40+ Lead Developer Interview Questions and Answers

OAuth2 is a protocol for authentication and authorization that allows third-party applications to access user data without sharing passwords.

• OAuth2 provides a secure and standardized way for users to grant access to their resources to third-party applications.

• It involves the exchange of tokens between the user, the third-party application, and the resource server.

• Authentication is handled by the authorization server, which verifies the user's identity and issues an access tok...read more

Design patterns in Java are reusable solutions to common software design problems.

• Design patterns should be used when there is a recurring problem in software design.

• Design patterns can improve code readability, maintainability, and scalability.

• Examples of design patterns include Singleton, Factory, Observer, and Decorator.

• It's important to choose the right design pattern for the specific problem at hand.

• Design patterns should not be overused and should be balanced with simpl...read more

JWT is a token format while OAuth2 is a protocol. Both can be used to secure REST endpoints.

• JWT is a self-contained token that contains user information and can be used for authentication and authorization.

• OAuth2 is a protocol that allows third-party applications to access user data without sharing passwords.

• To secure REST endpoints, both JWT and OAuth2 can be used depending on the use case.

• For example, JWT can be used for stateless authentication while OAuth2 can be used for...read more

Java 8 streams are functional programming constructs that allow for efficient processing of large data sets.

• Streams are composed of a source, intermediate operations, and a terminal operation.

• Intermediate operations include filter, map, and sorted, and are lazily evaluated.

• Terminal operations trigger the evaluation of the stream and include forEach, reduce, and collect.

• Streams can be parallelized for even greater performance.

• Streams are designed to work with lambdas and funct...read more

Traversal conditions for a Doubly Linked List involve moving forward and backward through each node.

• Start at the head node and move to the next node by following the 'next' pointer.

• To traverse backward, start at the tail node and move to the previous node by following the 'prev' pointer.

• Continue this process until reaching the end of the list.

Fixed thread pool has a fixed number of threads while cached thread pool creates new threads as needed.

• Fixed thread pool is suitable for tasks with a known number of threads

• Cached thread pool is suitable for tasks with unknown number of threads

• Fixed thread pool can cause resource wastage if the number of threads is too high

• Cached thread pool can cause performance issues if the number of threads is too high

• Example: Fixed thread pool can be used for a web server with a fixed nu...read more

Using cache with Spring Boot

• Add @EnableCaching annotation to main class

• Add @Cacheable annotation to methods that need caching

• Configure cache properties in application.properties file

• Use CacheManager to manage caches

• Example: @Cacheable(value = "users", key = "#id")

Filter is a method used to extract specific data from a larger set based on certain criteria.

• Filter is required to extract specific data from a larger set.

• It is used to reduce the amount of data that needs to be processed.

• Filter can be applied to arrays, objects, and even strings.

• Examples include filtering out all even numbers from an array or all emails from a list that contain a specific keyword.

Spring MVC follows the Model-View-Controller (MVC) pattern for building web applications.

• Model represents the data and business logic

• View renders the model data and provides user interface

• Controller handles user requests, updates model and selects view

• Spring MVC provides DispatcherServlet as front controller

• RequestMapping annotation maps URL to controller method

• ModelAndView object returns model data and view name

Spring app config can be handled using various methods such as XML configuration, Java configuration, and annotation-based configuration.

• XML configuration involves creating an XML file and defining beans and their dependencies.

• Java configuration involves creating a Java class and using annotations to define beans and their dependencies.

• Annotation-based configuration involves using annotations to define beans and their dependencies.

• Spring Boot provides a convenient way to hand...read more

Improving application performance requires optimizing code, database queries, and server resources.

• Identify and fix slow database queries

• Use caching to reduce server load

• Optimize code by reducing unnecessary loops and improving algorithms

• Use a content delivery network (CDN) to reduce server load

• Upgrade server hardware or use cloud-based resources

• Minimize HTTP requests and reduce file sizes for faster page load times

Salesforce CPQ data can be migrated from external system to Salesforce using Data Loader or third-party tools.

