I am currently working as a Senior Software Engineer in a fintech company with a total of 5.5 years of experience. Below is my interview experience with EPAM.

Round 1

This round involved Java-based coding tasks and conceptual questions related to Java 8 features and collections.

Coding Questions:
Use Streams to implement below:

1. Print the list of all employees

list.forEach(e -> System.out.println(e.getId() + " " + e.getName() + " " + e.getDesignation()));

2. Collect a list of employee IDs divisible by 2

List<Integer> result = list.stream()
    .filter(e -> e.getId() % 2 == 0)
    .map(Employee::getId)
    .collect(Collectors.toList());

3. Sort the employee list in ascending and descending order of ID

Collections.sort(list, (a, b) -> Integer.compare(a.getId(), b.getId()));

More in depth questions were asked from below topics.

• Functional Interface
• Collectors & Optional
• map vs flatMap
• Method references
• System.out.println() vs System.out::println
• Object::printVal
• Reentrant Locks
• Blocking vs Non-blocking calls
• CompletableFuture Object
• Marker Interface (Serializable, Cloneable)
• equals() and hashCode() contract
• TreeSet vs TreeMap
• Comparable vs Comparator
• Deep Cloning vs Shallow Cloning
• Heap, Stack, Metaspace
• Classpath
• Checked vs Unchecked Exceptions
• SQLException Handling
• FileHandler
• String Comparison in Java:

String a = new String("Vijai");
String b = new String("Vijai");
String c = "Vijai";
String d = "Vijai";

System.out.println(a == b); // false
System.out.println(a.equals(b)); // true

• Coding Question: Find the longest Substring Without Repeating Characters

Example Input & Output:

Input: "abcadcbb" → Output: 4 (Substring: "bcad")

Input: "pwwkew" → Output: 3 (Substring: "wke")

Optimized solution: O(n) time complexity.

Round 2

This round covered dependency injection, Spring Boot, transaction management, and system design.

Topics Covered:

• Spring Boot Starter Dependencies
• Spring Actuator (Health Check, Logging, Tomcat)
• Dependency Injection in Plain Java (without Spring)
• @Primary vs @Qualifier
• @Transactional
• SOLID Principles
• Dependency Inversion Principle
• Liskov Substitution Principle
• Spring Annotations
• @ControllerAdvice
• AOP (@Before, @After)
• Singleton Pattern & Thread Safety
• Factory Pattern & Use Cases
• Strategy Pattern in Java
• Observer Pattern
• Mockito & Unit Testing Best Practices
• Custom Exception Handling in Spring
• Handling Service Failures in Distributed Systems
• Microservices Communication Strategies
• Multithreading and Concurrency
• Reentrant Locks vs Synchronized Blocks
• Database Transactions & ACID Properties
• Event-Driven Architecture
• LLD design (Don't remember the exact question)

Verdict: Ghosted after round 2. Was told Round 3 will be held later as feedback of Round 2 was neither positive, not negative.