Java ArrayDeque Class: offerFirst() Method

public boolean offerFirst(E e)

The offerFirst() method is used to insert an element at the front of a given deque.

Package: java.util

Java Platform: Java SE 8

Syntax:

offerFirst(E e)

Parameters:

Return Value:

true (as specified by Deque.offerFirst(E))

Return Value Type: boolean

Throws:

NullPointerException - if the specified element is null

Pictorial Presentation

Example: Java ArrayDeque Class: offerFirst() Method

import java.util.ArrayDeque;
import java.util.Deque;

public class Main {
   public static void main(String[] args) {
      
      // Create an empty array deque 
      Deque<Integer> deque = new ArrayDeque<Integer>(8);

      // Use add() method to add elements in the deque
      deque.add(20);
      deque.add(30);
      deque.add(40);
      deque.add(35);        
      
      // Print all the elements of the original deque
      System.out.println("Elements of the original deque:");
      for (Integer n : deque) {
         System.out.println(n);
      }

      // Insert 50 at the end of the deque using offer() method.
      deque.offerFirst(50);

      // Print all the elements available in deque
      System.out.println("Elements of the deque after insert an element at the first position of the deque:");
      for (Integer n : deque) {
         System.out.println(n);
      }
   }
}

Output:

Elements of the original deque:
20
30
40
35
Elements of the deque after insert an element at the first position of the deque:
50
20
30
40
35

Java Code Editor:

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