• Export data from external system in CSV format

• Map fields in CSV file to Salesforce CPQ fields

• Use Data Loader or third-party tools to import data into Salesforce

• Validate data after import to ensure accuracy

Microservices use various communication patterns like synchronous, asynchronous, event-driven, and message-based.

• Synchronous communication involves direct request-response interactions between services.

• Asynchronous communication uses messaging systems like RabbitMQ or Kafka to decouple services.

• Event-driven communication involves services publishing events to a message broker, which other services can subscribe to.

• Message-based communication uses a shared message broker to se...read more

Program to check prime number and reverse a string

• For checking prime number, iterate from 2 to n/2 and check if n is divisible by any number

• For reversing a string, use a loop to iterate through the characters and build the reversed string

Design patterns in Laravel are reusable solutions to common problems in software design.

• Design patterns help in organizing code and improving code reusability.

• Some common design patterns in Laravel include Singleton, Factory, Repository, and Observer.

• Singleton pattern ensures that only one instance of a class is created.

• Factory pattern is used to create objects without specifying the exact class of object that will be created.

• Repository pattern provides a separation between t...read more

Filters in MVC are used to intercept and modify incoming requests or outgoing responses.

• Filters can be used to implement authentication and authorization.

• They can be used to handle exception and error logging.

• Filters can be used to modify the response before it is sent to the client.

• They can be used to implement caching and performance optimizations.

• Filters can be applied globally or to specific controllers or actions.

Manager groups are a way to group managers together for sharing records and managing access.

• Manager groups are created by administrators to group managers together based on their role or function.

• They are used to share records and manage access to those records.

• Manager groups can be used in sharing rules, manual sharing, and Apex managed sharing.

• For example, a manager group could be created for all sales managers to share leads and opportunities with each other.

Custom exception handling is the process of creating and handling exceptions specific to an application or system.

• Custom exceptions are created by extending the base Exception class in the programming language.

• They allow for more specific error messages and handling based on the needs of the application.

• Examples include creating an exception for invalid user input or a database connection failure.

• Custom exception handling can improve the overall robustness and reliability of ...read more

Singleton class ensures only one instance of a class is created and provides a global point of access to it.

• Use a private static variable to hold the instance of the class.

• Make the constructor private to prevent instantiation from outside the class.

• Provide a static method to access the instance, creating it if necessary.

Indexers in SQL servers are database objects that improve query performance by allowing faster data retrieval.

• Indexers are created on one or more columns of a table to speed up data retrieval operations.

• They work by creating a separate data structure that holds a copy of a portion of the data, allowing for faster searching and sorting.

• Indexers can be created on both clustered and non-clustered tables.

• They can be created using different algorithms, such as B-trees or hash tabl...read more

The life cycle of an MVC application involves the stages of initialization, request processing, rendering, and disposal.

• Initialization: Application starts, routes are configured, and controllers and views are initialized.

• Request processing: User sends a request, which is routed to the appropriate controller. Controller processes the request and interacts with the model and view.

• Rendering: Controller passes data to the view, which renders the HTML response.

• Disposal: After the ...read more

Asynchronous programming allows tasks to run concurrently, but can lead to complex code and potential race conditions.

• Difficult to debug due to non-linear flow of execution

• Potential for race conditions when multiple tasks access shared resources

• Complex error handling and callback hell can make code hard to read and maintain

Change is necessary for growth, improvement, and adaptation to new challenges.

• Change allows for innovation and progress

• Adapting to new technologies and market trends

• Improving efficiency and effectiveness of processes

• Responding to feedback and evolving customer needs

Facades in Laravel provide a simple and convenient way to access classes and services from the container.

• Facades act as static proxies to underlying classes, allowing easy access to their methods.

• They provide a clean and expressive syntax for accessing services.

• Facades are used to access Laravel's core services, such as the database, cache, and session.

• They can be used to access custom classes and services registered in the container.

• Facades help in decoupling the code by pro...read more

continue skips current iteration and moves to next, while break exits the loop entirely.

