Got a Java backend interview coming up? This is the revision sheet I wish I’d had. With my 5 years of experience in backend development in java, I come up with the questions that are frequently asked in the interviews.
What's inside (3 pages, A4 Printable)
☕ Core Java: OOP, keywords, JVM memory and GC, String vs StringBuilder, the Collections complexity table, HashMap internals, exceptions, immutable classes, Java 11–21 features
⚡ Java 8: Functional interfaces, method references, the stream pipeline, Optional, and 15+ ready-to-use Stream coding questions.
🧵 Multithreading: Thread lifecycle, sleep vs wait vs join, synchronized vs ReentrantLock, Atomic, ThreadLocal, CountDownLatch/CyclicBarrier/Semaphore, thread pool sizing, CompletableFuture, producer-consumer, thread-safe Singleton, deadlocks
🌱 Spring Boot: IoC/DI, auto-configuration, bean scopes and lifecycle, REST controllers, global exception handling, Spring Data JPA and the N+1 problem, @Transactional propagation and pitfalls, Spring Security 6 with JWT, profiles, AOP, Actuator, testing, microservices stack
Who it’s for: Java developers with 1–6 years of experience preparing for SDE-1, SDE-2 or Senior Java Developer interviews.
