Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog.

[1.3.0] - 2026-09-20

V remove(K key) - removes an entry and returns its live value (or null if absent/expired). Not counted as a hit or miss.
V computeIfAbsent(K key, Function<? super K, ? extends V> loader) and an overload taking an explicit long ttlMillis - returns the cached value or computes, stores and returns it. Runs under the cache lock, so concurrent callers for the same key run the loader once. Counts as one hit or miss. A null result or an exception stores nothing.
List<K> keys() - snapshot of live keys, least- to most-recently-used, with no effect on recency or statistics.

Cache hit/miss statistics on LruCache:
- long hitCount() - lifetime count of get() calls that found a live, non-expired entry.
- long missCount() - lifetime count of get() calls that found nothing (key absent, or present but TTL-expired).
- double hitRate() - hitCount / (hitCount + missCount), returning 0.0 before the first get() call to avoid dividing by zero.
- Following Guava's CacheStats convention, these counters are cumulative for the life of the cache instance and are not reset by put() or clear().
New README "Cache Statistics" section with a runnable example, plus a second ## Usage example (a cache-in-front-of-a-lookup pattern).
New hand-calculated test (testHitAndMissCountsWithExactExpectedValues) that walks a specific sequence of puts and gets - including a capacity-triggered eviction and a post-clear() get - and asserts exact expected hitCount(), missCount(), and hitRate() values.

Test coverage for documented-but-untested LruCache edge cases:
- The constructor rejects a capacity less than 1 (0 and negative values) with IllegalArgumentException.
- size() is confirmed to count an expired-but-not-yet-purged entry (purging only happens lazily inside get()), matching the documented contract.
- Re-putting an already-present key does not grow the cache past capacity or evict any other entry.

No behavioral changes were needed — all new edge-case tests passed against the existing implementation.