🚀 Core Java & Spring Boot 3.
x
Q1: What are the key improvements in Java 21 compared to previous versions?
✅ Answer:
Java 21 introduces several long-term support (LTS) features, including:
Virtual Threads (Project Loom) → Reduces thread management overhead, improving
concurrency.
Pattern Matching for Switch (JEP 440 & 441) → Enables concise and expressive code.
Record Patterns (JEP 440) → Simplifies data handling and deconstruction.
Sequenced Collections (JEP 431) → Ensures predictable iteration order across
collection types.
Scoped Values (JEP 446) → Provides a more efficient alternative to ThreadLocal.
👉 These features help in writing more performant, readable, and concurrent applications.
Q2: What are the main changes in Spring Boot 3.x compared to 2.x?
✅ Answer:
Java 17+ is required → Uses new Java features like records and virtual threads.
Jakarta EE 10 migration → Moves from javax.* to jakarta.* package namespace.
GraalVM native image support → Enables faster startup time and lower memory
footprint.
Enhanced observability → Built-in support for Micrometer and OpenTelemetry.
New AOT processing → Improves performance by pre-compiling certain aspects of
applications.
👉 These updates make Spring Boot faster, more memory-efficient, and optimized for cloud-
native applications.
📡 Asynchronous Communication & Apache Pulsar
Q3: How does Apache Pulsar differ from Kafka for event-driven architectures?
✅ Answer:
Feature Apache Pulsar Kafka
Multi-tenancy Native support Requires separate clusters
Geo-replication Built-in Requires additional setup
Message storage Tiered storage (cheaper for long-term) Log-based storage
Scalability Decouples compute & storage Tight coupling
Topic partitioning Dynamically assigned Static at topic creation
👉 Apache Pulsar is a better fit for multi-region, cloud-native, and large-scale streaming
applications.
Q4: What is AsyncAPI, and why is it important?
✅ Answer:
AsyncAPI is an open-source standard for documenting and defining asynchronous APIs,
similar to OpenAPI for REST APIs.
Benefits:
Standardizes event-driven communication.
Improves API documentation for messaging-based systems (Pulsar, Kafka, RabbitMQ).
Enables code generation for producers & consumers.
👉 Helps teams maintain consistency and interoperability in microservices communication.
⚙️ CI/CD & Deployment Strategies
Q5: What are best practices for designing an efficient CI/CD pipeline?
✅ Answer:
Multi-stage builds → Optimize Docker images to reduce size.
Automated testing (Unit + Integration + Performance) → Use JUnit, Mockito,
Testcontainers.
Feature flags → Enable Canary Deployments without redeploying.
GitOps & Infrastructure as Code (IaC) → Use ArgoCD, Terraform.
Rollback strategies → Implement blue-green or canary deployments.
Observability → Integrate Prometheus, Grafana, OpenTelemetry for monitoring.
👉 Ensures fast, reliable, and scalable deployments.
📊 Technical & Functional Analysis
Q6: How do you approach analyzing a complex business problem in software
development?
✅ Answer:
1. Understand the business needs → Work closely with stakeholders to define
requirements.
2. Identify constraints → Scalability, security, and performance considerations.
3. Evaluate possible architectures → Monolithic vs Microservices, Synchronous vs
Asynchronous.
4. Design domain models → Use DDD (Domain-Driven Design) principles.
5. Create PoCs (Proof of Concepts) → Validate solutions before full implementation.
6. Document & communicate findings → Ensure alignment across teams.
👉 Helps deliver scalable, maintainable, and business-aligned solutions.
️ Bonus: Additional Java & Spring Boot 3.x Questions
Q7: How would you migrate an existing Spring Boot 2.x application to 3.x?
✅ Answer:
1. Upgrade Java version to 17 or 21.
2. Update dependencies (spring-boot-starter-parent to 3.x).
3. Migrate javax.* to jakarta.*.
4. Refactor deprecated APIs (e.g., Hibernate, Jackson).
5. Test application performance & behavior with load tests.
Q8: How do you handle transactional integrity in an asynchronous event-driven
system?
✅ Answer:
Transactional Outbox Pattern → Ensures message reliability by storing events in a DB
table before publishing.
SAGA Pattern → Manages distributed transactions across multiple microservices.
Eventual Consistency → Uses retries and compensating transactions.
👉 Prevents data loss and ensures integrity across services.
Final Thoughts
This Q&A guide covers the core aspects of this Senior Java Developer role, including:
✅ Java 21 & Spring Boot 3.x
✅ Asynchronous messaging & Apache Pulsar
✅ CI/CD and deployment strategies
✅ Technical & functional analysis
Would you like additional mock interview questions or coding challenges? 🚀
