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Java TreeSet pollFirst() Method with Example

TreeSet Class pollFirst() method: Here, we are going to learn about the pollFirst() method of TreeSet Class with its syntax and example.
Submitted by Preeti Jain, on February 20, 2020

TreeSet Class pollFirst() method

  • pollFirst() method is available in java.util package.
  • pollFirst() method is used to return the first least element and then remove the first element from this TreeSet.
  • pollFirst() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.


    public Element pollFirst();


  • It does not accept any parameter.

Return value:

The return type of the method is Element, it returns the beginning or first element in this TreeSet otherwise it returns null when this TreeSet holds "none" elements.


// Java program to demonstrate the example 
// of Element pollFirst() method of TreeSet 

import java.util.*;

public class PollFirstOfTreeSet {
    public static void main(String[] args) {
        // Instantiates a TreeSet object
        TreeSet < String > tree_set = new TreeSet < String > ();

        // By using add() method is to add
        // the given object of this TreeSet 

        // Display TreeSet
        System.out.println("TreeSet: " + tree_set);

        // By using pollFirst() method is to return
        // the first lowest element and then remove
        // the element exists from this TreeSet
        Object first_lowest = tree_set.pollFirst();

        // Display first_lowest
        System.out.println("tree_set.pollFirst(): " + first_lowest);

        // Display Modified TreeSet
        System.out.println("Modified TreeSet: " + tree_set);


TreeSet: [C, C++, JAVA, PHP, SFDC]
tree_set.pollFirst(): C
Modified TreeSet: [C++, JAVA, PHP, SFDC]

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