100+ Lead Software Engineer Interview Questions and Answers

Spring Boot dependency injection is a design pattern where objects are passed their dependencies rather than creating them internally.

• In Spring Boot, dependency injection is achieved through the use of @Autowired annotation.

• It helps in achieving loose coupling between classes and promotes easier testing and maintenance.

• Example: @Autowired private UserService userService; // Injecting UserService dependency

Yes, I have extensive experience in Java programming.

• Proficient in Java programming language

• Experience with Java frameworks like Spring and Hibernate

• Developed various applications using Java

• Familiar with Java design patterns and best practices

I always strive to be truthful and honest in all situations.

• I believe in honesty and integrity in all aspects of my life.

• Being truthful builds trust and credibility with colleagues and clients.

• Lying can lead to negative consequences and damage relationships.

• Example: I always provide accurate status updates on projects, even if it means admitting mistakes or delays.

Prototype to remove duplicate words from a sentence using an array of strings

• Create a function that takes in a sentence as input

• Split the sentence into an array of words

• Use a Set data structure to store unique words

• Iterate through the array of words and add each word to the Set

• Convert the Set back to an array to get the unique words

• Join the unique words back into a sentence

Find the maximum 3-digit number from an array of both negative and positive numbers.

• Iterate through the array and keep track of the 3 largest positive numbers.

• Iterate through the array and keep track of the 3 smallest negative numbers.

• Compare the largest positive numbers with the smallest negative numbers to find the maximum 3-digit number.

The 3 hat problem involves guessing the color of your own hat based on the colors of hats worn by others.

• Each person can see the colors of the hats of the people in front of them, but not their own hat color.

• By analyzing the guesses and hat colors of others, one can deduce their own hat color.

• Communication and logical reasoning are key to solving this puzzle.

The program uses the Observer design pattern.

• The Observer pattern is used to define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.

• It promotes loose coupling between objects, allowing for easier maintenance and scalability.

• Examples of Observer pattern implementation can be seen in event handling systems, such as in GUI frameworks like Java Swing.

Rate limiter is used to control the rate of incoming requests to a server or API.

• Prevents server overload by limiting the number of requests a client can make in a specific time period

• Helps protect against DDoS attacks by limiting the rate of incoming requests

• Ensures fair usage of resources by preventing one client from monopolizing server resources

• Can be implemented using algorithms like token bucket or leaky bucket

• Example: Setting a rate limit of 100 requests per minute for...read more

Jenkins is a continuous integration tool used for automating software development processes, while Kubernetes is a container orchestration platform for managing containerized applications.

• Jenkins is used for automating the building, testing, and deployment of software projects.

• Kubernetes helps in automating the deployment, scaling, and management of containerized applications.

• Jenkins can be integrated with Kubernetes to automate the deployment of applications in containers.

• Bo...read more

I have a strong grip on Java due to my extensive experience in developing enterprise applications.

• Extensive experience in developing enterprise applications using Java

• Proficient in Java frameworks like Spring and Hibernate

• Strong understanding of object-oriented programming principles

• Comfortable with multi-threading and concurrency in Java

• Familiar with Java 8 features like lambda expressions and streams

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

• Dependency injection helps to decouple components and make them more modular.

• It allows for easier testing and maintenance of code.

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

• Example: Instead of creating a database connection object within a class, the object is passed in as a dependency.

• Ex...read more

App performance should consider factors like code optimization, network efficiency, memory management, and user experience.

• Optimizing code for efficiency and speed

• Minimizing network requests and optimizing data transfer

• Efficient memory management to prevent crashes and slowdowns

• Prioritizing user experience for smooth navigation and responsiveness

Fail-fast iterators throw ConcurrentModificationException if the collection is modified while iterating. Fail-safe iterators do not throw exceptions.

• Fail-fast iterators fail immediately if the collection is modified during iteration.

• Fail-safe iterators do not throw exceptions if the collection is modified during iteration.

• Fail-fast iterators are used in Java collections like ArrayList, HashMap.

• Fail-safe iterators are used in Java collections like CopyOnWriteArrayList, Concurr...read more

To get the 3rd last node of a linked list, we can use two pointers approach.

• Start two pointers at the head of the linked list

• Move the first pointer to the 3rd node from the beginning

• Then move both pointers one node at a time until the first pointer reaches the end

I am proficient in Java, Python, and JavaScript.

• Java

• Python

• JavaScript

Lazy loading is a technique used to defer the loading of non-critical resources until they are actually needed.

• It improves page load time and performance.

• It reduces the initial load time of a web page.

• It is commonly used for images, videos, and other media files.

