Essential algorithms · concurrency · streams · internals · interview ready
Java 26 maintains: array of Node<K,V> + red-black tree after threshold (TREEIFY_THRESHOLD=8). Hashing: (key.hashCode()) ^ (h >>> 16) → index = (n-1) & hash. Resize: 2 * capacity when load factor 0.75 reached. Java 26 further optimized memory layout & string deduplication.
🔗 Explore HashMap internalsSegment-free since Java 8: fine-grained locking on bins (synchronized on first node). Uses CAS for size, counter cells. Java 26 improves scalability under high contention & reduces memory footprint. Great for concurrent environments.
🔗 ConcurrentHashMap deep diveLeast Recently Used cache using LinkedHashMap (access-order) or custom via ConcurrentHashMap + ConcurrentLinkedDeque. In Spring Boot, can be used for caching layer or with @Cacheable and Caffeine.
📦 LRU example