop job much simpler by creating automatic table, As a name suggest it Maps Object to storage.

5) what is Package for JPA?

javax.persistence package that contains JPA Classes and Interfaces for creating applications using hibernate.

6) what are the advantages of Hibernate?

Here are Some of advantages of Hibernate.

1)Hibernate is Open Source and Lightweight

2)Fast Performance

3)Data Base Independent Query

4) Self Table creation.

7) What are the Layers of Hibernate Architecture?

Database Layer
Java Program Layer
Hibernate framework Layer
Back end Layer
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8)What are the Objects Used By Hibernate?

Hibernate framework uses many objects Like

Java API, JDBC,Java Transaction API,JNDI java Naming Directory API.

9) what is session Factory?

The Package or API org.hibernate.SessionFactory interface provides sessionFactory to get the session object.It is a an interface.

10)what is transaction?

Transaction is an Object it specifies automatic unit of work. IT provodes the method for transaction management.

IT is available in org.hibernate.Transaction

11) Explain the Session Object?

Session object is a interface between java application and database. IT is a wrapper around java data base connectivity (JDBC). org.hibernate.Session interface provides the methods for save, update, delete, operation , For crud operation. It also includes the method for Transaction, query, criteria.

12) What is a connection Provider?

Connection Provider is a factory of Java Database Connectivity(JDBC).It is a abstraction Layer for Driver Manager or Data Source.

13) What are the steps for creating Hibernate Application?

For creating the hibernate Application we need to have a fallowing steps

Create a Plain Old Java Objects (POJO).
Create a Configuration file.
Create a Persists class. OR Mapping Class.
Load Jar files of hibernate OR Use Maven.
Create a Class to store data,
Last You run application .

Hibernate will automatically creates a table from POJO class and Map it to table.

14) what is a Mapping File name?What are the elements of mapping file?

Hibernate.cfg.xml is a Mapping File name. IT is a XML file it will map to a table.

It Contains Many elements Like.

Hibernate-mapping : IT is a root element. It contains all mapping elements.

Class : Here class a persists class. It is a POJO (Plain Old Java Objects)class.

Id: IT is a primary key in a class. It is Compulsory for Mapping.

Property : IT specifies property for a class.

Hibernate File Looks Like Here

<?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>

<property name=“hibernate.connection.driver_class”>com.mysql.jdbc.Driver</property>

<property name=“hibernate.connection.url”>jdbc:mysql://localhost:3306/hibernatedemo</property>

<property name=“hbm2ddl.auto”>create</property>

<property name=“hibernate.dialect”>org.hibernate.dialect.MySQLInnoDBDialect</property>

</session-factory>

</hibernate-configuration>

15) How to Store data in a table Using Hibernate . Write Down the Steps ?

Here is a Code for Storing the data.

import javax.transaction.HeuristicMixedException;

import javax.transaction.HeuristicRollbackException;

import javax.transaction.RollbackException;

import javax.transaction.SystemException;

import javax.transaction.Transaction;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.boot.MetadataSources;

import org.hibernate.boot.registry.StandardServiceRegistry;

import org.hibernate.boot.registry.StandardServiceRegistryBuilder;

import org.osgi.service.blueprint.reflect.Metadata;

public class MainEntry

{

public static void main(String[] args)

{

// TODO Auto-generated method stub

StandardServiceRegistry ssr = new StandardServiceRegistryBuilder().configure(“hibernate.cfg.xml”).build();

Metadata meta = (Metadata) new MetadataSources(ssr).getMetadataBuilder().build();

SessionFactory factory = ((org.hibernate.boot.Metadata) meta).getSessionFactoryBuilder().build();

Session session = factory.openSession();

Transaction t = (Transaction) session.beginTransaction();

Student e1=new Student();

e1.setId(101);

e1.setName(“student”);

e1.setCourse(“java”);

session.save(e1);

try {

t.commit();

} catch (SecurityException | RollbackException | HeuristicMixedException | HeuristicRollbackException

| SystemException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

System.out.println(“successfully saved”);

factory.close();

session.close();

}

16) What is a persistence class?

Persistence class a plain old java object. It contains getters and setters.

Code for Persistence class.

import javax.persistence.Entity;

import javax.persistence.Id;

@Entity

public class Employee

{

@Id

private int eid;

private String ename, dept, skill;

public int getEid() {

return eid;

}

public void setEid(int eid) {

this.eid = eid;

}

public String getEname() {

return ename;

}

public void setEname(String ename) {

this.ename = ename;

}

public String getDept() {

return dept;

}

public void setDept(String dept) {

this.dept = dept;

}

public String getSkill() {

return skill;

}

public void setSkill(String skill) {

this.skill = skill;

}

17) How to add mapping file in a configuration file.

