How to Create TreeMap in Java?

The TreeMap in Java is used to implement Map interface and NavigableMap along with the Abstract Class. The map is sorted according to the natural ordering of its keys, or by a Comparator provided at map creation time, depending on which constructor is used.

To create TreeMap we can use Map class or TreeMap class reference.

Example 1:

Java

// Java program demonstrate how to create a TreeMap

import java.util.*;

class GFG {

    public static void main(String[] args)
    {
        // Declaring a treemap
        TreeMap<Integer, String> map;

        // Creating an empty TreeMap
        map = new TreeMap<Integer, String>();

        System.out.println("TreeMap successfully"
                           + " created");
    }
}

Output

TreeMap successfully created

Example 2:

Java

// Java program demonstrate how to create and add elements
// to TreeMap

import java.util.*;

class GFG {
    public static void main(String[] args)
    {
        // Creating an empty TreeMap using Map interface
        Map<Integer, String> map = new TreeMap<>();

        System.out.println("TreeMap successfully"
                           + " created");

        // Adding elements
        map.put(1, "Geeks");
        map.put(2, "for");
        map.put(3, "Geeks");

        // Printing TreeMap
        System.out.println("TreeMap: " + map);
    }
}

Output

TreeMap successfully created
TreeMap: {1=Geeks, 2=for, 3=Geeks}