int size()

// Java code to illustrate Set.size() method
  
import java.util.*;
  
public class SetDemo {
    public static void main(String args[])
    {
  
        // Creating an empty Set
        SortedSet<String> set
            = new TreeSet<String>();
  
        // Use add() method to
        // add elements into the Set
        set.add("Welcome");
        set.add("To");
        set.add("Geeks");
        set.add("4");
        set.add("Geeks");
  
        // Displaying the Set
        System.out.println("Set: " + set);
  
        // Displaying the size of the Set
        System.out.println(
            "The size of the SortedSet is: "
            + set.size());
    }
}

Set: [4, Geeks, To, Welcome]
The size of the SortedSet is: 4