We add above code in hibernate.cfg.xml file.

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18) What are the annotation used in hibernate application.

Annotation are meta keywords and only compilers will understands with the help of Java Training in Pune. Hibernate application can be created using Annotations. Like

@Id => it is Used for creating primary key.

@Entity => It is used for mapping class file to entity

@table => it is used to naming a table .

@column => It is used for making property as a column.

All hibernate Annotations are available in javax.persistence. Hibernate Entity Manager implements all the interfaces and Life cycle defined in JPA specification.

19) Explain SQL Dialects In Hibernate?

The dialects specifies the databases like. Which database it will work like mysql, oracle, etc.

Based on Dialect Hibernate generate the SQL. So it defined in hibernate.cfg.xml file.

<property name=“hibernate.dialect”>org.hibernate.dialect.MySQLInnoDBDialect</property>

All Dialects are avaible in org.hibernate.dialect. Package.

20) What are Generators classes in hibernate?

Generator class is used for unique id for objects. Generator classes are defined in hibernate framework. All generator classes are exists in org.hibernate.id.IdentifierGenerator Package.

Hibernate Framework provides built in classes. These are mentioned here

Increment,assigned,sequence,identity,uuid, guid,foreign.sequence-identity.

21) How To map inheritance Mapping in hibernate?

There are three inheritance mapping in hibernate like

Table Per Hiearchy,Table Per concrete Class,Table Per sub class.

22) Which annotation is used for One-to-one Mapping?

@OneToOne(targetEntity=Address.class,cascade=CascadeType.ALL)

@OneToOne(targetEntity=Employee.class)

23) what is pom.xml file in maven?

In Maven pom.xml file is project object Model that is used for adding dependency files that require for creating the application .

Here is a dependency for mysql, and dependency for hibernate

<groupId>org.hibernate</groupId>

<artifactId>hibernate-core</artifactId>

<version>5.4.16.Final</version>

</dependency>

<!– https://mvnrepository.com/artifact/mysql/mysql-connector-java –>

<groupId>mysql</groupId>

<artifactId>mysql-connector-java</artifactId>

</dependency>

24)Explain Bidirectional Association in hibernate.

It helps to fetch data from dependent object.if Java Course in Pune apply one-to-one, one to many mapping relationship for mapping classes and files is called Bidirectional Association.

For example we can fetch data from both tables like dependent and independent tables.

25)Explain Lazy Collection in hibernate.

In Lazy collections hibernate loads the child objects on demand. So Application performance gets improved. In hibernate 3.0 by default lazy collections is enabled.

Lazy Collection is by default True.

26) Explain caching in hibernate?

Caching improves the performances of a application by pooling object into cache. Cache is useful when we need to fetch the same data repeatedly.

In hibernate there are two Types of caching

First level cache

Second level cache.

In first level cache session object stores first level cache. Session object holds first level cache. By default it is enabled.

Second level cache Java Classes in Pune need to enable it explicitly. So cache is available for entire application.

Session Factory object holds second level cache.

27) Explain Core Interfaces of Hibernate.

The core interfaces in hibernate are-

Configuration
Session Factory
Session
Query
Criteria
Transaction

The core interfaces are also called key components in hibernate.

28) How to create SQL in hibernate?

Session.CreateSQLQuery() method is used for SQL in hibernate.

29) What is HQL?

Hibernate Query Language is called HQL . That is used like a sql. If anybody from development background which have very less knowledge about sql can use HQL. HQL interacts with a class .

Persists class it will map.

Here are few advantages of HQL

if you have very less knowledge about sql . you can go for HQL. No need to learn SQL to work with a database.
HQL is database independent.
HQL is very simple way to write.

29) What are different kinds of mapping in hibernate?

One to one mapping, one to many mapping, many to one mapping, many to many mapping.

30) What are the states of objects in hibernate?

There are 3 states of object in hibernate . Transient, Persistent, Detached.

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31) what is session.persist()?.

Syntax of session. persist() method.

public void persist(Object o)

it returns the void it returns nothing.

32) What are the advantages of ORM?

Application development is fast.
Generates key automatically.
Automatic mapping to a class.
No need to have a knowledge of SQL.

33) What is difference between update() and merge() method ?

Update will update the table . it will edit the table.

Merge will combine the tables.

Update is used inside a session only. Once session is closed it will throw exception.

For merge no need to of session object.

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Interview Questions on Servlet, JSP, Hibernate For Fresher’s

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