10+ Fullstack Java Developer Interview Questions and Answers for Freshers

The dot (.) accesses class properties, while the hash (#) denotes private fields in JavaScript classes.

• Dot notation (.) is used to access public properties and methods of a class instance.

• Example: class Person { name; constructor(name) { this.name = name; } } const p = new Person('Alice'); console.log(p.name); // Alice

• Hash notation (#) is used to define private fields in a class, which are not accessible outside the class.

• Example: class Person { #age; constructor(age) { this....read more

Use a messaging system to share information from receptionist to doctor

• Implement a messaging system using a message broker like RabbitMQ or Apache Kafka

• Create a message queue for receptionist to send messages to the doctor

• Doctor subscribes to the message queue to receive messages from receptionist

• Messages can contain patient information, appointment details, etc.

Effective cloud deployment management involves architecture design, CI/CD pipelines, and monitoring for scalability and reliability.

• Define architecture using microservices for scalability and maintainability.

• Utilize cloud services like AWS, Azure, or Google Cloud for hosting.

• Implement CI/CD pipelines using tools like Jenkins or GitHub Actions for automated deployments.

• Use containerization (e.g., Docker) to ensure consistency across environments.

• Incorporate monitoring and logg...read more

Languages commonly used in web development include HTML, CSS, and JavaScript.

• HTML is used for creating the structure of web pages

• CSS is used for styling the web pages

• JavaScript is used for adding interactivity to web pages

Containerization simplifies deployment by packaging applications with their dependencies, ensuring consistency across environments.

• Use Docker to create container images that encapsulate your application and its dependencies.

• Leverage Docker Compose for multi-container applications, allowing you to define services in a single YAML file.

• Utilize Kubernetes for orchestration, managing container deployment, scaling, and networking.

• Implement CI/CD pipelines with tools like Jenkins o...read more

Developing REST APIs and microservices involves designing, implementing, and deploying scalable web services using Java technologies.

• Use Spring Boot to create RESTful services quickly with minimal configuration.

• Define endpoints using @RestController and @RequestMapping annotations.

• Utilize JPA/Hibernate for database interactions and entity management.

• Implement security using Spring Security for authentication and authorization.

• Use Docker to containerize microservices for easy ...read more

Quick sort is an efficient sorting algorithm that uses a divide-and-conquer approach to sort elements in an array.

• Quick sort selects a 'pivot' element and partitions the array into two sub-arrays: elements less than the pivot and elements greater than it.

• The process is recursively applied to the sub-arrays until the base case of an array with one or zero elements is reached.

• Example: For the array [3, 6, 8, 10, 1, 2, 1], choosing 6 as the pivot results in [3, 1, 2, 1] and [8, ...read more

Design a schema for a social media platform

• Create tables for users, posts, comments, and likes

• Include foreign keys to link tables together

• Add columns for user information such as name, email, and password

• Include timestamps for when posts and comments were created

• Consider adding a table for hashtags to allow for easy searching

Garbage collector is a program that automatically frees up memory occupied by objects that are no longer in use.

• Garbage collector is a part of Java Virtual Machine (JVM)

• It runs in the background and periodically checks for objects that are no longer in use

• It frees up memory occupied by those objects, making it available for new objects

• Garbage collector helps in preventing memory leaks and improves performance

• Example: If an object is created in a method and the method ends, th...read more

Binary search is a search algorithm that finds the position of a target value within a sorted array.

• It works by repeatedly dividing the search space in half.

• Compare the target value with the middle element of the array.

• If the target value is smaller, search the left half of the array.

• If the target value is larger, search the right half of the array.

• Continue dividing and searching until the target value is found or the search space is empty.

A variable is a named storage location in a computer's memory that can hold a value.

• Variables are used to store and manipulate data in a program.

• They have a name, a data type, and a value.

• The value of a variable can be changed during program execution.

• Variables can be used to perform calculations, store user input, or hold intermediate results.

• Examples: int age = 25; String name = "John"; double salary = 5000.50;

An algorithm is a step-by-step procedure or set of rules for solving a problem or accomplishing a task.

• An algorithm is a well-defined computational procedure.

• It consists of a sequence of steps that can be executed in a finite amount of time.

• Algorithms can be represented using pseudocode or flowcharts.

• They are used in various fields like computer science, mathematics, and engineering.

• Examples of algorithms include sorting algorithms (e.g., bubble sort, merge sort) and searchin...read more

Multithreading is a programming technique that allows concurrent execution of two or more threads for improved performance.

• Multithreading enables parallel execution, improving application responsiveness.

• Each thread runs independently, sharing the same memory space, which can lead to resource contention.

• Java provides built-in support for multithreading through the Thread class and Runnable interface.

• Example: A web server handling multiple client requests simultaneously using s...read more

An object is an instance of a class that encapsulates data and behavior. A class is a blueprint for creating objects.

• An object is a real-world entity with its own state and behavior.

• A class is a template or blueprint that defines the properties and methods of an object.

• Objects are created from classes using the 'new' keyword.

• Classes can be used to create multiple objects with similar characteristics.

• Objects can interact with each other by invoking methods and accessing proper...read more

Fibonacci series is a sequence of numbers where each number is the sum of the two preceding ones.

• The series starts with 0 and 1.

• Each subsequent number is the sum of the two previous numbers.

• The formula to calculate the nth Fibonacci number is F(n) = F(n-1) + F(n-2).

• Example: 0, 1, 1, 2, 3, 5, 8, 13, 21, ...