intermediate~4h
Iterators, Fail-Fast Traversal, and the Collections/Arrays Utility Belt
How Iterator and ListIterator actually traverse a collection, why fail-fast iteration throws ConcurrentModificationException instead of silently misbehaving, the fail-safe alternatives that avoid it, and the Collections/Arrays utility classes plus the modern unmodifiable-vs-immutable distinction.
Learning objectives
- Explain how Iterator and ListIterator traverse a collection and what ListIterator adds for bidirectional, in-place modification
- Explain the mechanism behind fail-fast iteration and exactly which operations trigger ConcurrentModificationException
- Name and use the fail-safe alternatives (CopyOnWriteArrayList, ConcurrentHashMap's weakly consistent iterators, Iterator.remove, removeIf)
- Use the key static methods on Collections and Arrays confidently (sort, binarySearch, unmodifiableList, emptyList, Arrays.asList pitfalls)
- Distinguish an unmodifiable view from a genuinely immutable collection, including what List.of() and similar factory methods actually guarantee
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Iterators, Fail-Fast Traversal, and the Collections/Arrays Utility Belt