ArrayDeque offerFirst() Method in Java

Last Updated : 10 Dec, 2018

The Java.util.ArrayDeque.offerFirst(Object element) method in Java is used to add a specific element at the front of the Deque. The function is similar to the addFirst() method of ArrayDeque in Java. Syntax:

Array_Deque.offerFirst(Object element)

Parameters: The parameter element is of the type ArrayDeque and refers to the element to be added at the front of the Deque. Return Value: The function returns True if the element is successfully added into the deque else it returns false. Exceptions: The method throws NullPointerException if the passed parameter is NULL. Below programs illustrate the Java.util.ArrayDeque.offerFirst() method: Program 1: Adding String elements into the Deque.

Java

// Java code to illustrate offerFirst()
import java.util.*;

public class ArrayDequeDemo {
    public static void main(String args[])
    {
        // Creating an empty ArrayDeque
        Deque<String> de_que = new ArrayDeque<String>();

        // Use add() method to add elements into the Deque
        de_que.add("Welcome");
        de_que.add("To");
        de_que.add("Geeks");
        de_que.add("4");
        de_que.add("Geeks");

        // Displaying the ArrayDeque
        System.out.println("Initial Deque: " + de_que);

        // Using offerFirst() to add elements
        de_que.offerFirst("World");
        de_que.offerFirst("Hello");

        // Displaying the ArrayDeque
        System.out.println("Final Deque: " + de_que);
    }
}

Output:

Initial Deque: [Welcome, To, Geeks, 4, Geeks]
Final Deque: [Hello, World, Welcome, To, Geeks, 4, Geeks]

Program 2: Adding Integer elements into the Deque.

Java

// Java code to illustrate offerFirst()
import java.util.*;

public class ArrayDequeDemo {
    public static void main(String args[])
    {
        // Creating an empty ArrayDeque
        Deque<Integer> de_que = new ArrayDeque<Integer>();

        // Use add() method to add elements into the Deque
        de_que.add(10);
        de_que.add(15);
        de_que.add(30);
        de_que.add(20);
        de_que.add(5);

        // Displaying the ArrayDeque
        System.out.println("Initial Deque: " + de_que);

        // Using offerFirst() to add elements
        de_que.offerFirst(1658);
        de_que.offerFirst(2458);

        // Displaying the ArrayDeque
        System.out.println("Final Deque: " + de_que);
    }
}

Output:

Initial Deque: [10, 15, 30, 20, 5]
Final Deque: [2458, 1658, 10, 15, 30, 20, 5]

ArrayDeque offerLast() Method in Java

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