How to Create TreeMap in Java?

Last Updated : 07 Jan, 2021

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}

Suggest improvement

How to Copy Key-Value Pairs from One TreeMap to Another in Java?

Java Program to Implement ArrayList API

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