Lapits Technologies Mean Stack Developer Interview Questions and Answers

finally is used to execute a block of code after try-catch block, while static block is executed when class is loaded.

• finally block is used to perform cleanup operations like closing database connections, file streams etc.

• static block is used to initialize static variables or perform any other static initialization.

• finally block is always executed whether an exception is thrown or not, while static block is executed on...read more

The @Autowired annotation in Spring is used to automatically wire dependencies into a bean.

• It eliminates the need for manual wiring of dependencies

• It can be used to inject dependencies into constructors, fields, and methods

• It can be used with other annotations like @Qualifier and @Value

• It can be used with both XML and Java-based configurations

To make a class immutable in Java, we need to follow certain guidelines.

• Make the class final

• Make all fields private and final

• Do not provide setter methods

• If the field is mutable, return a clone of it instead of the original object

• Ensure that any mutable objects passed to the constructor are not modified outside the class

Collections are data structures that store and manipulate groups of objects.

• Collections provide a way to manage and manipulate groups of objects

• Java provides several built-in collection classes such as ArrayList, LinkedList, HashSet, etc.

• Collections can be used to perform operations like searching, sorting, filtering, etc.

• Collections can store objects of any type, including primitive types and user-defined classes

ArrayList and Vector are similar but Vector is synchronized while HashMap and HashTable are both key-value pair data structures but HashTable is synchronized.

• ArrayList and Vector both implement List interface but Vector is thread-safe while ArrayList is not.

• Vector is slower than ArrayList due to synchronization.

• HashMap and HashTable both store key-value pairs but HashTable is thread-safe while HashMap is not.

• HashMap al...read more

Rest Api is a web service that uses HTTP methods to access and manipulate data.

• Rest stands for Representational State Transfer

• It is an architectural style for building web services

• Uses HTTP methods like GET, POST, PUT, DELETE

• Data is transferred in JSON or XML format

• Examples: Twitter API, Facebook Graph API

Program to add numbers in harmonic series (1+1/2+1/3+...+1/n)

• Create a variable to store the sum

• Use a loop to iterate through the series up to n

• Add each term to the sum

• Print the sum

An array linked list can be executed using a loop to traverse through the array and access the linked nodes.

• Create an array to store the linked nodes

• Assign the first node to the first element of the array

• Use a loop to traverse through the array and access the linked nodes

• To access the next node, use the index of the current node as the index of the next node in the array

• Stop the loop when the last node is reached

Character constants are fixed values represented by a single character in C++.

• They are enclosed in single quotes (' ')

• Examples include 'a', 'B', '5', '$'

• They are also known as character literals

OSI, TCP & IP are networking protocols used for communication between devices on a network.

• OSI (Open Systems Interconnection) is a conceptual model that defines how data is transmitted over a network.

• TCP (Transmission Control Protocol) is a protocol that ensures reliable transmission of data between devices.

• IP (Internet Protocol) is a protocol that handles the addressing and routing of data packets between devices on a...read more

Streams in C++ are used for input and output operations. Predefined streams in C++ include cin, cout, cerr, and clog.

• Streams in C++ are objects that allow reading from or writing to external sources or destinations.

• cin is the standard input stream used for reading input from the user.

• cout is the standard output stream used for printing output to the console.

• cerr is the standard error stream used for printing error mess...read more

RDBMS stands for Relational Database Management System.

• It is a type of database management system that stores data in tables with relationships between them.

• It uses SQL (Structured Query Language) to manipulate and retrieve data.

• Examples include MySQL, Oracle, and Microsoft SQL Server.

Normalisation is the process of organizing data in a database to reduce redundancy and improve data integrity.

• It involves breaking down a table into smaller tables and defining relationships between them.

• Normalization helps to eliminate data inconsistencies and anomalies.

• There are different levels of normalization, with each level having specific rules to follow.

• Examples of normalization include converting repeating gr...read more

INDEX is generally created on columns that are frequently used in WHERE, JOIN, and ORDER BY clauses.

• INDEX improves the performance of SELECT queries.

• INDEX should be created on columns with high selectivity.

• INDEX should not be created on columns with low selectivity.

• Examples of columns to create INDEX on are primary keys, foreign keys, and columns used in search queries.

Object oriented model is a programming paradigm that uses objects to represent real-world entities.

• Objects have properties and methods that define their behavior

• Encapsulation, inheritance, and polymorphism are key concepts in OOP

• Examples of OOP languages include Java, C++, and Python

Top-n analysis is a technique used in DBMS to retrieve the top n records based on a specific criteria.

• Used to retrieve top n records

• Based on specific criteria

• Commonly used in data analysis and reporting

DML is provided to manipulate data in a database.

• DML stands for Data Manipulation Language.

• It is used to insert, update, delete, and retrieve data from a database.

• DML commands include INSERT, UPDATE, DELETE, and SELECT.

• DML is essential for managing and maintaining data in a database.

Reference variables in C++ are aliases for other variables, allowing direct access and manipulation of the original data.

• Reference variables are declared using an ampersand (&) symbol.

• They must be initialized when declared and cannot be reassigned to refer to a different variable.

• Changes made to a reference variable affect the original variable it refers to.

• They are commonly used to pass variables by reference to funct...read more

RDBMS is a type of DBMS that stores data in a structured manner using tables with relationships.

