Java Deque pollFirst() Method

The pollFirst() method of Java Deque Interface is used to retrieve and remove the first element of the deque. The method may return null if the given deque is empty.

Syntax:

Parameter:

Return:

The above method is used to return the head of the deque. On the other hand, if the deque is empty, the method may return null.

Example 1

import java.util.ArrayDeque;
import java.util.Deque;
public class JavaDequepollFirstExample1 {
   public static void main(String[] args) {
	   Deque<Character> deque = new ArrayDeque<>();
		deque.offer('q');
		deque.offer('u');
		deque.offer('e');
		deque.offer('r');
		deque.offer('y');
		Character val = deque.pollFirst();			
	System.out.println("The first character is given as : "+val);
	System.out.println("The remaining deque is : ");
		for (Character character : deque) {
			System.out.println(character);
		}   	
	}
}

Test it Now

Output:

The first character is given as : q
The remaining deque is : 
u
e
r
y

Example 2

import java.util.ArrayDeque;
import java.util.Deque;
public class JavaDequepollFirstExample2 {
   public static void main(String[] args) {
	   Deque<String> deque = new ArrayDeque<>();
		deque.offer("Hello");
		deque.offer(" ");
		deque.offer("World");
		String val = deque.pollFirst();
		System.out.println("The first string is given as : "+val);
		System.out.println("The remaining deque is : "+deque);
	}
}

Test it Now

Output:

The first string is given as : Hello
The remaining deque is : [ , World]

Example 3

import java.util.ArrayDeque;
import java.util.Deque;
public class JavaDequepollFirstExample3 {
   public static void main(String[] args) {
	 Deque<Long> deque = new ArrayDeque<>();
	    deque.offer(88l);
	    deque.offer(78l);
	    deque.offer(67l);
	   Long val = deque.peek();
	System.out.println("The first long value is given as : "+val);
	System.out.println("The resultant deque is : "+deque);  
   }

Test it Now

Output:

The first long value is given as : 88
The resultant deque is : [88, 78, 67]

Next TopicJava Deque

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