Runtime
| Map | put | get | containsKey | next | Data Structure |
|---|---|---|---|---|---|
| HashMap | O(1) ~ O(n) | O(1) | O(1) | O(h / n) | Hash Table |
| LinkedHashMap | O(1) ~O(n) | O(1) | O(1) | O(1) | Hash Table + Linked List |
| IdentityHashMap | O(1) ~O(n) | O(1) | O(1) | O(h / n) | Array |
| WeakHashMap | O(1) ~O(n) | O(1) | O(1) | O(h / n) | Hash Table |
| EnumMap | O(1) ~O(n) | O(1) | O(1) | O(1) | Array |
| TreeMap | O(log n) | O(log n) | O(log n) | O(log n) | Red-black tree |
| ConcurrentHashMap | O(1) ~O(n) | O(1) | O(1) | O(h / n) | Hash Tables |
| ConcurrentSkipListMap | O(1) ~O(n) | O(log n) | O(log n) | O(1) | Skip List |