In Java, the Set interface provides several implementations to store unique elements. Here's a breakdown of the most common ones:
1. HashSet 📦
- Unordered: Elements are not stored in any specific order.
- Fast Lookup: Uses a hash table for O(1) average time complexity for add/remove operations.
- Duplicates Not Allowed: Automatically handles hash collisions to ensure uniqueness.
👉 Learn more about Java Collections Framework for deeper insights.
2. TreeSet 📊
- Sorted: Elements are stored in a sorted order (natural ordering or custom comparator).
- Balanced Tree: Based on a Red-Black Tree for O(log n) time complexity for search and insertion.
- No Duplicates: Enforces uniqueness through comparison logic.
3. LinkedHashSet 🧾
- Ordered by Insertion: Maintains insertion order while ensuring uniqueness.
- Combines Features: Offers performance similar to HashSet with predictable iteration order.
- Use Case: Ideal for scenarios requiring both uniqueness and order preservation.
4. ConcurrentSkipListSet 🔄
- Thread-Safe: Designed for concurrent environments with lock-free operations.
- Sorted & Balanced: Uses a skip list structure for efficient sorted access.
- Advanced Use: Suitable for high-concurrency applications requiring sorted data.
For visual comparisons of these implementations, check out our Java Collections Diagrams page! 📈