What is the Difference Between TreeSet and HashSet?
🆚 Go to Comparative Table 🆚The main differences between TreeSet and HashSet in Java are as follows:
- Implementation:
- HashSet is backed by a HashMap, which uses a hash table for storing elements.
- TreeSet is backed by a TreeMap, which uses a tree structure (specifically, a Red-Black tree) for storing elements.
- Performance:
- HashSet is generally faster for operations like search, insert, and delete, taking constant time on average.
- TreeSet takes O(Log n) time for search, insert, and delete operations, which is higher than HashSet.
- Sorted Order:
- HashSet does not support any order.
- TreeSet keeps sorted data and supports operations like higher(), floor(), ceiling(), etc., which are O(Log n).
- Null Elements:
- HashSet allows null elements.
- TreeSet does not allow null elements.
- Comparison Method:
- For HashSet, the equals method is used to compare two objects.
- For TreeSet, the compare method is used to compare two objects.
In summary, HashSet is faster and allows null elements, but it does not maintain a sorted order. On the other hand, TreeSet is slower but maintains a sorted order and does not allow null elements. If you need elements in sorted order, use TreeSet; otherwise, use HashSet for better performance.
On this pageWhat is the Difference Between TreeSet and HashSet? Comparative Table: TreeSet vs HashSet
Comparative Table: TreeSet vs HashSet
Here is a table comparing the differences between TreeSet and HashSet:
| Feature | TreeSet | HashSet |
|---|---|---|
| Performance | Slower (O(Log n) for search, insert, and delete) | Faster (constant time for search, insert, and delete) |
| Internal Data Structure | Red-Black Tree | Hash Table |
| Ordering | Sorted (uses compareTo() method) | Unsorted (uses equals() method for duplicate detection) |
| Duplicate Detection | Compares using compareTo() method | Compares using equals() method |
| Methods | Supports additional methods like higher(), floor(), ceiling() | Does not support these methods |
In summary, use TreeSet if you need a sorted collection and be willing to trade off some performance. On the other hand, use HashSet if you want a faster collection and do not require sorting.
Read more:
- TreeSet vs TreeMap
- HashMap vs TreeMap
- List vs Set
- Hashtable vs Hashmap
- Dictionary vs Hashtable
- equals vs hashCode in Java
- Binary Tree vs Binary Search Tree
- Stack vs Heap
- ArrayList vs LinkedList
- Subset vs Superset
- Arraylist vs Vector
- Tree vs Graph in Data Structure
- Stack vs Queue
- Graph vs Tree
- Memcached vs Redis
- Enumeration vs Iterator
- StringBuffer vs StringBuilder
- Inheritance vs Interface in Java
- Hash vs Weed