TreeMap size() Method in Java with Examples

size() method of TreeMap class is used to get the size of the map which refers to the number of the key-value pair or mappings in the Map.

--> java.util package
    --> TreeMap class
        --> size() Method   

Syntax:

Tree_Map.size()

Return Value: The size of the map which also means the number of key-value pairs present in the map. 

Example 1: Mapping String Values to Integer Keys

Java

// Java Program to Illustrate size() Method
// of TreeMap class

// Importing required classes
import java.util.*;

// Main class
public class GFG {

    // Main driver method
    public static void main(String[] args)
    {
        // Creating an empty TreeMap by
        // declaring object of Integer, string pairs
        TreeMap<Integer, String> tree_map
            = new TreeMap<Integer, String>();

        // Mapping string values to int keys
        // using put() method
        tree_map.put(10, "Geeks");
        tree_map.put(15, "4");
        tree_map.put(20, "Geeks");
        tree_map.put(25, "Welcomes");
        tree_map.put(30, "You");

        // Displaying the elements of TreeMap
        System.out.println("Initial Mappings are: "
                           + tree_map);

        // Now displaying the size of this map
        // using size() method
        System.out.println("The size of the map is "
                           + tree_map.size());
    }
}

Output:

Initial Mappings are: {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}
The size of the map is 5

Example 2: Mapping Integer Values to String Keys

Java

// Java Program to Illustrate the size() method
// of TreeMap class

// Importing required classes
import java.util.*;

// Main class
public class GFG {

    // Main driver method
    public static void main(String[] args)
    {
        // Creating an empty TreeMap by
        // declaring object of string, integer pairs
        TreeMap<String, Integer> tree_map
            = new TreeMap<String, Integer>();

        // Mapping int values to string keys
        // using put() method
        tree_map.put("Geeks", 10);
        tree_map.put("4", 15);
        tree_map.put("Geeks", 20);
        tree_map.put("Welcomes", 25);
        tree_map.put("You", 30);

        // Printing the elements of TreeMap
        System.out.println("Initial Mappings are: "
                           + tree_map);

        // Printing the size of the map
        // using size() method
        System.out.println("The size of the map is "
                           + tree_map.size());
    }
}

Output:

Initial Mappings are: {4=15, Geeks=20, Welcomes=25, You=30}
The size of the map is 4

Note: The same operation can be performed with any type of Mappings with variation and combination of different data types.