40+ DHL Supply Chain Interview Questions and Answers

Interview questions for Senior Software Engineer position

• OOPS concepts include inheritance, polymorphism, encapsulation, and abstraction

• Abstract classes cannot be instantiated while interfaces cannot have implementation

• SQL query to get second highest salary: SELECT MAX(salary) FROM table_name WHERE salary < (SELECT MAX(salary) FROM table_name)

• Index in SQL server is a data structure that improves the speed of data retrieval operations

• Primary key uniquely identifies a record, f...read more

I have used both Material UI and Bootstrap for styling.

• I have used Material UI for a project that required a more modern and sleek design.

• I have used Bootstrap for a project that required a more traditional and familiar design.

• Both frameworks have their strengths and weaknesses, and I choose the one that best fits the project's needs.

• I am also familiar with other styling frameworks such as Semantic UI and Foundation.

APIs are used for direct communication between systems, while event driven systems are used for asynchronous communication based on events.

• Use APIs when you need direct communication between systems, such as retrieving data from a database or integrating with a third-party service.

• Depend on event driven systems when you want to trigger actions based on events, such as user interactions or system notifications.

• APIs are synchronous, while event driven systems are asynchronous.

• A...read more

I enjoy working on product-based projects that involve complex problem-solving using DSA.

• I prefer projects that have a clear end goal and tangible impact on users

• I enjoy working on projects that require me to think outside the box and come up with creative solutions

• I am comfortable working with DSA and enjoy using them to optimize code and improve performance

• Examples of projects I have enjoyed working on include developing a recommendation engine for an e-commerce platform an...read more

Data flows from frontend to backend in Asp.net core through HTTP requests and responses.

• Frontend sends HTTP requests to backend API endpoints

• Backend processes the requests and sends back HTTP responses

• Data can be passed in the request body, query parameters, or headers

• Example: Frontend sends a POST request to create a new user, backend receives the request, processes it, and sends a success response

Virtual DOM is a lightweight copy of the actual DOM, used to improve performance by minimizing actual DOM manipulation.

• Virtual DOM is a concept used in ReactJS.

• It is a lightweight copy of the actual DOM.

• It is used to improve performance by minimizing actual DOM manipulation.

• When a change is made to the actual DOM, the Virtual DOM is updated.

• The Virtual DOM then calculates the difference between the previous and updated state.

• Only the necessary changes are then made to the act...read more

Creating a Spring Boot project using CLI and understanding the difference between Prototype and Request bean scopes.

• To create a Spring Boot project using CLI, use the 'spring init' command followed by project details

• Prototype bean scope creates a new instance of a bean every time it is requested

• Request bean scope creates a new instance of a bean for each HTTP request

• Prototype beans are not thread-safe, while Request beans are thread-safe

• Example: 'spring init --name myproject ...read more

Using Java stream to find the second highest integer in a list

• Use Java stream to convert the list to IntStream

• Sort the IntStream in descending order

• Skip the first element to get the second highest integer

Spring Boot 3 introduces new features like improved performance, enhanced security, and support for the latest Java versions.

• Improved performance with faster startup times and reduced memory consumption

• Enhanced security features such as built-in support for OAuth 2.0 and JWT

• Support for the latest Java versions like Java 17

• Introduction of new modules and APIs for easier development and integration

To bind events in React JS, use the 'on' prefix followed by the event name in camelCase.

• Use the 'on' prefix followed by the event name in camelCase (e.g. onClick, onSubmit)

• Pass a function as the event handler (e.g. onClick={() => console.log('Button clicked')})

• Bind 'this' to the event handler function if it uses 'this' (e.g. onClick={this.handleClick.bind(this)})

• Use arrow functions to automatically bind 'this' (e.g. onClick={() => this.handleClick()})

Functional interfaces in Java are interfaces with only one abstract method, used for lambda expressions and functional programming.

• Functional interfaces can have multiple default methods but only one abstract method.

• They are used for lambda expressions and functional programming in Java.

• Examples include Runnable, Callable, Comparator, etc.

Singleton design pattern ensures a class has only one instance and provides a global point of access to it.

• Singleton pattern restricts the instantiation of a class to one object.

• It involves a static member in the class, a private constructor, and a static method to return the instance.

• Example: Singleton pattern can be used in database connections, logging classes, and thread pools.

Event driven architecture is a design pattern where the flow of the system is determined by events.

