TreeMap in Java

A TreeMap in Java is a part of the java.util package that implements the Map interface. It stores key-value pairs in a sorted order using either a natural or custom comparator.

• TreeMap internally uses a Red-Black Tree for efficient sorting.
• Provides O(log n) time for insertion, deletion and lookup.
• TreeMap does not allow null keys, but allows null values.

import java.util.Map;
import java.util.TreeMap;

public class TreeMapCreation {
    public static void main(String args[]){
        
        // Create a TreeMap of Strings (keys) and Integers
        // (values)
        TreeMap<String, Integer> tm = new TreeMap<>();

        System.out.println("TreeMap elements: " + tm);
    }
}

TreeMap elements: {}

Hierarchy of TreeMap