Introduction to J2EE Interview Questions And Answers
So you have finally found your dream job in J2EE but are wondering how to crack the 2021 J2EE Interview and what the probable J2EE Interview Questions could be. Every interview is different, and the scope of a job is different too. Keeping this in mind, we have designed the most common J2EE Interview Questions and Answers to help you get success in your interview.
Below are the top J2EE Interview Questions that are asked frequently in an interview; these Top interview questions are divided into parts which are as follows:
Part 1 – J2EE Interview Questions (Basic)
This first part covers basic J2EE interview questions and answers.
1. What is J2EE? Name its components and client types.
Answer:
J2EE stands for Java 2 Enterprise edition. Its functionality includes the development of multiple-tier web-based applications. This platform consists of a set of services, protocols, and APIs.
Components are:
- Client tier components: These are the ones that execute on the client machine
- Web tier components: These get executed on the J2EE server.
- Business tier components: They get executed on the J2EE server
- Enterprise-level system software: They get executed on the EIS server.
J2EE Client types:
- Application clients
- Applets
- Java web-enabled clients who use Java web start technology
- Wireless clients who are based upon Mobile information device Profile popularly known as MIDP technology
2. What is MVC on struts?
Answer:
The MVC, popularly known as Model-View-Controller, can be described in detail.
- Model: The model is used to represent the internal workings of the system as a single entity or as a multi-Java bean entity
- View: Often, Java views are constructed using JSP (Java Server Pages) technology.
- Controller: This is the processor that focuses on client request receiving and delivering a new user interface set as per the request. The primary component in the framework is the “ActionServlet” servlet class.
Let us move on to the following J2EE Interview Questions.
3. What is ORM and its benefits of it?
Answer:
These are the basic J2EE Interview Questions asked in an interview. ORM stands for object-relational mapping. The objects in a java class are mapped with relational database tables using metadata to describe the mapping between database and objects. It transforms the data from one object to another. The benefits include:
- Maintainability: This ensures that all the code generated from ORM is well tested, and correcting the functionality is only something the developer can do.
- Productivity: It ends up reducing the time for data-level access coding using automatic code creation, which is based on a defined data model tools
- Performance: The code generated from the ORM is used to manage the application’s data access needs. We do not need to create any data access code; the one present is optimized to speed up the data access process.
- Vendor independence: The code generated from ORM is independent of the vendor. This is done to increase the portability of the application.
4. Explain important methods such as save(), Saveorupdate(), load(), get()?
Answer:
The save() method is used in hibernate, which is used to store the object in the database. The check for duplicate records is also put before it is inserted.
On the other hand, save or update() is used to update the object using an identifier. Once the identifier value is NULL, the method save() can be directly called.
When the object is unavailable in both cache and database, the load() throws an exception. It returns no null value.
When the object is unavailable in either database or cache, get() is used, which returns a null value.
5. What is Spring? Explain its advantages and the benefits of the spring framework.
Answer:
Spring is an open-source Java-based application that aims to reduce enterprise application development’s complexity. It is based on inversion controlling or dependency injection design patterns.
The advantages of using Spring for application development are as follows:
- Creation of POJOs (Plain Old Java Objects) is done, which then facilitates development to reuse existing components.
- It is possible to reduce the development cost by improving application development productivity.
- Dependency injection improves the testability of the application.
- It is used to improve maintainability with reduced code coupling.
- The need to have an application server is minimized and works on enterprise services.
Benefits of using the Spring framework:
- Spring framework allows for organizing middle-tier objects in a much more efficient way.
- Properties initialization is easy.
- Easy testing of components
- Lightweight container
- Spring framework provides the possibility of configuring management services in any runtime environment in any architectural layer.
Part 2 – J2EE Interview Questions (Advanced)
Let us now have a look at the advanced J2EE Interview Questions.
6. Describe the Servlet?
Answer:
Servlets are the server-side components that are used to provide a powerful mechanism for creating server-side programs. The servlets are available in a design for many protocols. Servlet is also platform-independent and server independent. The most commonly used protocol in the servlet is HTTP. A servlet is also a pure Java object.
7. What are the different phases of the Servlet life cycle?
Answer:
The different phases of the servlet life cycle are:
- Class loading phase: web container is used to load the servlet class files (*.class)
- Instantiation phase: The default no-arg constructor is called, and the servlet class gets instantiated.
- Initialization phase: The method init() is called in this phase only once in a servlet’s lifetime. Servlet configuration is generally assigned to the servlet.
- Request handling phase: This is the phase where the servlets spend maximum time. Servlets provide the services to various requests by calling service ().
- Removal phase: Destroy function is used to invoke the servlet destruction. Garbage collection occurs later.
Let us move on to the following J2EE Interview Questions.
8. What are the different types of JSP tags?
Answer:
There are four different types of JSP tags:
- Directives
- Declaration
- Expressions
- Scripts
9. Explain the basic and subtypes of EJBs?
Answer:
These are the advanced J2EE Interview Questions asked in an interview. Two main types and subtypes of EJBs are:
—Session Beans:
- Stateful session beans
- Stateless session beans
–Entity Beans:
- Bean-managed persistence
- Container-Managed Persistence
- Message-driven beans
10. What is the JSP directive?
Answer:
It is a mechanism to provide metadata information to a web container about a JSP file. Different types of JSP directives are:
- Page directive
- Include directive
- Taglib directive
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