• Events are generated by different components and trigger actions in other components.

• Decoupling of components allows for better scalability and flexibility.

• Commonly used in systems where real-time processing and responsiveness are crucial.

• Examples include message queues like Kafka, event sourcing, and pub/sub systems.

Class is a blueprint for creating objects with properties and methods, while functional component is a function that returns JSX.

• Class can have state and lifecycle methods, while functional component cannot.

• Functional component is simpler and easier to read and test.

• Class can be extended and reused, while functional component cannot.

• Example of class component: class MyComponent extends React.Component {}

• Example of functional component: const MyComponent = () => { return

  Hello...read more

JavaScript data types refer to the different types of values that can be stored and manipulated in JavaScript.

• JavaScript has several data types including string, number, boolean, object, function, and undefined.

• Examples: 'hello' (string), 42 (number), true (boolean), { key: 'value' } (object), function() { } (function), undefined.

• Data types can be dynamically assigned in JavaScript, meaning a variable can change its type during runtime.

Implementing CRUD operations using Spring Boot and JPA connection

• Create Entity class with @Entity annotation

• Create Repository interface extending JpaRepository

• Use @RestController and @Autowired for Controller class

• Implement methods for Create, Read, Update, Delete operations

Interface defines a contract for a class to implement while Abstraction hides the implementation details.

• Interface is a blueprint of a class that defines what methods a class must implement.

• Abstraction is a concept where only relevant information is shown and irrelevant details are hidden.

• Interfaces can have multiple inheritance while Abstraction can be achieved through abstract classes or interfaces.

• Example: Interface 'Shape' may have methods like calculateArea() and calcula...read more

JS Event Loop is the mechanism that allows JavaScript to perform non-blocking operations by handling asynchronous tasks.

• Event Loop is responsible for executing code, collecting and processing events, and executing queued sub-tasks.

• It consists of a Call Stack, Web APIs, Callback Queue, and Microtask Queue.

• Example: setTimeout() function in JavaScript uses the Event Loop to schedule a function to run after a specified time.

Spring Security is used for authentication and authorization in Java applications.

• Configuring security settings in XML or Java configuration

• Defining authentication providers and user roles

• Securing endpoints with annotations like @PreAuthorize

• Customizing login and logout pages

Python is a high-level, interpreted programming language known for its simplicity, readability, and versatility.

• Python is used for web development, data analysis, artificial intelligence, scientific computing, and more.

• It has a large standard library and supports multiple programming paradigms.

• Python code is easy to read and write, making it a popular choice for beginners and experienced developers alike.

• Some popular Python frameworks include Django, Flask, and Pyramid.

• Python...read more

Hooks are functions that allow you to use state and other React features in functional components. useMemo() is a hook that memoizes a function's result.

• Hooks are used in functional components to access state and lifecycle methods

• useMemo() is used to memoize a function's result to improve performance

• Example: const [count, setCount] = useState(0);

• Example: const memoizedValue = useMemo(() => computeExpensiveValue(a, b), [a, b]);

Arrow functions are a shorthand syntax for writing functions in JavaScript.

• Arrow functions have a concise syntax and do not bind their own 'this' keyword.

• They are commonly used in functional programming and with array methods like map, filter, and reduce.

• Arrow functions cannot be used as constructors and do not have a prototype property.

• They are also not suitable for methods that require the 'this' keyword to be bound to the object calling the method.

Angular is a popular front-end framework for building dynamic web applications.

• Developed and maintained by Google

• Uses TypeScript for building applications

• Follows the component-based architecture

• Supports two-way data binding

• Has a powerful CLI for scaffolding projects

I am available to start immediately.

• I am available to start immediately

• I can start as soon as needed

• I am ready to begin work right away

Caching is the process of storing frequently accessed data in a temporary storage area to improve performance.

• Caching helps reduce the load on the primary data source by serving frequently accessed data from a faster storage medium.

• Common caching strategies include in-memory caching, disk caching, and distributed caching.

• Examples of caching include browser caching of web pages to reduce load times and database query result caching to speed up data retrieval.

Link is used to connect external CSS or JavaScript files in HTML, while import is used to bring in modules or components in JavaScript.

• Link is used in HTML to connect external CSS files, while import is used in JavaScript to bring in modules or components.

• Link is a HTML tag, while import is a JavaScript statement.

