Hey developers! 👋

While prepping for Java Backend roles, I noticed how time-consuming it is to dig through lengthy documentation, verbose blogs, or multi-hour videos right before an interview.

To streamline last-minute revision, I put together a concise 35-Question Cheat Sheet covering core Java and Spring Boot internals.

🔑 Core Topics Covered in the Cheat Sheet

1. Core Java & Collections Internals

HashMap vs ConcurrentHashMap: Bucket structure, segment locking vs CAS, rehashing mechanics, and thread-safety trade-offs.

String Pool & Immutability: Heap memory allocation, garbage collection behavior, and string literals vs new String() .

2. Multithreading & Concurrency

Concurrency Primitives: volatile keyword guarantees, visibility vs atomicity.

Executors & Futures: ExecutorService thread-pool behavior, rejection policies, and CompletableFuture async pipelines.

3.…