American Express Full Stack Developer Interview Questions, Process, and Tips

Round duration - 60 Minutes
Round difficulty - Medium

This round had questions mainly from Java 8 and its important features followed by some questions from Spring Boot.

Q1. What are Java 8 streams?
Ans. 
Java 8 streams are a sequence of elements that can be processed in parallel or sequentially.
• Streams provide a functional programming approach to process collections in Java.

• They allow for concise and expressive code.

• Streams can be used to filter, map, reduce, and perform other operations on data.

• Example: List numbers = Arrays.asList(1, 2, 3, 4, 5); numbers.stream().filter(n -> n % 2 == 0).forEach(System.out::println);

• T...read more
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Q2. Write a Java 8 program to iterate through a Stream using the forEach method.
Ans. 
A Java 8 program to iterate a Stream using the forEach method.
• Create a Stream object from a collection or array

• Use the forEach method to perform an action on each element of the Stream

• The action can be a lambda expression or a method reference
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Q3. How does Spring Boot work?
Ans. 
Spring Boot is a framework that simplifies the development of Java applications by providing default configurations and dependencies.
• Spring Boot eliminates the need for manual configuration by providing sensible defaults.

• It uses an embedded server, such as Tomcat or Jetty, to run the application.

• Spring Boot automatically configures the application based on the dependencies added to the project.

• It promotes convention ov...read more
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Q4. What is dependency injection?
Ans. 
Dependency Injection is a design pattern where the dependencies of a class are provided externally rather than being created within the class itself.
• Dependency Injection helps in achieving loose coupling between classes.

• It allows for easier testing and maintenance of code.

• In Spring Boot, dependencies are injected using annotations like @Autowired.

• Example: In a Spring Boot application, if a class requires a database con...read more
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Q5. Can you explain the @RestController annotation in Spring Boot?
Ans. 
The @RestController annotation in Spring Boot is used to mark a class as a RESTful controller.
• It combines the @Controller and @ResponseBody annotations.

• It eliminates the need for annotating each method with @ResponseBody.

• It automatically serializes the return value of the methods into JSON/XML response.

• It is commonly used to build RESTful web services in Spring Boot.
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Q6. What are the different methods of session management in Servlets?
Ans. 
Different methods of session management in Servlet
• Cookies

• URL Rewriting

• Hidden Form Fields

• Session Tracking API

• HTTP Session
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Round duration - 60 Minutes
Round difficulty - Medium

This was a preety much mixed round ranging questions from Java , MVC to DBMS , Web Security and API Design. More emphasis was given on the fundamentals of the subject rather than the advanced topics.

Q1. What is CORS in MVC and how does it work?
Ans. 
CORS in MVC is Cross-Origin Resource Sharing, a mechanism that allows restricted resources on a web page to be requested from another domain.
• CORS is a security feature implemented in web browsers to prevent cross-origin requests by default.

• It works by adding specific HTTP headers to the server's response, indicating which origins are allowed to access the resources.

• In MVC, CORS can be configured using the 'EnableCors' ...read more
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Q2. Can you explain in brief the role of different MVC components?
Ans. 
MVC components include Model, View, and Controller. Model represents data and business logic, View displays the data, and Controller handles user input and updates the Model and View.
• Model: Represents data and business logic

• View: Displays the data to the user

• Controller: Handles user input and updates the Model and View
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Q3. What is the difference between a clustered index and a non-clustered index?
Ans. 
Clustered index determines the physical order of data in a table, while non-clustered index has a separate structure.
• Clustered index determines the physical order of data in a table

• Non-clustered index has a separate structure that includes a copy of the indexed columns and a pointer to the actual data

• A table can have only one clustered index, but multiple non-clustered indexes

• Clustered index is faster for retrieving la...read more
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Q4. What is SQL injection?
Ans. 
SQL injection is a web security vulnerability that allows an attacker to manipulate a database query to execute unauthorized actions.
• SQL injection occurs when user-supplied data is not properly validated or sanitized before being used in an SQL query.

• Attackers can exploit this vulnerability to bypass authentication, retrieve sensitive data, modify or delete data, or even execute arbitrary commands.

• To prevent SQL inject...read more
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Q5. What are the advantages of web services?
Ans. 
Web services offer advantages such as interoperability, scalability, reusability, and platform independence.
• Interoperability: Web services allow different applications to communicate and share data regardless of the programming languages or platforms they are built on.

• Scalability: Web services can handle a large number of requests and can be easily scaled up or down to meet changing demands.

• Reusability: Web services pr...read more
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Round duration - 45 Minutes
Round difficulty - Medium

This round started with some questions from Frontend Web Development primarily from HTML and CSS followed by some questions from DevOps and Git. The interviewer was quite satisfied by my answers and overall this round went preety well.

