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Java ArrayDeque peekFirst() Method with Example

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

ArrayDeque Class peekFirst() method

• peekFirst() Method is available in java.lang package.
• peekFirst() Method is used to return the first element of the queue denoted by this deque but without removing the element.
• peekFirst() 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.
• peekFirst() Method does not throw an exception at the time retrieving the first element of this deque.

Syntax:

    public T peekFirst();

Parameter(s):

• It does not accept any parameter.

Return value:

The return type of the method is T, it returns the first element denoted by this deque otherwise it returns null, when this deque is "blank".

Example:

// Java program to demonstrate the example 
// of T peekFirst() method of ArrayDeque 

import java.util.*;

public class PeekFirstOfArrayDeque {
    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: ");
        System.out.println("ArrayDeque Elements = " + d_queue);

        System.out.println();

        // By using peekFirst() method to return the
        // element at the first position in ArrayDeque

        String ele = d_queue.peekFirst();

        // Display Returned Elements
        System.out.println("d_queue.peekFirst() : " + ele);
    }
}

Output

d_queue: 
ArrayDeque Elements = [C, C++, Java, Php, DotNet]

d_queue.peekFirst() : C