Can you list different implementations of the Map interface you have worked with?

In Java, the Map interface has several popular implementations that are commonly used:

• HashMap — the most common implementation based on a hash table. Provides fast access by key (average O(1)), does not guarantee element order.

• LinkedHashMap — extends HashMap but maintains insertion order, which is useful if traversal order matters.

• TreeMap — implements the SortedMap interface, stores elements in sorted order by key, based on a red-black tree. Access and insertion operate in O(log n).

• ConcurrentHashMap — thread-safe implementation for concurrent access without locking the entire map.

Example of using HashMap:

Map<String, Integer> map = new HashMap<>();
map.put("apple", 3);
map.put("banana", 5);
int count = map.get("apple");

Each implementation is suitable for different tasks depending on requirements for order, performance, and thread safety.