Q1. How can you optimize the loading of website assets?
Ans. 
Optimize website assets loading by minimizing file sizes, leveraging caching, and using asynchronous loading.
• Minimize file sizes by compressing images, minifying CSS and JavaScript files

• Leverage caching by setting appropriate cache headers and using a content delivery network (CDN)

• Use asynchronous loading techniques such as lazy loading, deferred loading, and async/defer attributes

• Combine and bundle multiple files to r...read more
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Q2. What are the new tags for media elements introduced in HTML5?
Ans. 
The new tags in Media Elements in HTML5 are
• The

• The

• Both tags support various attributes and can be styled using CSS.

• Example:

• Example:
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Q3. Can you explain a use case for Docker?
Ans. 
Docker is a containerization platform that allows developers to package applications with their dependencies for easy deployment and scalability.
• Docker enables developers to create lightweight, isolated containers that can run on any operating system.

• It simplifies the deployment process by ensuring that the application and its dependencies are bundled together, eliminating compatibility issues.

• Docker allows for easy sc...read more
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Q4. What is the difference between 'git pull' and 'git fetch'?
Ans. 
Git pull combines git fetch and git merge, while git fetch only downloads new data from a remote repository.
• Git pull is used to update the local branch with the latest changes from the remote repository.

• Git fetch only downloads new data from the remote repository, but does not integrate it into the local branch.

• Git pull is a combination of git fetch and git merge commands.

• Git fetch is useful to see what changes have be...read more
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Easy Questions based on Array and String Data Structure

Q1. How does a website URL works
Ans. 
A website URL is a unique address that identifies a web page on the internet.
• URL stands for Uniform Resource Locator

• It consists of a protocol (http/https), domain name, and path

• The domain name is translated to an IP address using DNS

• The path specifies the location of the resource on the server

• Example: https://www.google.com/search?q=url
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Q2. Event loop in Javascript
Ans. 
Event loop is a mechanism in JavaScript that handles asynchronous operations.
• Event loop continuously checks the call stack and the task queue.

• If the call stack is empty, it takes the first task from the queue and pushes it to the call stack.

• Callbacks are added to the task queue when an asynchronous operation is completed.

• Event loop ensures that the code runs in a non-blocking way.

• Example: setTimeout() function adds a c...read more
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Q3. Simple Coding based, Given an array, find a pair with sum = k.
Ans. 
Given an array, find a pair with sum = k.
• Use a hash table to store the difference between k and each element in the array.

• Iterate through the array and check if the current element is present in the hash table.

• If it is present, return the pair of elements that add up to k.
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Q1. Java Exceptions, Streams
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Q2. Find first minimum and maximum number in an array using streams
Ans. 
Find first minimum and maximum number in an array using streams
• Use IntStream to convert array to stream of integers

• Use min() and max() methods to find minimum and maximum values

• Use findFirst() method to get the first occurrence of minimum and maximum values
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Q1. They grind u in javascript,typescript
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Q2. Html css, angular
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Q3. Deep preparation needed
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Question Related to the DP and the Graph

Q1. Kth Max Element in a Array
Ans. 
Find the Kth maximum element in an array of strings.
• Sort the array in descending order.

• Return the element at index K-1.
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Q2. Coin Change and optimization through DP
Ans. 
Coin change problem can be solved using dynamic programming to find the minimum number of coins needed to make a certain amount of change.
• Use dynamic programming to build up solutions for smaller subproblems

• Start by initializing an array to store the minimum number of coins needed for each amount from 0 to the target amount

• Iterate through each coin denomination and update the array with the minimum number of coins need
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Q1. Project include in your Resume
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Q2. HR common question
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MCQ test consisting of 70 mcqs in 75 minutes from aptitude english and cs fundamentals. If cleared next paper 2 coding qs medium level

Q1. Two sum leetcode problem
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Q2. What problems you faced in your project
Ans. 
I faced challenges with integrating third-party APIs and debugging complex logic.
• Difficulty in understanding and implementing third-party APIs

• Issues with data synchronization between different systems

• Troubleshooting complex logic errors

• Managing dependencies and version conflicts

• Time constraints affecting problem-solving
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DP graphs strings it was good

Q1. Reverse a linkded list
Ans. 
Reverse a linked list by changing the direction of pointers
• Start with three pointers: current, previous, and next

• Iterate through the list, updating pointers to reverse the direction

• Return the new head of the reversed list
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Q2. Print fibonacci series
Ans. 
The Fibonacci series is a sequence of numbers where each number is the sum of the two preceding ones.
• Start with two variables initialized to 0 and 1

• Loop through desired number of iterations, adding the previous two numbers to get the next number

• Print or store each number in the series
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Q1. Why do you want to switch
Ans. 
I want to switch to explore new technologies and challenges in a different industry.
• Interested in learning new skills and technologies

• Seeking new challenges and opportunities for growth

• Want to explore different industry perspectives
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Q2. Salry expectations
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Q1. Question on oop concepts
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Q2. Coding questions
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