Ernst & Young Technology Consultant Interview Questions and Answers for Freshers

Provided a scenario and asked to perform crud operations on the same.

Q1. 1. As I have only 1 year experience at that time so asked basic questions of java and spring boot like some annotations as Autowired and about actuator and all
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Q2. Prepare for mysql queries
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Technical discussion with client of the company again basic java and mysql queries questions

Round duration - 60 Minutes
Round difficulty - Medium

In this round, I was first asked a coding question related to Sliding Window Technique and then I was grilled on some major concepts from Java and Java Collections.

Q1. 
Smallest Subarray With K Distinct Elements
Given an array A consisting of N integers, your task is to find the smallest subarray of A that contains exactly K distinct integers.
If multiple such subarrays...read more
Ans. 
Find the smallest subarray in an array with exactly K distinct elements.
• Use a sliding window approach to keep track of the subarray with K distinct elements.

• Use a hashmap to store the frequency of each element in the window.

• Update the window by expanding or shrinking based on the number of distinct elements.

• Return the smallest subarray with K distinct elements and the smallest leftmost index.
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Q2. Why are Java Strings immutable in nature?
Ans. 
Java Strings are immutable to ensure thread safety, security, and optimization.
• Immutable strings prevent accidental changes, ensuring data integrity.

• String pooling allows for memory optimization by reusing common strings.

• Thread safety is guaranteed as strings cannot be modified concurrently.

• Security is enhanced as sensitive information cannot be altered once set.
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Q3. What do you know about the JIT compiler?
Ans. 
JIT compiler stands for Just-In-Time compiler, which compiles code during runtime for improved performance.
• JIT compiler translates bytecode into machine code at runtime

• It helps in optimizing performance by compiling frequently executed code

• Examples include Java HotSpot JIT compiler and .NET JIT compiler
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Q4. What is the difference between HashSet and HashMap in Java?
Ans. 
HashSet is a collection of unique elements, while HashMap is a key-value pair mapping.
• HashSet does not allow duplicate elements, HashMap allows duplicate keys but not values.

• HashSet uses a hash table to store elements, HashMap uses key-value pairs.

• Example: HashSet<String> set = new HashSet<>(); HashMap<String, Integer> map = new HashMap<>();
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Q5. Can you differentiate between ArrayList and Vector in Java?
Ans. 
ArrayList is non-synchronized and Vector is synchronized in Java.
• ArrayList is not synchronized, while Vector is synchronized.

• ArrayList is faster than Vector.

• Vector is thread-safe, while ArrayList is not.

• Example: ArrayList<String> list = new ArrayList<>(); Vector<String> vector = new Vector<>();
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Q6. Can you differentiate between HashMap and Hashtable?
Ans. 
HashMap and Hashtable are both data structures in Java used to store key-value pairs, but Hashtable is synchronized while HashMap is not.
• HashMap allows null values and one null key, while Hashtable does not allow null keys or values.

• HashMap is not synchronized and is not thread-safe, while Hashtable is synchronized and thread-safe.

• HashMap is faster than Hashtable for most operations, as it is not synchronized.

• HashMap i...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round started with some basic questions from Java 8 and then the interviewer started asking some questions from Spring Boot. At the end of the interview, I was also asked some questions from SQL and DBMS.

Q1. What are Java 8 streams?
Ans. 
Java 8 streams are a sequence of elements that support functional-style operations.
• Streams allow for processing sequences of elements in a functional way.

• They can be created from various data sources like collections, arrays, or I/O channels.

• Operations like filter, map, reduce, and collect can be performed on streams.

• Streams are lazy, meaning intermediate operations are only executed when a terminal operation is called...read more
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Q2. Write a Java 8 program to iterate through a Stream using the forEach method.
Ans. 
Java 8 program to iterate through a Stream using forEach method
• Create a Stream of elements using Stream.of() or any other method

• Use the forEach() method to iterate through the Stream and perform an action on each element

• Example: Stream.of(1, 2, 3, 4, 5).forEach(System.out::println);
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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 pre-configured settings and tools.
• Spring Boot eliminates the need for manual configuration by providing defaults for most settings.

• It includes embedded servers like Tomcat, Jetty, or Undertow, making it easy to run applications as standalone JAR files.

• Spring Boot also offers production-ready features like metrics, health checks...read more
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Q4. What is dependency injection?
Ans. 
Dependency injection is a design pattern in which components are given their dependencies rather than creating them internally.
• Dependency injection helps in achieving loose coupling between classes.

• It allows for easier testing by providing mock dependencies.

• There are three types of dependency injection: constructor injection, setter injection, and interface injection.
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Q5. Can you explain the @RestController annotation in Spring Boot?
Ans. 
The @RestController annotation in Spring Boot is used to define a class as a RESTful controller.
• Used to create RESTful web services in Spring Boot

• Combines @Controller and @ResponseBody annotations

• Eliminates the need for @ResponseBody annotation on each method

• Returns data directly in the response body as JSON or XML
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Q6. How does MVC work in Spring?
Ans. 
MVC in Spring is a design pattern that separates an application into three main components: Model, View, and Controller.
• Model represents the data and business logic of the application.

• View is responsible for rendering the user interface based on the data from the Model.

• Controller acts as an intermediary between Model and View, handling user input and updating the Model accordingly.

• Spring MVC provides annotations like @...read more
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Q7. What are a few features of Spring Boot?
Ans. 
Spring Boot is a framework that simplifies the development of Java applications by providing pre-configured setups.
• Auto-configuration: Spring Boot automatically configures the application based on dependencies added to the project.

• Embedded server: Spring Boot comes with an embedded Tomcat, Jetty, or Undertow server for easy deployment.

• Actuator: Provides production-ready features like monitoring, metrics, and health che...read more
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Round duration - 30 Minutes
Round difficulty - Easy

This was a Technical Cum HR round where I was first asked some basic Java related concepts and then we discussed
about my expectations from the company , learnings and growth in the forthcomig years. I would suggest be honest and
try to communicate your thoughts properly in these type of rounds to maximise your chances of getting selected.