advanced~4h
TreeMap, NavigableMap, and the Specialized Map Family
How TreeMap keeps keys sorted using a self-balancing red-black tree, the NavigableMap operations that sorting unlocks, and a tour of ConcurrentHashMap, EnumMap, WeakHashMap, and IdentityHashMap -- each solving one narrow problem a general-purpose HashMap can't.
Learning objectives
- Explain conceptually how a red-black tree stays balanced through rotations and color rules, and why that guarantees O(log n) worst case
- Use NavigableMap operations (floorKey, ceilingKey, headMap, tailMap, subMap) to answer range and nearest-neighbor queries
- Describe at a glance how ConcurrentHashMap achieves high-throughput concurrent access without a single global lock
- Identify when EnumMap, WeakHashMap, or IdentityHashMap is the correct, narrow-purpose choice over a general HashMap
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TreeMap, NavigableMap, and the Specialized Map Family