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64+ curated questions with the same answer shape every time: quick recap, deep dive, pitfalls, and follow-ups. Coverage includes collections utility methods, comparisons, iterator and foreach, list basics, and more.
Suggested path
Topics follow a teaching order. Each answer ends with a clear Next question control so you can move forward without hunting the list.
Java Collections is one of the top-three most-asked sections in every fresher screening. Interviewers want to know whether you can pick the right data structure — ArrayList vs LinkedList, HashMap vs HashSet, PriorityQueue for heap problems — and whether you understand what's happening under the hood when you call put() or get(). This module covers the framework's core contracts (List, Set, Map, Queue), the implementation trade-offs that freshers are expected to articulate, the equals/hashCode contract that powers every Map and Set, and the iteration patterns that appear in every coding round.
Full catalog
Topics are ordered for learning. Within each topic, rows are numbered 1–64 globally so you always know where you are. Collapse topics if you want a lighter view — use Expand all when you need the full list again.
Numbers 1–64 follow the order we recommend — click any row to open the full answer, or use the sticky Next link at the bottom of each page to go Q1 → Q64.