• It can be implemented using JavaScript or server-side scripting.

• Example: Images below the fold on a webpage are loaded only when the user scrolls down to them.

SQL query to find 2nd highest salary.

• Use ORDER BY to sort the salaries in descending order

• Use LIMIT to get the second highest salary

• Use subquery to avoid duplicates if multiple employees have the same salary

Program to print odd and even numbers using multithreading

• Create two separate threads for printing odd and even numbers

• Use synchronization mechanisms like mutex or semaphore to ensure proper ordering of output

• Example: Thread 1 prints odd numbers (1, 3, 5, ...) and Thread 2 prints even numbers (2, 4, 6, ...)

Abstract interface is used to define a set of methods without implementation. Difference lies in their usage.

• Abstract interface is used to define a contract between two parties.

• It is used to provide a common set of methods that can be implemented by different classes.

• It is used to achieve abstraction and loose coupling.

• Abstract classes can have implementation while interfaces cannot.

• Abstract classes can have constructors while interfaces cannot.

• Example: Comparable interface i...read more

Java performance and query optimization in Oracle

• Use prepared statements to avoid SQL injection and improve performance

• Use indexes to speed up query execution

• Avoid using SELECT * and only select necessary columns

• Use connection pooling to reuse database connections

• Use caching to reduce database round trips

• Tune database parameters like buffer cache and shared pool size

• Use profiling tools to identify performance bottlenecks

Javascript task to get and iterate over a list of string values

• Use Array data structure to store the list of string values

• Use for loop or forEach method to iterate over the list

• Access each value using its index or value itself

Springboot provides various testing tools for microservices

• SpringBootTest for integration testing

• MockMvc for testing REST endpoints

• MockBean for mocking dependencies

• TestRestTemplate for testing REST endpoints

• WireMock for testing external services

• JUnit and Mockito for unit testing

• Use Docker for testing in a containerized environment

Our current application architecture follows a microservices design pattern with a combination of front-end and back-end services.

• Utilizes Docker containers for easy deployment and scalability

• Uses RESTful APIs for communication between services

• Front-end built with React.js and back-end services in Node.js

• Data storage handled by MongoDB for flexibility and scalability

Memory management in Java is handled automatically by the JVM through garbage collection.

• Java uses automatic memory management through garbage collection to allocate and deallocate memory.

• Garbage collection in Java helps in reclaiming memory occupied by objects that are no longer in use.

• Java provides the 'finalize()' method to perform cleanup operations before an object is garbage collected.

Twitter can use cloud storage services like AWS S3 for effective image storage.

• Twitter can use a CDN to distribute images globally.

• Images can be compressed and optimized for faster loading.

• Twitter can implement lazy loading to improve page speed.

• Users can be given the option to upload images directly to cloud storage services like AWS S3.

• Twitter can use image recognition technology to automatically tag and categorize images.

Object-oriented programming is a programming paradigm that uses objects to represent and manipulate data.

• Encapsulation: bundling data and methods together in a class

• Inheritance: creating new classes from existing ones

• Polymorphism: using a single interface to represent different types

• Abstraction: simplifying complex systems by breaking them into smaller, manageable parts

Motivation to change can come from personal growth, career advancement, new challenges, or a desire for innovation.

• Personal growth and development

• Career advancement opportunities

• Facing new challenges

• Desire for innovation and improvement

Microservice architecture with Spring Boot is a popular approach to building scalable and resilient applications.

• Spring Boot provides a convenient way to create and deploy microservices

• Each microservice should have a clear and well-defined responsibility

• Communication between microservices can be achieved through REST APIs or messaging systems like Kafka

• Containerization with Docker and orchestration with Kubernetes can simplify deployment and scaling

• Monitoring and logging are ...read more

Thinking outside the box involves exploring unconventional solutions to complex problems.

• Encourage brainstorming sessions to generate diverse ideas

• Challenge assumptions and traditional approaches

• Experiment with different perspectives and viewpoints

• Utilize analogies and metaphors to spark creativity

• Seek inspiration from unrelated fields or industries

Ajax calls are asynchronous HTTP requests made by JavaScript to a server without reloading the page.

• Ajax stands for Asynchronous JavaScript and XML

• Used to update parts of a web page without reloading the entire page

• Can be used to fetch data from a server and display it on a web page

• Examples: Google Maps, Facebook News Feed

Code review involves checking for code quality, functionality, security, and adherence to coding standards.

• Checking for code quality and readability

• Ensuring the code functions as intended

• Identifying and fixing security vulnerabilities

• Verifying adherence to coding standards and best practices

• Providing constructive feedback to the developer

OOPS concept is based on four main principles: Encapsulation, Inheritance, Polymorphism, and Abstraction.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Inheritance: Allowing a new class to inherit properties and behavior from an existing class.

