The Ultimate Guide to Preparing for Jakarta EE Interview Questions

Jakarta EE has become one of the most popular enterprise application development platforms. With its robust APIs and runtime environment, Jakarta EE empowers developers to build scalable, reliable and secure server-side applications.

However, mastering Jakarta EE requires considerable knowledge and experience. Jakarta EE interview questions assess your understanding of the platform’s core concepts and test your ability to apply that knowledge to real-world scenarios.

In this comprehensive guide we will explore the most common Jakarta EE interview questions provide sample answers. and offer tips to help you thoroughly prepare for your next technical interview

Why Learn Jakarta EE?

Before diving into specific questions, it’s worth briefly understanding why Jakarta EE is widely used and what value it offers.

Jakarta EE extends the Java SE platform with APIs and services for developing enterprise applications. This includes technologies for web services, distributed computing, database access, messaging, transactions, and more.

Compared to alternatives like .NET or Ruby on Rails, key advantages of Jakarta EE include:

• Productivity – Robust frameworks like EJB and JSF reduce boilerplate code. Developers can focus on business logic.
• Portability – Applications run on any Jakarta EE compliant application server. No vendor lock-in.
• Scalability and Reliability – Clustering, load balancing, failover built into application servers.
• Security – Declarative security model with container-managed authentication and authorization.
• Community – Backed by Eclipse Foundation with wide industry support. Mature platform with many resources available.

Now let’s explore some common interview questions on Jakarta EE.

Core Jakarta EE Interview Questions

These fundamental questions test your understanding of Jakarta EE’s architecture and components:

Q1. What is the difference between Java EE and Jakarta EE?

Java EE was the original specification for enterprise Java released under Oracle’s stewardship. Jakarta EE is the new branding after Oracle donated Java EE technologies to Eclipse Foundation.

While Java EE development has ceased, Jakarta EE continues to evolve with a vendor-neutral, community-driven approach. It’s essentially the future of enterprise Java.

Q2. Explain the Jakarta EE architecture.

Jakarta EE follows a multi-tier distributed architecture. Key tiers include:

• Client tier – Generates requests, handles user interactions and displays results. E.g. browser, mobile app.
• Web tier – Processes requests, applies business logic, provides web UI. Handles presentation and control logic.
• Business tier – Implements business logic and handles transactions. EJBs are used here.
• Enterprise Information System (EIS) tier – Stores enterprise data and provides backend services. Includes databases, legacy systems, etc.

The tiers communicate via well-defined APIs and protocols like HTTP, JDBC, JMS, etc. This modular approach allows flexibility in enhancing or replacing a specific tier.

Q3. What are some important APIs in Jakarta EE?

Key Jakarta EE APIs include:

• Jakarta Servlet – For developing web applications and REST APIs.
• Jakarta Server Pages (JSP) – Scripting language for dynamic web content.
• Jakarta Server Faces (JSF) – MVC framework for building web UIs.
• Enterprise JavaBeans (EJB) – For creating distributed, transactional components.
• Jakarta Persistence API (JPA) – Abstraction for ORM with databases.
• Jakarta Messaging (JMS) – API for service-oriented asynchronous messaging.
• Jakarta RESTful Web Services (JAX-RS) – Developing REST services.
• Jakarta WebSocket – Full-duplex communication channels over TCP.

Q4. What is CDI and why is it important in Jakarta EE?

CDI (Context and Dependency Injection) provides a robust dependency injection mechanism in Jakarta EE. It manages the creation and lifecycle of components like EJBs and Managed Beans.

Key benefits of CDI:

• Promotes loose coupling between components.
• Integrates Jakarta EE technologies like JSF, JPA, EJB seamlessly.
• Enables scoping of beans to appropriate contexts like request, session, application etc.
• Implementation agnostic. Components depend on interfaces rather than concrete classes.

By relying on CDI for wiring dependencies, components become highly modular and testable.

Q5. Explain different scopes in CDI.

The scope defines the lifecycle and visibility of a CDI bean. Jakarta EE defines several scopes:

• @ApplicationScoped – Single instance per application.
• @SessionScoped – Instance per user session.
• @RequestScoped – Instance per request.
• @Dependent – Object graph determines scope.
• @Singleton – Single instance per application.
• @ConversationScoped – Instance across multiple requests in conversation.

Using the appropriate scope prevents creating unnecessary instances and enables bean reuse where applicable.

Jakarta EE Web Technologies

Web development is a major use case for Jakarta EE. Expect questions on Jakarta Servlets, JSP, JSF, and REST APIs.

Q6. How do servlets handle multiple requests?

Servlets are inherently not thread-safe. The servlet container handles multiple requests using multithreading as follows:

• The container creates a pool with a limited number of threads.
• Each request is handled by a separate worker thread from the pool.
• The servlet instance is shared among multiple threads but only one thread accesses it at a time.
• Synchronization mechanisms like synchronized blocks must be used for shared resources.

Q7. What are some disadvantages of using JSPs over servlets?

Some downsides of JSPs compared to servlets:

• Performance – JSPs need to be compiled into servlets first, adding processing overhead. Servlets are precompiled.
• Separation of concerns – Difficult to separate business logic from presentation in JSPs. Better with servlets + JSP.
• Testing – JSPs cannot be unit tested. Servlets are better suited for testing.
• Readability – Embedded Java code can make complex JSPs hard to understand.
• IDE support – Better IDE support for servlet coding than visual JSP designers.

So for complex applications, it is better to limit JSPs to presentation and use servlets for controller logic.

Q8. What are the main components of JSF framework?

JSF follows the MVC pattern and provides the following components:

• Models – Managed beans representing application data and logic.
• Views – JSPs containing JSF UI components like h:inputText, h:dataTable etc.
• Controllers – Managed beans handling navigation and application flow.
• Backing beans – Beans connecting views to models.
• Navigation rules – Defines navigation between pages.
• EL (Expression Language) – Access backend data and invoke methods.
• JSF lifecycle – Handles request processing and response rendering.

Together these components allow building server-side MVC-based web applications.

Q9. How does Jakarta RESTful web services framework help build REST APIs?

The Jakarta RESTful web services API (JAX-RS) offers a standardized way to develop REST services in Java. Key features:

• Resource classes – POJOs annotated with @Path to specify URL patterns.
• HTTP method annotations – @GET, @POST, @PUT, @DELETE on methods.
• Automatic serialization – Java objects to/from JSON or XML.
• URIBuilder – Construct URIs by appending path segments.
• Exception mapping – Map exceptions to HTTP error codes.
• Filters and interceptors – Intercept and pre/post process requests.

JAX-RS handles a lot of low-level details so developers can focus on business logic.

Jakarta Enterprise Beans

Enterprise JavaBeans (EJBs) form the core of Jakarta EE business logic. You should be well-versed in different types of enterprise beans.

Q10. What are the different types of enterprise beans?

The main types of enterprise beans are:

• Session bean – Implements business logic, similar to a session with a client. Further divided into:
  • Stateless – Does not hold state between requests.
  • Stateful – Maintains state across multiple client interactions.
  • Singleton – Single shared instance.
• Message-driven bean – Asynchronous message consumer from JMS.
• Entity bean – Persistent data model mapped to database tables via ORM.

Q11. When would you use a stateless session bean?

Stateless session beans are ideal for reusable business logic that does not depend on any conversational state. Key traits: