Introduction to Java EE Interview Questions And Answers
Java Enterprise Edition is a standard for developing applications based on enterprise software. Sun Microsystems and IBM at first premeditated Java EE to make simpler application development in a thin-client-tiered environment. Java EE reduces programming needs by generating components that are synchronized, reusable also allowing the tier to handle quite a few aspects of programming automatically.
While Java EE apps hosted at the server-side, familiar examples of Java EE clients are I device, standard web-based application, smartphone, RESTful web service, WebSocket or even microservices running in a Docker container.
API Specifications:
- Java APIs
- JSF Facelets Tag Library
- JSF JSP Tag Library
- Standard HTML Render Kit
- JSF JavaScript Documentation
So if you are looking for a job that is related to Java EE, you need to prepare for the 2021 Java EE Interview Questions. Though every Java EE interview is different and the scope of a job is also different, we can help you out with the top Java EE Interview Questions and Answers, which will help you take the leap and succeed in an interview.
Below is the 2021 Java EE Interview Questions that are mostly asked in an interview; these questions are divided into two parts:
Part 1 – Java EE Interview Questions (Basic)
This first part covers basic Java EE Interview Questions and Answers
Q1) Improvements to Java EE compared to J2EE?
Answer:
Java EE uses conventions in the place of configurations and also replaces XML files with Annotations. Components are defined as POJO. Also, to simplify the EJB’s dependency injections were introduced, and this also empowers POJO’s with enterprise features. The persistence layer was fully replaced by Java Persistence API’s. This is the most common Java EE Interview Questions asked in an interview.
Q2) Difference between Core Java, Java EE and Java ME?
Answer:
Java SE (Core Java): Java SE used for Developing a Standalone application, System Software that Runs in System only. In Java SE, you can gain knowledge of the Basic of Java Like Inheritance, Polymorphism, Strings etc.
Java EE (Advance Java): Java EE is used for developing Web Applications that Run with the assist of a Web Browser. In Java EE, you can gain knowledge of the Advance topics Like Servlet, Java Server Pages(JSP), Enterprise Java Beans(EJB) etc.
Java ME (Mobile Development with Java): Application that runs on the mobile phones are designed using Java ME.
Q3) Key Features of Java Enterprise edition?
Answer:
Availability: The Java EE system is made up to be up and ready at any given point in time. Several times the user demands could be too high. If a system cannot grip the given load, system downtime will be hit, and the company’s business performance will be hardly impacted. The is supposed to be supporting 24×7 services; hence the availability of an Enterprise System is critical.
Scalability: The way that businesses are handled and operated is changing. Enterprise Systems must have a flexible structural design, which can reply to fast changes that often happen in the organizations. These systems are highly scalable in order to adopt new changes happening in the organizations.
Performance: In order to improve business workflow, data control, as well as customer responsiveness, client management, all Organizations and Enterprises often invest heavily; the spending in Enterprise Systems enlarge and ultimately turns into a significant part of the total business cost.
Security: Security is one of the most important requirements in Enterprise Systems. The systems have to be secured in order to ensure continued system availability and data confidentiality.
Manageability: A huge proportion of Enterprise Systems be unsuccessful because of their elevated complexity, which leads to the statement that the systems are not easy to control and manage. In this case, the Enterprise Systems Management (ESM) specialists include supervising the operations of the system and the concert to track the source of problems and then identify and fix the problems in the fundamental layers.
Data Integrity: One of the primary design considerations for Enterprise Systems is data integrity. Data integrity means that data in the systems should not be lost or corrupted.
Interoperability: Interoperability is the ability of an Enterprise System (or any general IT system) to use information and functionality of another system. depicts data exchange between two systems.
Let us move to the next Java EE Interview Questions and Answers
Q4) Core Technologies of Java EE?
Answer:
Around 30 Java APIs included as Java EE core technologies, with that number approaching 50 with the eventual release of Java EE 8. These Java EE core technologies fall into the below-listed file categories:
- HTTP client technologies: For HTTP-based clients, Web Socket programming is included for Java EE, the JSF and Servlet APIs, an API for JSON processing and the JSP Standard Tag Library (JSTL).
- Resources and database access technologies: For external and back-end systems interactions, Java EE includes JavaMail, a Java Message Service (JMS)API, a standard connector architecture and a Java Transaction API (JTA) for enforcing two-phase commits.
- REST and web service technologies: To help with the development and deployment of REST-, SOAP-, XML- and JSON-based web services, the Java APIs for RESTful Web Services (JAX-RS) and XML-based web services (JAX-WS) are included, along with APIs for XML messaging and XML Registries (JAXR).
- Java EE security and container management: implementation of security and management of Java EE containers, Java Authorization Contract are accessible for developers and the Java Authentication Service Provider Interface for Containers.
Q5) List the components of Java EE applications?
Answer:
- Client-tier components: Executes on the client machine.
- Web tier components: Resides and executes on the Java EE server.
- Business tier components: Runs on the Java EE server.
- Enterprise information system software (EIS software): Runs on the EIS server.
Part 2 –Java EE Interview Questions (Advanced)
Let us now have a look at the advanced Java EE Interview Questions.
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Q6) What are the Java EE client types?
Answer:
- Applets
- Application clients
- Java Web Start enabled clients by Java Web Start technology.
- Wireless clients, based on the Mobile Information Device Profile (MIDP) technology.
Q7) Strategies do you consider to import and export XML content?
Answer:
As per the schema, JAXB is used to serialize and deserialize objects into XML. In the absence of schema, two situations arise.
- Considering XML content: SAX is used to recommend serial access for the whole document or accessed randomly using DOM.
- If simply parts of XML content is considered, then XPath can be used, or StAX in case operations must be executed instantaneously following every needed part is established in the document.
Let us move to the next Java EE Interview Questions and Answers
Q8) Can you list some differences between a relational model and an object model?
Answer:
A relation can be established between an object model and a relational model. yet several differences exist within then
| Relational Model | Object Model |
| A foreign key has the same type as the target’s primary key | They attribute points to the entire related object |
| An intermediary entity is needed to generate N-N relations | Here N-N relations can be easily generated |
| No support for inheritance, interfaces, and polymorphism. | Supports inheritance, interface, polymorphism |
Q9) Illustrate the use of Stateless Session Bean, State full Session Bean, and Singleton Session Bean?
Answer:
Stateless Session Beans: They are used when there is no need to conserve the state of objects between business transactions. All transaction holds its own instances and instances of components can be retrieved from pools of objects. It is not compulsory for large cases; quite a few operations are performed inside a transaction for maintaining database consistency.
State full Session Beans: These are used when there is the need to conserve the state of objects between business transactions. Every instance of the component has its own objects. Diverse transactions customize these objects, and they are leftover after reaching a predefined time of inactivity. They allow to cache the data intensively, such as long record sets for pagination and referring the data, in order to reduce the volume of IO operations with the database.
A singleton session bean: Exists for the lifecycle of the application and Instantiated once per application. This kind of component can be used, for example, to initialize the application at its start-up and share a specific object across the application.
Q10) What is the Spring Framework, and discuss its benefits?
Answer:
To reduce the overall complexity of an enterprise application, the open-source Spring Framework is used. This is the most popular Java EE Interview Questions asked in an interview. The major benefits of any spring Framework include
- The middle tier objects can be managed more efficiently.
- The properties can be initialized quickly.
- Injection dependencies make application testing much easier phenomena.
- The containers are lightweight, and components are defined clearly.
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