• Link is used for styling and layout, while import is used for code organization and modularity.

• Example: for link, import React from 'react'; for import.

Optimization techniques in Spark improve performance by reducing unnecessary computations and data shuffling.

• Use partitioning to reduce data shuffling and improve parallelism

• Cache intermediate results to avoid recomputation

• Use broadcast variables for small lookup tables to avoid unnecessary data shuffling

• Avoid unnecessary transformations and actions in the code

Functions are reusable code blocks that return a value, while stored procedures are precompiled SQL statements that can perform multiple operations.

• Functions return a value, while stored procedures do not necessarily return a value.

• Functions can be used in SQL queries, while stored procedures are called using EXECUTE statement.

• Functions are easier to test and debug compared to stored procedures.

• Stored procedures can contain multiple SQL statements and can be used to perform c...read more

TMG event refers to a type of event in the Windows operating system that is related to the Threat Management Gateway.

• TMG events are generated by the Microsoft Forefront Threat Management Gateway (TMG) to provide information about network activity and security events.

• Examples of TMG events include firewall rule violations, denial of service attacks, and malware detection.

• TMG events can be monitored and analyzed to improve network security and troubleshoot issues.

• Understanding ...read more

Debouncing is a technique used in software development to prevent multiple rapid triggers of an event from being processed.

• Debouncing helps in improving performance by reducing unnecessary event processing.

• It involves setting a delay before allowing the event to be triggered, ensuring only one event is processed.

• Commonly used in user interface interactions like button clicks to prevent multiple rapid clicks from being registered.

• Example: Debouncing can be used to prevent a se...read more

Node.js is a runtime environment that allows you to run JavaScript on the server side.

• Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient.

• It is built on the V8 JavaScript engine and uses an event loop for handling asynchronous operations.

• Node.js allows you to easily build scalable network applications.

• It has a large ecosystem of libraries and frameworks, such as Express.js for building web applications.

A small program using Java Streams to filter a list of strings starting with 'A'

• Create a list of strings

• Use Java Streams to filter strings starting with 'A'

• Print the filtered strings

CI/CD stands for Continuous Integration/Continuous Deployment. It is a software development practice where code changes are automatically built, tested, and deployed.

• CI/CD automates the process of integrating code changes into a shared repository and deploying them to production.

• Continuous Integration involves automatically building and testing code changes as soon as they are pushed to the repository.

• Continuous Deployment involves automatically deploying code changes to prod...read more

Ansible code example for automating software deployment

• Use Ansible playbooks to define tasks and configurations

• Utilize Ansible modules for managing servers and applications

• Leverage Ansible roles for organizing and reusing code

• Example: ansible-playbook deploy.yml

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

• Design patterns provide general solutions to recurring design problems in software development.

• They help in creating maintainable, scalable, and efficient code.

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

I have over 8 years of experience in developing software applications, with expertise in Java, Python, and SQL.

• Developed web applications using Java Spring framework

• Automated testing processes with Python scripts

• Optimized database queries using SQL indexes

Spring is a framework for building Java applications, while Spring Boot is a tool for quickly creating Spring applications. JPA is a Java specification for ORM.

• Spring is a comprehensive framework for building Java applications with features like dependency injection and aspect-oriented programming.

• Spring Boot is a tool that simplifies the process of creating Spring applications by providing defaults and auto-configuration.

• JPA (Java Persistence API) is a Java specification for...read more

Web Config uses configuration files to store settings for web applications.

• Web.config file is an XML file used in ASP.NET applications to store configuration settings

• Settings in Web.config file include connection strings, app settings, custom error pages, etc.

• Changes to Web.config file do not require recompilation of the application

Use SQL query with GROUP BY and HAVING clause to find duplicates in a table.

• Use GROUP BY clause to group rows with same values

• Use HAVING clause to filter out groups with count greater than 1

• Example: SELECT column_name, COUNT(*) FROM table_name GROUP BY column_name HAVING COUNT(*) > 1

ACID properties are a set of properties that guarantee the reliability of database transactions.

• ACID stands for Atomicity, Consistency, Isolation, and Durability.

• Atomicity ensures that all operations in a transaction are completed successfully or none at all.

• Consistency ensures that the database remains in a consistent state before and after the transaction.

• Isolation ensures that transactions are executed independently of each other.

• Durability ensures that once a transaction ...read more