w3resource

Java: Retrieve and remove the first element of a tree set


14. Poll First TreeSet Element

Write a Java program to retrieve and remove the first element of a tree set.

Sample Solution:

Java Code:

import java.util.TreeSet;
import java.util.Iterator;

  public class Exercise14 {
  public static void main(String[] args) {
 // creating TreeSet 
   TreeSet <Integer>tree_num = new TreeSet<Integer>();
   TreeSet <Integer>treeheadset = new TreeSet<Integer>();
     
   // Add numbers in the tree
   tree_num.add(10);
   tree_num.add(22);
   tree_num.add(36);
   tree_num.add(25);
   tree_num.add(16);
   tree_num.add(70);
   tree_num.add(82);
   tree_num.add(89);
   tree_num.add(14);
   System.out.println("Original tree set: "+tree_num);
   System.out.println("Removes the first(lowest) element: "+tree_num.pollFirst());
   System.out.println("Tree set after removing first element: "+tree_num);
   }    
}

Sample Output:

Original tree set: [10, 14, 16, 22, 25, 36, 70, 82, 89]                
Removes the first(lowest) element: 10                                  
Tree set after removing first element: [14, 16, 22, 25, 36, 70, 82, 89]

Flowchart:

Flowchart: Retrieve and remove the first element of a tree set

For more Practice: Solve these Related Problems:

  • Write a Java program to use pollFirst() on a TreeSet to retrieve and remove the first element, then print the modified set.
  • Write a Java program to implement a method that recursively removes and returns the first element of a TreeSet.
  • Write a Java program to compare the first element before and after removal using pollFirst() and then validate the operation.
  • Write a Java program to use a custom iterator to remove the first element of a TreeSet without using built-in methods.

Go to:


PREV : TreeSet Lower Element.
NEXT : Poll Last TreeSet Element.

Java Code Editor:

Contribute your code and comments through Disqus.

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.



Follow us on Facebook and Twitter for latest update.