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J2EE Interview Questions and Answers

1) What is J2EE?

J2EE means Java 2 Enterprise Edition. The functionality of J2EE is developing multitier web-based applications .The J2EE platform is consists of a set of services, application programming interfaces (APIs), and protocols.

2) What are the four components of J2EE application?

  • Application clients components.
  • Servlet and JSP technology are web components.
  • Business components (JavaBeans).
  • Resource adapter components

3) What are types of J2EE clients?

  • Applets
  • Application clients
  • Java Web Start-enabled clients, by Java Web Start technology.
  • Wireless clients, based on MIDP technology.

4) What are considered as a web component? 

Java Servlet and Java Server Pages technology components are web components. Servlets are Java programming language that dynamically receive requests and make responses. JSP pages execute as servlets but allow a more natural approach to creating static content.

5) What is JSF?

JavaServer Faces (JSF) is a user interface (UI) designing framework for Java web applications. JSF provide a set of reusable UI components, standard for web applications.JSF is based on MVC design pattern. It automatically saves the form data to server and populates the form date when display at client side.

6) Define Hash table

HashTable is just like Hash Map,Collection having key(Unique),value pairs. Hashtable is a collection Synchronozed object .It does not allow duplicate values but it allows null values.

7) What is Hibernate?

Hibernate is a open source object-relational mapping and query service. In hibernate we can write HQL instead of SQL which save developers to spend more time on writing the native SQL. Hibernate has more powerful association, inheritance, polymorphism, composition, and collections. It is a beautiful approach for persisting into database using the java objects. Hibernate also allows you to express queries using java-based criteria .

8 ) What is the limitation of hibernate?

  •  Slower in executing the queries than queries are used directly.
  • Only query language support for composite keys.
  • No shared references to value types.

9) What are the advantage of hibernate.

  •  Hibernate is portable i mean database independent, Vendor independence.
  •  Standard ORM also supports JPA
  •  Mapping of Domain object to relational database.
  •  Hibernate is better then plain JDBC.
  •  JPA provider in JPA based applications.

10) What is ORM?

ORM stands for Object-Relational mapping. The objects in a Java class which is mapped in to the tables of a relational database using the metadata that describes the mapping between the objects and the database. It works by transforming the data from one representation to another.