• RDBMS stands for Relational Database Management System

• Data is stored in tables with predefined relationships

• Data is accessed using SQL (Structured Query Language)

• Examples include MySQL, Oracle, and SQL Server

• DBMS is a broader term that includes all types of database management systems

• Examples of DBMS include MongoDB, Cassand

Normalization is a process of organizing data in a database to eliminate redundancy and improve data integrity.

• First Normal Form (1NF) - Eliminate duplicate data by separating them into multiple tables.

• Second Normal Form (2NF) - Remove partial dependencies by creating separate tables for sets of attributes.

• Third Normal Form (3NF) - Eliminate transitive dependencies by creating separate tables for related attributes.

• Boy...read more

Scope rules in C++ determine the visibility and accessibility of variables and functions within a program.

• Variables declared within a block have local scope and are only accessible within that block.

• Global variables have file scope and can be accessed from any function within the file.

• Function parameters have function scope and are only accessible within that function.

• Nested blocks can have their own scope, and variabl...read more

BCNF is not necessarily better than 2NF & 3NF, it depends on the specific requirements of the database.

• BCNF is the highest normal form and ensures that there are no non-trivial functional dependencies between any subset of candidate keys.

• 2NF and 3NF are also important and should be used when appropriate.

• For example, if a database has a composite primary key and non-key attributes that depend on only one part of the key...read more

An operating system is a software that manages computer hardware and software resources.

• It acts as an interface between the user and the computer hardware.

• It provides services to applications and manages system resources.

• Examples include Windows, macOS, Linux, Android, and iOS.

Exclusive lock is used when a resource is being modified and prevents other processes from accessing it. Shared lock allows multiple processes to read a resource simultaneously.

• Exclusive lock is used for write operations, while shared lock is used for read operations.

• Exclusive lock blocks other processes from acquiring both exclusive and shared locks on the same resource.

• Shared lock allows multiple processes to acquire...read more

rand() generates a random number, srand() seeds the random number generator.

• rand() generates a pseudo-random number between 0 and RAND_MAX

• srand() sets the seed for the random number generator used by rand()

• srand() should be called before rand() to ensure different sequences of random numbers

• Example: srand(time(NULL)) sets the seed to the current time, ensuring a different sequence each time the program is run

A subquery is a query within another query used to retrieve data that will be used in the main query.

• Subqueries are enclosed in parentheses and placed within the WHERE clause of the main query.

• They can be used to filter results based on a condition that involves data from another table.

• Subqueries can also be used in the SELECT, FROM, and HAVING clauses.

• Examples include finding the average salary of employees in a depar...read more

Linked List is a linear data structure. Stack and Queue are abstract data types.

• Linked List: A collection of nodes where each node points to the next node.

• Stack: A data structure where elements are added and removed from the top only.

• Queue: A data structure where elements are added at the rear and removed from the front only.

• Example: Browser history can be implemented using a Linked List.

• Example: Undo/Redo functionalit...read more

Triggers are events that initiate an action or set of actions. They are commonly used in databases and automation systems.

• Triggers are used in databases to automatically execute a set of actions when a certain event occurs, such as inserting or updating data.

• They can also be used in automation systems to initiate a process or workflow when a specific event occurs, such as receiving an email or a file upload.

• Triggers ca...read more

Semaphore and monitor are synchronization tools used in concurrent programming.

• Semaphore is a signaling mechanism that allows multiple threads to access a shared resource simultaneously.

• Monitor is a synchronization construct that allows threads to have both mutual exclusion and the ability to wait (block) for a certain condition to become true.

• Semaphore is a lower-level primitive, while monitor is a higher-level abstra...read more

Transparent DBMS allows users to see and control the underlying database operations.

• Transparent DBMS provides visibility into the database operations and allows users to monitor and control them.

• It enables users to see how data is being stored, accessed, and manipulated in real-time.

• Examples include Oracle Transparent Data Encryption and Microsoft SQL Server Transparent Data Encryption.

• Transparent DBMS can improve secu...read more

RDBMS KERNEL is not a commonly used term in the industry.

• There is no widely accepted definition of RDBMS KERNEL.

• It may refer to the core components of a relational database management system.

• It could also be a term used by a specific company or product.

• Without more context, it is difficult to provide a specific answer.

Primary key uniquely identifies a record, foreign key links tables, candidate key can be primary key, super key is a set of attributes.

• Primary key: Unique identifier for a record in a table

• Foreign key: Links tables together by referencing the primary key of another table

• Candidate key: A set of attributes that can be used as a primary key

• Super key: A set of attributes that can uniquely identify a record

Dependency injection is a design pattern that allows objects to receive dependencies rather than creating them.

• It helps to decouple the code and makes it more testable and maintainable.

• It allows for easier swapping of dependencies without changing the code.

• There are three types of dependency injection: constructor injection, setter injection, and interface injection.

• Example: Instead of creating a database connection ob...read more

Bean factory is used for creating and managing instances of beans in Spring framework.

• Bean factory is responsible for creating and managing instances of beans defined in the Spring configuration file.

• It provides a way to decouple the configuration and specification of dependencies from the actual application code.

• Bean factory supports different scopes of beans such as singleton, prototype, request, session, etc.

• It also...read more