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Top 20 J2EE Interview Questions and Answers

Published On: June 7, 2024

J2EE Interview Questions and Answers

Since J2EE is still the most widely used standard among Java developers, developers must understand J2EE concepts and have practical experience with them. The most frequently asked J2EE interview questions, for both novice and seasoned candidates, are listed in this article.

J2EE Interview Questions and Answers for Freshers

1. What is J2EE?

The term Java 2 Enterprise Edition is J2EE. Creating and implementing multi-tier web-based enterprise applications is what J2EE is all about. A collection of services, application programming interfaces (APIs), and protocols make up the J2EE platform. 

The J2EE platform adds the features needed to offer an enterprise-level Java platform that is full, stable, secure, and quick.

2. What distinguishes JVM Runtime, JVM Implementation, and JVM Specific?

The JVM standard is just the JVM specification. JVM implementation refers to how vendors implement it. A piece of software that is now running and supports Java-specific programming is called the JVM runtime.

3. Define JIT.

Java applications run faster thanks to the Just-in-Time compiler, which combines native machine code with platform-neutral bytecode during runtime.

4. What do JDK and JRE mean?

JDK is a kit that offers an environment for Java application development and execution. JRE, on the other hand, is a kit that offers an environment for the Java program to execute rather than develop.

5. Explain HQL.

An object-oriented query language is called Hibernate Query Language (HQL). HQL operates on persistent objects and properties, as opposed to SQL, which operates on tables and columns. HQL is the replacement for Java Persistence Query Language (JPQL). This implies that while all HQL searches are not JPQL queries, all JPQL inquiries are legitimate HQL queries.

6. Define a Java thin client

A thin client is not heavy. Through a regular socket connection, a thin client connects to the cluster without joining the cluster structure. A thin client is not utilized for computation and does not save any data. All operations are carried out via the standard node.

7. What is URN?

The acronym for Uniform Resource Name is URN. An entity’s distinctive identifier serves as its identity.

8. How does one apply spring?

Spring is an enterprise Java application development framework that is available as free software. It is among the most used Java frameworks. With Spring, developers can create reusable, tested, and highly performant code. 

9. Which components make up the multi-tier architecture?

The elements of a multi-tier architecture are the presentation tier, resource tier, and business tier.

10. Which are the various Spring modules?

The spring module list is 

  • Aspect-oriented programming
  • DAO module
  • O/R mapping module
  • Core container module
  • Web module
  • Application context module.

11. Explain JTA, JNDI, and JMS.

JNDI: Java Naming Directory Interface is known as JNDI. It facilitates directory service information access.

JMS: A Java Messaging Service is what it is. It is in charge of using different messaging platforms to deliver and receive messages.

JTA: A Java Transaction API is what it is. The transactions in an enterprise information system are coordinated and managed by it. 

12. What is a servlet?

A server-side element that offers server-side program development tools is called a servlet. It utilizes classes that are contained in a Java package.

13. What is build file in J2EE?

A build file is a tool for automating several tasks related to software development. In addition, the versions of libraries that need to be included are specified in the build file. Included are the many optimizations required for the project. Build provides a standardized approach to project building that scales with the project.

J2EE Interview Questions and Answers for Experienced

14. What is the EJB? In J2EE, how can you use it?

Enterprise Java Beans, or EJBs, are one of the most important parts of the J2EE platform. They allow the development and implementation of enterprise-level multi-tiered systems while maintaining resilience, scalability, and performance. 

When we want to use EJBs to do the following tasks:

Clustering: To provide high availability and fault tolerance when deploying an application in a cluster environment, EJBs can be used.

Concurrency without the use of threads: Concurrency is possible without the use of threads since EJBs are available in the EJB container and are instantiated via the object pool. This helps achieve performance without interacting with the complexity of threads. 

15. What is the Struts architecture model?

Strut is an application development framework that integrates messages, custom tags, Java Servlets, JSP, and other components to create enterprise-level applications. Its base is the Model-View-Controller (MVC) architecture.

View: Struts leverages JSP technology to provide views for applications at the enterprise level.

Model: This component defines the internal state of the system. The program may be designed as a single bean or as a Java Beans cluster, depending on its architecture.

Controller: It oversees user actions that respond to inquiries and process requests. A servlet is what it is. 

16. What features is a J2EE application supposed to have to function in a global economy?

A J2EE application needs to include the following components to function in a global economy:

Language Requirements: An application should support both regional and national languages to reach a larger user base.

Financial Consideration: Governments set and enforce taxes, tariffs, and limitations that differ from nation to nation. These components should all be considered while developing a J2EE application.

Legal Disparities: Every government has a unique collection of national laws, privacy laws, and customs. All relevant legislation must be followed by a newly created application. 

17. What do connectors do? Explain the architecture of the connectors.

By using common extension protocols, connectors provide connectivity to a range of enterprise information systems. 

A connector architecture consists of two components that are specific to business information systems: resource adapters and system-level contracts. The resource adapters are being plugged into the container. 

A resource adapter needs to meet the connector architecture’s requirements for resource management, security, transactions, and other areas before it can be connected to J2EE applications.

18. Describe action mapping

When using action mapping, the user designates the action class—that is, forwards on to which request-response is forwarded—for a certain URL, or path and distinct destination view. 

The information that the ActionServlet is aware of regarding the mapping of a certain request to an instance of a given Action class is defined by the ActionMapping. Access to this data is made direct by moving the mapping to the Action class’s execute() method.

19. Could you elaborate on CDATA?

CDATA, or “don’t interpret these characters,” is a predefined XML tag for character data. It is comparable to parsed character data (PCDATA), which is subject to the regular XML syntax standards. CDATA sections are used to display XML syntax examples.

20. What does the term “Component Contract” signify to you?

The component contract is the agreement between a J2EE component and its container. This kind of agreement consists of:

  • Life-cycle supervision of the element
  • An interface that an instance uses to access different services and information from its container
  • A list of services that each container’s constituent parts must receive. 

Conclusion

We hope these J2EE interview questions and answers will help you succeed in Java developer interviews. Kickstart your career by gaining expertise with our J2EE training in Chennai.

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