J2EE Interview Question and Answer

1. Explain J2ee component?

Ans. It is a software unit that is assembled into a J2ee application with related files and classes. E.g: Enterprise JavaBeans components are business components.

2. Name some types of modules defined by J2ee specification?

Ans.

• Application client
• Enterprise JavaBeans
• Web
• Resource adapter

3. What is the use of containers in J2EE?

Ans. It acts as a container between a component and a platform that provides the functionality supported by the component.

4. What are different types of containers?

Ans.

• Applet container
• Application client container
• Web container
• Enterprise JavaBeans container

5. Define J2ee module?

Ans. A collection of one or more J2ee components of the same container along with one descriptor of that type is known as J2ee module.

6. What are web components?

Ans. Java server pages technology and java servlet are web components.

7. What do you mean by JSF?

Ans. JSF stands for JavaServer Faces. It provides a set of reusable UI components for web applications.

8. What does MVC stand for?

Ans. MVC means model view controller. It is a software architectural pattern for implementing user interfaces on PCs.

9. Define Hashtable?

Ans. Hashtable is like a hashmap. It enables null values but not duplicate values.

10. What are the benefits of Hibernate?

Ans.

• Built-in connection pool implementation
• Standard ORM
• Mapping of domain object to relational database
• Layered architecture

11. Difference between public, private and protected?

Ans. Private: It has the data accessible to the class to which they belong

Protected: It has the data accessible to the class to which they belong and any subclass

Public: It has the data accessible to all the classes

12. What does web module have?

Ans.

• Class files for servlets
• Web development descriptor
• GIF and HTML files
• JSP files

13. What is HQL?

Ans. HQL (Hibernate query language) enables to the user to express queries in its own portable SQL extension.

14. What are the advantages of object relational mapping?

Ans.

• Code reuse
• Application maintainability
• Productivity
• Application design

15. What does .jar file contain?

Ans. The .jar file contains resources, libraries and accessory files like property files.

16. What are the JSP tags?

Ans. There are four different types of JSP tags:

• Declarations
• Scriplets
• Expressions
• Directives

17. Discuss the advantages of spring framework?

Ans.

• Easily testable components
• Lightweight container
• Easy initialization for properties
• Possibility to organize middle tier objects

18. What is URL?

Ans. URL (uniform resource locator) is the textual reference writing standard to an arbitrary piece of data in the World Wide Web.

19. What services are provided by EJB container?

Ans.

• Connection Pooling
• Component lifecycle management
• Security
• Transaction