TreeSet iterator() Method in Java

TreeSet isEmpty() Method in Java

Last Updated : 26 Nov, 2018

The Java.util.TreeSet.isEmpty() method is used to check and verify if a TreeSet is empty or not. It returns True if the TreeSet is empty else it returns False. Syntax:

Tree_Set.isEmpty()

Parameters: The method does not take any parameter Return Value: The function returns True if the set is empty else it returns False. Below program illustrate the use of Java.util.TreeSet.isEmpty() method:

Java

// Java code to illustrate isEmpty() method
import java.util.*;
import java.util.TreeSet;

public class TreeSetDemo {
    public static void main(String args[])
    {
        // Creating an empty HashSet
        TreeSet<String> tree = new TreeSet<String>();

        // Use add() method to add elements into the Set
        tree.add("Welcome");
        tree.add("To");
        tree.add("Geeks");
        tree.add("4");
        tree.add("Geeks");
        tree.add("TreeSet");

        // Displaying the TreeSet
        System.out.println("TreeSet: " + tree);

        // Check for the empty set
        System.out.println("Is the set empty? " + tree.isEmpty());

        // Clearing the set using clear() method
        tree.clear();

        // Again Checking for the empty set
        System.out.println("Is the set empty? " + tree.isEmpty());
    }
}

Output:

TreeSet: [4, Geeks, To, TreeSet, Welcome]
Is the set empty? false
Is the set empty? true

TreeSet iterator() Method in Java

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