Interview Questions

Java Interview questions part 4

Part 1 | Part 2 | Part 3 | Part 4 | Part 5

Question - What is JDBC driver? 

Answer
The JDBC Driver provided by the JDBC API, is a vendor-specific implementations of the abstract classes. The driver is used to connect to the database.  

Question - What are the steps required to execute a query in JDBC?

Answer
Load JDBC drivers
Register the driver with DriverManager class
Open a connection
Create Statement object using connection object that enables to execute the query. 

Question - Define Connection pooling.  

Answer
A Connection pooling is a technique of reusing active database connections instead of creating a new connection with every request.

Question - What are the common tasks of JDBC?  

Answer
Create an instance of a JDBC driver 
Register a driver 
Specify a database 
Open a database connection
Submit a query
Receive results 
Process results 

Question - Describe the types of Beans. 

Answer
There are three types of Beans:  

Stateless Session Beans
Statefull Session Beans
Entity Beans

Stateless Session Beans
These beans do not maintain the state and the information are short lived.

Statefull Session Beans
These beans are also short lived and do not survive the server crashes. These beans are used to maintain the session of a client. 

Entity Beans
These beans store the data in a database.   

Question - Explain the Common use of EJB.   

Answer
The EJBs can be used to incorporate business logic in a web-centric application. 
The EJBs can be used to integrate business processes in Business-to-business (B2B) e-commerce applications.
In Enterprise Application Integration applications, EJBs can be used to house processing and mapping between different applications.  

Question - What are transaction isolation levels in EJB?   

Answer
Transaction_read_uncommitted
Transaction_read_committed
Transaction_repeatable_read
Transaction_serializable

Question - What is Entity Bean?   

Answer
The entity bean is used to represent data in the database. Entity beans provide a component model that allows developers to focus on business logic of the bean and other activities like managing persistence,transactions, and access control are taken care by the container.

There are two kinds of entity beans
Container-managed persistence
Bean-managed persistence    

Part 1 | Part 2 | Part 3 | Part 4 | Part 5