J2EE Interview Questions and Answers
J2EE or Java 2 Enterprise Edition is an open source platform to develop, deploy or manage the multi-tier or web-enabled apps. These applications are generally components-based and server-centric especially designed for the large enterprises. In this blog, we will focus on most popular J2EE interview questions and answers to tune your learning for basic J2EE concepts, theories or different coding techniques.
This blog is helpful for the learners planning to appear for J2EE interviews soon. With this complete guide, you can increase your chances of getting selected by top recruiters worldwide.
J2EE Interview Questions
- Name the major components for J2EE apps briefly?
- Name the different types of J2EE client?
- Define the struts in the J2EE framework?
- How to design interactive UI for J2EE apps?
- Define Hashtable and how it works in J2EE?
- Define Hibernate and HQL?
- Explain the limitation of Hibernate, if any?
- Explain the major benefits of Hibernate?
- Define the web components and how are they helpful?
- Define ORM and how it works in J2EE?
- How will you define save () or update () methods in Hibernate?
- How will you differentiate the get () and Load () methods?
- List the advantages of ORM (object-relational mapping)?
- Describe the web container in J2EE?
- Define the concept of connection pooling?
- What is Spring Framework and discuss its benefits?
- What are the different type of collections in hibernate?
- What is a thin client?
- Define the servlet?
- Name the different phases of servlet lifecycle?
J2EE Interview Questions & Answers
Once you will go through this blog, you would learn top J2EE interview questions and answers are frequently asked by the recruiters. These questions and answers are prepared after the careful research done by our experts and reviewed minutely by our Java development team. Let us switch to the questions answers for beginners and experienced one by one.
J2EE Interview Questions & Answers For Freshers
Q1). Name the major components for J2EE apps briefly?
The major components of any J2EE web-enabled app include – client-tier components, business tier components, web tier components, and EIS (Enterprise Information System) components etc.
- Client-tier components are made to run on client machine.
- Web tier components are made to run on J2EE server.
- Business tier components are made to run on J2EE server, and
- EIS components run over the EIS server.
Q2). Name the different types of J2EE client?
The different J2EE clients are Applets, application clients, wireless clients and Java Web start clients.
Read: What is Java Exponent? How to Do Exponents in Java?
Q3). Define the struts in the J2EE framework?
Structs are based on MVC (Model-View-Controller) architecture used to design applications for large enterprises. It can be described in detail as follows –
- Model – The internal state of a system is defined by Model. It may be either single or a cluster of Java Beans based on app architecture.
- View – The view of any enterprise app is usually designed by JSP technology.
- Controller – It is used to process the client request and respond accordingly based on the request. Basically, it is used to manage the actions of users.
Q4). How to design interactive UI for J2EE apps?
To design interactive User Interface in J2EE, you must opt for JSF (Java Server Faces). The framework has a wider set of reusable UI components that is based on MVC architecture and design concepts. Further, the automated data that is created at server side and displayed ay client side is also managed by the JSF.
Q5). Define Hashtable and how it works in J2EE?
Hashtable is taken as a cluster of synchronized objects where Null values are allowed but not the duplicated values. It works very much similar to the HashMap.
Q6). Define Hibernate and HQL?
Hibernate is an open-source query and object-relational mapping service. Here, you can write HQL (Hibernate Query Language) scripts instead of using SQL that saves a lot of time and efforts. Hibernate is closely related to composition, polymorphism, inheritance, and collections. With the help of this framework, you can process queries beautifully by using simple Java objects.
Q7). Explain the limitation of Hibernate, if any?
- The execution of queries is slower.
- There is only HQL support for composite keys.
- There are no shared references to the value type.
Q8). Explain the major benefits of Hibernate?
- Hibernate is independent of database and vendor so it is termed as the portable framework.
- Domain objects can be mapped to relational databases.
- JPA support for standard ORM.
- The database connectivity is better in Hibernate when compared to JDBC.
Q9). Define the web components and how are they helpful?
Java Servlets or Java Server Pages are the web components that dynamically receive requests from users and respond accordingly. JSP pages are further executed in the form of servlets to generate more static content for the web pages.
Read: Java.net Connectexception connection refused
Q10). Define ORM and how it works in J2EE?
ORM is abbreviated as Object-relational mapping in J2EE. The objects are mapped to tables in the relational databases by transforming data from one form to another.
J2EE Interview Questions & Answers For Experienced
Q11). How will you define save () or update () methods in Hibernate?
|It is used to save or store an object in the database. It creates a new entry every time you create a fresh object.
||It is used to update the existing objects once the record is found with the help of identifier.
Q12). How will you differentiate the get () and Load () methods?
|If an object is not found either in Cache or database, Load () method will throw an exception.
||If an object is not found in Cache or database, then Get () method returns a null value, not the exception.
Q13). List the advantages of ORM (object-relational mapping)?
- Productivity – The automatic code is generated that minimizes the overall data access time based on the data model defined.
- Performance – The complete data access needs of an application are managed by the automated code generated by the ORM. Because there is no need for any extra code so overall data access process is made faster and optimized.
- Vendor independent – The code generated is independent of the vendor that increased the overall portability of an application.
- Maintainability – The code is well tested generated by the ORM and only a developer can understand the code perfectly.
Q14). Describe the web container in J2EE?
There is an interface in between component and the low-level platform with defined functionality that is generally designed to support the component and termed as the container in J2EE.
Q15). Define the concept of connection pooling?
Connection Pooling is a simple concept that is popular to reuse the existing connections. In other words, if object connections are already well defined and connected then they can be reused whenever there is a requirement instead of generating the new one.
Q16). What is Spring Framework and discuss its benefits?
To reduce the overall complexity of an enterprise application, the open source Spring Framework is used. The major benefits of any spring Framework include –
- The middle tier objects can be managed more efficiently.
- The properties can be initialized quickly.
- The testability of application is made easier with injection dependencies.
- The containers are lightweight and components are defined clearly.
- The Spring services are managed or configured in runtime environment instead of focusing on its architectural layer.
Q17). What are the different type of collections in Hibernate?
A collection is defined as one-to-many references. The most popular collections in Hibernate include – Array, List, Set, Map, or Bag types.
Read: How to Call a Method in Java?
Q18). What is a thin client?
A program that doesn’t have any complex operations like connection, business rules or database queries is termed as the thin client.
Q19). Define the servlet?
Servlet is a server-side component that offers full functionalities to create a server-side program. The different servlets are available with a specific design for a variety of protocols. Most popular type of protocol for the servlet is HTTP.
Q20). Name the different phases of servlet lifecycle?
Class Loading Phase, Instantiation Phase, Initialize Phase, Removal Phase, and the Request Handling Phase.
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