Java Interview Questions for 2 to 5 yrs - Java Developer

Hello All,
This blog lists the interview questions that you are likely to face in an Interview if you are Java developer between 2 to 5 years.
When you reach experience level of more than 2 years it is assumed by the interviewer that you have good hand on experience in Java stack.
Sometimes the interviews are for a specific project. Like a project may require candidate to have experience in Spring or Struts or Hibernate. Or sometimes the interview is not for a specific project and is for a open requirement.

Sometimes specific skills are looked for, like the candidate should have experience in SOAP and REST Web-services.

The interviewer is not expecting the candidate to know the designing or high level architecture of the project. What he is expecting is the candidate should be aware of the Project, the technologies used and should be aware of the role he played in the project. As this is not a fresher interview the questions would start with basics and then go in deep.

Below here are the list of questions.

How to create a Software application

There has been lot of discussion on how a Software application should be developd.

What should be the Architecture?
What can be the best framework?
What should be the design?
What design principles can be applied?
How to cater to always changing requirements?
How to for-see a requirement?
Which database to use?

Different types of Computer Viruses

                                              Different types of Computer Viruses

A computer virus is often defined as a program which specifically designed in order to cause harm to the computer. Computer viruses are transmitted and affect the computer via portable devices, files that are being downloaded using the internet, malicious scripts and many more. A virus gets associated with the host file and infects the computer, each and every time the user clicks on the particular infected file. Few viruses can replicate themselves and can actually cause further harmful damages to the computer. Here is a list of different types of Computer Viruses and what do they do.

Macro Viruses
Macro Viruses generally affect files that were created by using certain applications and programs which contain macro files, for example pps, xls, doc and mdb. These macro files automatically get infected along with the templates and documents associated with the files. These viruses tend to hide in documents those that are shared via e-mails and other networks. Relax, bablas, Melissa.A and 097M/Y2K Aare name of Macro Viruses that can affect files and documents stored in a computer, quite harmfully.

Java Developer 4 to 6 yrs exp Interview at Cognizant

Following were the questions which are asked to my colleagues at experience of 4 to 6 years.

1.  Tell me about your current project ?
2.  What were your roles and responsibilities in your project?
3.  Can you draw architecture diagram of your project?

Java 8 New Features

Java 8 comes with very exciting features of functional programming with lambda expression and streams.

Lets take a look at it features

Lambda Looping

Lambda expression can be used for looping over a Collection.

Custom Java HashMap - Internal Working

HashMap is a Collection class in Java that stores objects with the help of hascode and equals. It is said to be faster in retrieving objects.
Lets create a custom implementation of HashMap  and understand how it works. To understand HashMap you need to first understand Singly and DoublyLinkedList.

HashMap stores objects in form of Key and Value. A value can be fetched by passing the Key.

HashMap stores objects into different buckets(LinkedList). The object with same hashcode are stored in same LinkedList. Remember that the objects are stored in key-value pairs. The hashcode of key is used and not the hashcode of value. Only Key alone is required to put and get the object. Value is just a object placed against the key, So depending upon how many objects(Keys) are present with different hashcodes, that many LinkedList gets created.

Symmetric Key Encryption between JAVA and IOS

There has been a exponential increase in REST services implementation between IOS/Android devices and Java Middleware, This has become the solution architecture for most applications which provide support on IOS/Android devices and also provide interface on web using java web application.

To make the communication secure it is necessary that this REST messages are made secure. This can be achieved using symmetric encryption mechanism.

Node JS Express Mongo

This blog will help you to create a NodeJS application with the help of express, jade and mongo DB


1. Install Node JS
Go to link http://nodejs.org/ and click the Install button. It will identify your workstations operating system and start download an msi file.
After the file is downloaded install it at you preferred location.

Java Singleton Pattern

Singleton pattern is the most common types of patterns used in Java. It is also very common that interviewers ask questions to explain and implement singleton pattern

Lets first define Singleton
Singleton is a class whose only one object can be created.
There are couple of ways to implement Singleton class. Lets see the simplest one first.