• continue is used to skip the current iteration of a loop and move to the next one

• break is used to exit the loop entirely and move on to the next statement

• continue is often used in loops with conditional statements to skip certain iterations

• break is often used in loops with conditional statements to exit the loop when a certain condition is met

Throw is a keyword used to throw an exception in Java. Thrown is the past participle of throw.

• throw is used to throw an exception in Java

• thrown is the past participle of throw

• throw is a keyword, while thrown is not

My strength lies in my ability to effectively lead and manage a team, while also being highly skilled in coding and problem-solving.

• Strong leadership and management skills

• Excellent coding and problem-solving abilities

• Ability to effectively communicate and collaborate with team members

• Proven track record of successfully delivering projects on time and within budget

• Experience in mentoring and guiding junior developers

• Adaptability and flexibility in handling changing priorities ...read more

JWT stands for JSON Web Token, a compact and secure way of transmitting information between parties as a JSON object.

• JWT is used for authentication and authorization purposes.

• It consists of three parts: header, payload, and signature.

• The header contains the algorithm used to sign the token.

• The payload contains the claims or information being transmitted.

• The signature is used to verify the authenticity of the token.

• JWTs can be used in various scenarios, such as single sign-on ...read more

A static method is a method that belongs to a class rather than an instance of the class.

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

• They are often used for utility functions that don't require any state information.

• Static methods cannot access non-static variables or methods.

• Example: Math.max() is a static method that returns the maximum of two numbers.

ref and out are keywords in C# used for passing arguments to methods by reference.

• ref keyword is used to pass arguments by reference, allowing the method to modify the value of the argument

• out keyword is similar to ref, but the argument does not have to be initialized before being passed to the method

• Example: void UpdateValue(ref int num) { num = num * 2; }

• Example: void GetValues(out int a, out int b) { a = 10; b = 20; }

UI Policies are used in ServiceNow to dynamically change the behavior of forms and fields based on conditions.

• UI Policies are used to set mandatory fields, read-only fields, and visibility conditions on forms.

• They are created using conditions and actions in the ServiceNow platform.

• For example, a UI Policy can be used to make a field mandatory when a certain condition is met.

An async method is a method that allows other code to run while it executes a long-running operation asynchronously.

• Async methods are marked with the async keyword.

• They return a Task or Task object.

• They can be awaited using the await keyword.

• Examples include HttpClient.GetAsync() and FileStream.ReadAsync().

Polymorphism is the ability of an object to take on many forms.

• It allows objects of different classes to be treated as if they were objects of the same class

• It is achieved through method overriding and/or method overloading

• Example: A parent class Animal can have child classes like Dog, Cat, and Bird, each with their own unique implementation of the method 'makeSound'

• Example: A method 'drawShape' can be overloaded to accept different types of shapes as arguments

I have 5 years of experience developing Android applications for various industries.

• Developed multiple Android apps using Java and Kotlin

• Experience with Android SDK, Android Studio, and third-party libraries

• Implemented features like push notifications, location-based services, and in-app purchases

• Optimized app performance and user experience through testing and debugging

• Worked on projects for e-commerce, healthcare, and entertainment sectors

AI is the simulation of human intelligence processes by machines, especially computer systems.

• AI involves machines performing tasks that typically require human intelligence, such as visual perception, speech recognition, decision-making, and language translation.

• Examples of AI include virtual assistants like Siri and Alexa, self-driving cars, recommendation systems like Netflix's algorithm, and facial recognition technology.

• AI can be categorized into narrow AI (focused on a ...read more

UI script knowledge involves understanding and implementing scripts for user interface interactions.

• Understanding of JavaScript and its libraries/frameworks like React, Angular, or Vue

• Experience with front-end technologies such as HTML, CSS, and AJAX

• Ability to create interactive and responsive user interfaces

• Knowledge of UI testing tools like Selenium or Cypress

Events are a higher-level concept that allows objects to communicate without knowing each other, while delegates are a type-safe function pointers.

• Events are based on the observer design pattern, where an object (the publisher) maintains a list of other objects (subscribers) that are interested in being notified when a certain event occurs.

• Delegates are similar to function pointers in C++, but with type safety and object-oriented features. They allow a method to be passed aro...read more