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JanJ2EE 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.
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.
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.
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?
Structs are based on MVC (Model-View-Controller) architecture used to design applications for large enterprises. It can be described in detail as follows –
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.
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.
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.
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
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.
Save () | Update () |
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. |
Load () | Get () |
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. |
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.
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.
To reduce the overall complexity of an enterprise application, the open source Spring Framework is used. The major benefits of any spring Framework include –
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?
A program that doesn’t have any complex operations like connection, business rules or database queries is termed as the thin client.
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.
Class Loading Phase, Instantiation Phase, Initialize Phase, Removal Phase, and the Request Handling Phase.
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