Java Interviewer-Makakmayum

If you are a backend engineer, you have to understand SOLID principle without any exception. I have received multiple dms asking me to explain it in an understandable way. So here we go. Save this, you'll thank me later. SOLID is a set of five design principles that help…

Notification Systems 101: Designing a notification service 1. what even is a notification system? it’s a system that delivers alerts to users through: ‣ in-app (that bell icon) ‣ push notifications (on mobile or web) ‣ email (for things that can wait) the goal? to tell the…

Design patterns are important and evolving , here are the old vs new approaches that you have to know for interview and work purposes similarly: ⇒Singleton Pattern vs. Dependency Injection: →Old Pattern: Singleton —ensured a single instance of a class —used for…

Java/Backend interview Scenario-Based Question on Distributed lock: You design a critical service, say order processing, that runs on multiple instances in Kubernetes. To prevent a race condition where two instances process the same order, you implement a distributed lock using…

Java/backend interview question: Recently AWS had outages in US-EAST-1 region. How would you architect a Microservice's deployment and surrounding infrastructure to ensure it can survive the failure of a single instance, a database failure, or even the failure of an entire data…

As a software/backend engineer, knowing Microservice Communication Patterns helps you build scalable apps, helps you in system design interviews. I'm summarizing them here: REST (HTTP) →simple and synchronous →stateless operations →JSON/XML formats →easy debugging gRPC…

One of the most important concepts: Idempotency for Java/Backend engineers: Short Question: How would you define idempotency, and what makes it a critical concept for Microservices? Scenario based: A PaymentService exposes a POST /payments endpoint. Due to a network issue, a…

As a Java developer, master Concurrency, Parallelism, Multithreading, and Locking to build efficient, scalable applications: →Concurrency Fundamentals a. Task execution b. Shared resources c. Race conditions d. Deadlocks avoidance e. Livelocks detection f. Starvation prevention…

As a software engineer, learn below to master System Design and build scalable, reliable systems: →Fundamentals a. System components (clients, servers, databases, caches) b. High-level vs. low-level design c. CAP Theorem d. Consistency models (eventual, strong, causal) e. ACID…

As a Backend engineer, learn below to move beyond CRUD APIs: →Security a. Authentication & Authorization b. Cryptography c. Encryption Algorithms d. OWASP Top 10 e. SIEM, IDS, IPS, etc. f. misc: OAuth 2.0, JWT, etc. g. CORS h. Security headers(CSP, HSTS…

As a Java/Backend engineer, learn these properly to be a better engineer instead of trying to learn every new fancy tech or a language: To organize data efficiently: Data Structure To optimize problem solving: Algorithms To protect data endpoints: API Security To enable…

For AWS US east outage issue, below post tells why we need to consider between Consistency and Availability as network Partition is a fundamental part of life in a distributed system and we have to sacrifice either C or A in most cases.

As a Java/backend developer, knowing Microservices patterns is mandatory to be a better developer and also to perform better in any interview. I am providing an exhaustive list of the PATTERNS available in Microservices. Save them, learn them, as a developer when you learn these…

Java/Microservice interview question: ⇒How to debug and Optimize a Slow Microservice Due to External API Calls? 1. Diagnose and Confirm (Don't Guess) → confirm the external API is the true bottleneck. → Tracing: Use distributed tracing (Telemetry or Zipkin) to measure the…

Most important Springboot annotations that are used the most and also asked the most during interviews: ⇒Core Spring Boot Annotations → @ SpringBootApplication: Combines @ Configuration, @ EnableAutoConfiguration, and @ ComponentScan Entry point for a Spring Boot app → @…

Java/Springboot interview question: Question: To build a fast API, you must fetch data from multiple microservices in parallel. How does this requirement influence your choice between RestTemplate, WebClient, and a Feign Client? RestTemplate: Best for a simple, blocking script…

In an actual Java interview, asking a simple question like below doesn't actually test in-depth knowledge of a candidate. So a scenario is introduced to check the same. Short Question: How can you force three threads—T1, T2, and T3—to execute in a specific sequence, one after…

Java interview scenario based questions on Exceptions: Short Question 1: Can a static block throw an exception? Scenario based: You have a class that initializes a critical static resource in a static block. This initialization process might fail and throw an exception. What…

As a Java/backend engineer, at one point these system design concepts become inescapable. Understand these concepts properly to be a better engineer and also to perform better during interviews: → APIs (Application Programming Interfaces): A set of rules and protocols that…