TreeSet pollFirst() method in java

Let’s learn TreeSet pollFirst() method in java.

TreeSet pollFirst() method in java

pollFirst() method retrieves and removes the first (lowest) element, or returns null if this set is empty.

Syntax

public E pollFirst()

Example

import java.util.*;

class TreeSetPollFirstDemo 
{
   public static void main(String[] args) 
   {
      TreeSet<Integer> ts = new TreeSet<Integer>();  
      ts.add(1);     
      ts.add(3);  
      ts.add(6);  
      ts.add(15);  
      ts.add(24);  
      System.out.println("TreeSet before pollFirst() method : " + ts);  
      ts.pollFirst();  
      System.out.println("After removing element from TreeSet : " + ts);  
   }
}

Output:

TreeSet before pollFirst() method : [1, 3, 6, 15, 24]
After removing element from TreeSet : [3, 6, 15, 24]

import java.util.*;

class TreeSetPollFirstDemo 
{
   public static void main(String[] args) 
   {
      TreeSet<String> ts = new TreeSet<String>();  
      ts.add("hello");     
      ts.add("world");  
      ts.add("core");  
      ts.add("java");  
      ts.add("programming");  
      System.out.println("TreeSet before pollFirst() method : " + ts);  
      ts.pollFirst();  
      System.out.println("After removing element from TreeSet : " + ts);  
   }
}

Output:

TreeSet before pollFirst() method : [core, hello, java, programming, world]
After removing element from TreeSet : [hello, java, programming, world]