• Polymorphism: Ability to present the same interface for different data types.

• Abstraction: Hiding the complex implementation details and showing only the necessary features.

OOPS stands for Object-Oriented Programming. Inheritance is a feature that allows a class to inherit properties and behavior from another class.

• OOPS is a programming paradigm that uses objects to design applications.

• Inheritance allows a class to inherit attributes and methods from another class.

• It promotes code reusability and helps in creating a hierarchical relationship between classes.

• Example: Class 'Animal' can be a base class with properties like 'name' and methods like ...read more

Code programs to solve basic string manipulations

• Use built-in string functions like substring, replace, and split

• Implement algorithms for reversing a string, checking for palindromes, and counting occurrences of a character

• Handle edge cases like empty strings and null inputs

Design a parking lot system at a low level

• Divide system into components like parking spots, ticketing system, payment system

• Implement data structures like queues for managing parking spots

• Use algorithms like least recently used for spot allocation

• Consider scalability and performance in design

Logging and tracing are essential for debugging and monitoring distributed applications.

• Use a centralized logging system to collect logs from all nodes in the distributed system.

• Include unique identifiers in log messages to enable tracing of requests across multiple nodes.

• Use log aggregation tools like ELK stack or Splunk to analyze and visualize logs.

• Consider using distributed tracing tools like Jaeger or Zipkin to trace requests across multiple services.

• Ensure that log mess...read more

Use a custom comparator function to sort the deck of cards based on their rank and suit.

• Create a custom comparator function that compares the rank and suit of two cards.

• Use the custom comparator function to sort the deck of cards.

• Example: ['2H', '3D', 'AS', ...]

Code quality can be improved by following coding standards, code reviews, automated testing, refactoring, and continuous integration.

• Follow coding standards to ensure consistency and readability

• Conduct regular code reviews to catch errors and improve design

• Implement automated testing to catch bugs early in the development process

• Refactor code to improve maintainability and reduce technical debt

• Use continuous integration to regularly build and test code changes

LRU cache is a data structure that stores the most recently used items, discarding the least recently used items when full.

• Use a LinkedHashMap to store key-value pairs with access order

• Override removeEldestEntry method to limit the size of the cache

• Update the access order of items when they are accessed

To find the middle element in a linked list, use the slow and fast pointer approach.

• Initialize two pointers, slow and fast, both pointing to the head of the linked list.

• Move the slow pointer by one step and the fast pointer by two steps until the fast pointer reaches the end of the list.

• The element pointed to by the slow pointer at this point is the middle element of the linked list.

To call an SQL procedure from code, use the appropriate syntax and connection to the database.

• Use the appropriate SQL command to call the procedure (e.g. EXEC or CALL).

• Ensure you have a connection to the database established in your code.

• Pass any required parameters to the procedure when calling it.

• Handle any return values or output parameters as needed.

Collection framework is a unified architecture for representing and manipulating collections of objects in Java.

• It provides interfaces (like List, Set, Map) and classes (like ArrayList, HashSet, HashMap) to store and manipulate groups of objects.

• It allows for easy manipulation, sorting, searching, and iteration of collections.

• Collections in the framework can store objects of any type, including user-defined classes.

• Example: List names = new ArrayList<>(); names.add("Alice"); ...read more

thread.join() is used to wait for a thread to finish its execution before moving on to the next steps.

• thread.join() blocks the current thread until the thread it is called on completes its execution.

• It is commonly used in multi-threaded applications to ensure that all threads have finished before proceeding.

• Without thread.join(), the main thread may continue executing while other threads are still running.

• Example: thread1.join() will wait for thread1 to finish before continui...read more

Find all triplets in an array of integers without duplicates

• Iterate through the array and for each element, find all pairs that sum up to the negative of that element

• Use a set to store the seen elements to avoid duplicates

• Time complexity can be improved to O(n^2) by sorting the array first

Microservices architecture with containerization using Docker and Kubernetes

• Utilizes microservices architecture for scalability and flexibility

• Each microservice is containerized using Docker for easy deployment and management

• Orchestrated using Kubernetes for automated scaling and load balancing

Design a fare splitting app for easy division of expenses among friends.

• Allow users to input expenses and split them among friends

• Implement features for adding friends, creating groups, and tracking balances

• Include options for equal split, custom split, and adjustments

• Generate reports for each user's share and overall expenses

• Consider security measures for payment integration

• Design user-friendly interface for seamless experience