NEC Java Developer Interview Questions and Answers

Oops concepts in Java

• Encapsulation - hiding implementation details

• Inheritance - reusing code and creating parent-child relationships

• Polymorphism - multiple forms of a method or object

• Abstraction - creating abstract classes and interfaces

• Example: Encapsulation - using private variables and public methods

• Example: Inheritance - creating a subclass that inherits from a superclass

• Example: Polymorphism - using method overloa...read more

Altering columns in databases involves modifying the structure of a table by adding, deleting or modifying columns.

• Use ALTER TABLE statement to modify columns

• Add new columns using ADD COLUMN

• Delete columns using DROP COLUMN

• Modify columns using MODIFY COLUMN

• Changing column data type may result in data loss

Reversing a number in Java

• Convert the number to a string

• Use StringBuilder to reverse the string

• Convert the reversed string back to a number

To extract words from a line in Java, split the line using whitespace as delimiter.

• Use the split() method of String class

• Pass the whitespace regex as argument to split() method

• Iterate over the resulting array to get individual words

I am a software developer with experience in multiple programming languages and a passion for problem-solving.

• Experienced in Java, C++, and Python

• Strong knowledge of data structures and algorithms

• Proficient in web development using HTML, CSS, and JavaScript

• Familiar with agile development methodologies

• Excellent problem-solving and analytical skills

Automation framework is a set of guidelines, standards, and coding practices used to create automated test scripts.

• It provides a structured way to develop and maintain automated tests

• It includes tools, libraries, and reusable components

• It helps in reducing the time and effort required for testing

• Examples include Selenium, Appium, and Robot Framework

High severity refers to critical defects that impact the core functionality of the software, while low severity refers to minor issues that have minimal impact on functionality.

• High severity issues can cause the software to crash or result in data loss.

• Low severity issues are cosmetic or minor usability problems.

• From a QA point of view, high severity issues are more critical as they can significantly impact the user ex...read more

Class is a blueprint for creating objects while interface defines a contract for classes to implement.

• A class can have attributes and methods while an interface only has method signatures.

• A class can be instantiated while an interface cannot.

• A class can only inherit from one class while it can implement multiple interfaces.

• Example: Class - Animal, Interface - Flyable

• Animal can have attributes like name, age, etc. and m...read more

Static keyword is used to declare a variable or method that belongs to the class rather than an instance of the class.

• Static variables are shared among all instances of a class

• Static methods can be called without creating an instance of the class

• Static blocks are used to initialize static variables

• Static keyword can also be used to create nested classes

• Example: public static int count;

Access modifiers control the visibility and accessibility of class members.

• Public: accessible from anywhere

• Private: accessible only within the class

• Protected: accessible within the class and its subclasses

• Default: accessible within the same package

• Used to enforce encapsulation and prevent unauthorized access

Interface defines only method signatures while abstract class can have both method signatures and implementations.

• An interface can be implemented by multiple classes while an abstract class can only be extended by one class.

• An abstract class can have constructors while an interface cannot.

• An abstract class can have instance variables while an interface cannot.

• An abstract class can provide default implementations for so...read more

A program for login scenario using defined automation architecture.

• Identify the elements on the login page such as username, password, and login button

• Use automation tools like Selenium to interact with the elements and input data

• Verify successful login by checking for expected elements on the landing page

• Implement error handling for incorrect login credentials

• Use a modular and scalable architecture for maintainability

To store and print numbers from an array using arrayList.

• Create an arrayList object

• Loop through the array and add each element to the arrayList using add() method

• Print the arrayList using toString() method

• Example: int[] arr = {1, 2, 3}; ArrayList list = new ArrayList<>(); for(int num : arr) { list.add(num); } System.out.println(list.toString());

Test scenario for download functionality of a songs website

• Verify that the download button is visible and clickable

• Check that the downloaded file is in the correct format

• Ensure that the downloaded file is not corrupted

• Test the download speed for different file sizes

• Verify that the download progress is displayed to the user

Cache stores data temporarily to reduce server load while cookies store user information for website personalization.

• Cache stores frequently accessed data to reduce server load and improve website performance.

• Cookies store user information such as login credentials, preferences, and shopping cart items.

• Cache is temporary and can be cleared at any time, while cookies can have an expiration date.

• Cache is stored on the us...read more