TreeMap Implemented with Red-Black Tree

The TreeMap class in Java is an ordered Map collection implemented using a red-black tree. It resides in the java.util package and implements the SortedMap interface, allowing sorting based on the natural ordering of keys or a specified comparator.

Key characteristics of the TreeMap class include:

1. Implementation based on Red-Black Tree: The TreeMap class is implemented using a red-black tree, enabling efficient insertion, deletion, and lookup operations.
2. Ordering: Elements within the TreeMap are sorted according to the natural ordering of their keys or a specified comparator, facilitating convenient range queries and sorting operations.
3. Thread-Unsafe: The TreeMap class is not thread-safe; if used in a multi-threaded environment, additional synchronization measures must be implemented.

The TreeMap class provides multiple constructors to create an empty TreeMap object or a TreeMap object with a specified comparator. It also offers various methods for adding, removing, retrieving, and modifying elements, some of which are similar to those in the Map interface.

Key methods of the TreeMap class include:

1. put() method: Adds a key-value pair to the TreeMap object.
2. remove() method: Removes the key-value pair associated with a specified key from the TreeMap object.
3. get() method: Retrieves the value associated with a specified key in the TreeMap object.
4. size() method: Returns the number of key-value mappings in the TreeMap object.
5. clear() method: Removes all key-value mappings from the TreeMap object.

// Example demonstrating basic operations on a TreeMap
import java.util.*;

public class TreeMapExample {
    public static void main(String[] args) {
        // Create an empty TreeMap using default natural ordering
        TreeMap<String, Integer> map = new TreeMap<>();
        
        // Add key-value pairs
        map.put("apple", 1);
        map.put("banana", 2);
        map.put("cherry", 3);
        
        // Retrieve value by key
        Integer val = map.get("banana");
        System.out.println(val); // Output: 2
        
        // Get the size of the map
        System.out.println(map.size()); // Output: 3
        
        // Remove a specific entry
        map.remove("apple");
        
        // Clear all entries
        map.clear();
    }
}