collections

lists, sets, maps, queues. what each one actually is in memory, and which to pick.

1. 01the big picturethe interface family tree, from Iterable down to SequencedMap.
2. 02ArrayListan array that grows. how much, when, and what it costs.
3. 03LinkedList and ArrayDequenodes and pointers vs a circular buffer. (spoiler: use the deque.)
4. 04HashMapbuckets, hashes, collisions, resizing. put a key in and watch where it lands.
5. 05LinkedHashMap and LRU cachesa hashmap with a linked list threaded through it.
6. 06TreeMap and sorted mapsa red-black tree that stays balanced while you insert.
7. 07setsHashSet (a HashMap in disguise), TreeSet, and EnumSet (a bit vector).
8. 08PriorityQueuea binary heap in an array. sift up, sift down.
9. 09immutable collectionsList.of, copyOf, and unmodifiable views that aren't actually immutable.
10. 10iterators and fail-fastmodCount and the ConcurrentModificationException you got in a single thread.
11. 11sorting and comparatorsComparable, Comparator.comparing().thenComparing(), and TimSort.
12. 12choosing a collectiona decision tree and a big-O cheat sheet.