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Java ArrayDeque offerFirst() Method with Example

ArrayDeque Class offerFirst() method: Here, we are going to learn about the offerFirst() method of ArrayDeque Class with its syntax and example.
Submitted by Preeti Jain, on January 10, 2020

ArrayDeque Class offerFirst() method

• offerFirst() Method is available in java.lang package.
• offerFirst() Method is used to add the given element at the front of this deque.
• offerFirst() 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.
• offerFirst() Method may throw an exception at the time of adding element in the deque.
  NullPointerException: This exception may throw when the given element is null exists.

Syntax:

    public boolean offerFirst(T element);

Parameter(s):

• T element – represents the element to be inserted at the first position of this deque.

Return value:

The return type of the method is boolean, it returns true if the given element is added at the front of this deque successfully, else it returns false.

Example:

// Java program to demonstrate the example 
// of boolean offerFirst(T element) method of ArrayDeque 

import java.util.*;

public class OfferFirstOfArrayDeque {
public static void main(String[] args) {
// Creating an ArrayDeque with initial capacity of
// storing elements
Deque<String> d_queue = new ArrayDeque<String>(10);

// By using add() method to add elements
// in ArrayDeque
d_queue.add("C");
d_queue.add("C++");
d_queue.add("Java");
d_queue.add("Php");
d_queue.add("DotNet");

// Display Deque Elements
System.out.println("d_queue before offerFirst(): ");
System.out.println("ArrayDeque Elements = " + d_queue);

System.out.println();

// By using offerFirst() method to add the
// elements at the first position in ArrayDeque

d_queue.offerFirst("Python");

// Display Deque Elements
System.out.println("d_queue after offerFirst(): ");
System.out.println("d_queue.offerFirst() : "+ d_queue);
}
}

Output

d_queue before offerFirst(): 
ArrayDeque Elements = [C, C++, Java, Php, DotNet]

d_queue after offerFirst(): 
d_queue.offerFirst() : [Python, C, C++, Java, Php, DotNet]