10+ PolicyX.com Interview Questions and Answers

To restrict a class from being inherited, mark it as final.

• Use the final keyword before the class declaration.

• Final classes cannot be subclassed.

• Any attempt to subclass a final class will result in a compile-time error.

Constructors are special methods used to initialize objects. Overloading allows multiple constructors with different parameters.

• Constructors have the same name as the class and no return type.

• Overloading constructors allows for different ways to initialize objects.

• Example: public class Person { public Person(string name) { } public Person(string name, int age) { } }

• Overloaded constructors can call each other using the 'this' keyword.

Use bubble sort algorithm to rearrange the array in decreasing order.

• Iterate through the array and compare adjacent elements, swapping them if they are in the wrong order.

• Repeat this process until the array is sorted in decreasing order.

• Example: ['apple', 'banana', 'cherry'] -> ['cherry', 'banana', 'apple']

Encapsulation is the concept of bundling data and methods that operate on the data into a single unit.

• Encapsulation helps in hiding the internal state of an object and restricting access to it.

• It allows for better control over the data by preventing direct access from outside the class.

• Example: In object-oriented programming, classes are used to implement encapsulation by combining data attributes and methods.

• TDP stands for Transmission Control Protocol, a connection-oriented...read more

I have worked with React, Node.js, and AWS recently.

• Developed a web application using React and Node.js

• Deployed the application on AWS EC2 instance

• Used AWS S3 for storing and retrieving files

• Implemented authentication and authorization using AWS Cognito

• Integrated Stripe payment gateway for online payments

Constraints in SQL are rules that limit the type of data that can be inserted, updated or deleted from a table.

• Constraints ensure data integrity and consistency.

• Types of constraints include primary key, foreign key, unique, check, and default constraints.

• Examples of constraints include ensuring a column cannot have null values, or ensuring a foreign key references a valid primary key.

• Constraints can be added when creating a table or altered later using the ALTER TABLE stateme...read more

Procedure and package are two types of database objects used in Oracle database.

• A procedure is a subprogram that performs a specific action and can be called by other programs.

• A package is a collection of related procedures, functions, and variables that can be used by multiple programs.

• Procedures and packages are stored in the database and can be called from any program that has access to the database.

• Procedures and packages can be used to encapsulate business logic and impr...read more

View is a virtual table while Materialized view is a physical table.

• View is a logical representation of data while Materialized view is a physical copy of data.

• View is updated dynamically while Materialized view needs to be refreshed manually.

• Materialized view is faster for read-heavy operations while View is better for write-heavy operations.

• Materialized view can be indexed while View cannot be indexed.

Selection sort is a simple sorting algorithm that repeatedly selects the smallest element from an unsorted list.

• It has a time complexity of O(n^2)

• It is an in-place comparison-based algorithm

• It is not suitable for large datasets

• Example: [64, 25, 12, 22, 11] -> [11, 12, 22, 25, 64]

ETL design involves identifying data sources, defining data transformations, and selecting a target system for loading the transformed data.

• Identify data sources and determine the data to be extracted

• Define data transformations to convert the extracted data into the desired format

• Select a target system for loading the transformed data

• Consider scalability, performance, and data quality issues

• Use ETL tools such as Informatica, Talend, or SSIS to automate the process

• Test and val...read more

Reverse a string by iterating through the characters and swapping them

• Create a function that takes a string as input

• Initialize two pointers, one at the beginning and one at the end of the string

• Swap the characters at the two pointers and move them towards the center until they meet