ArrayDeque removeFirst() Method in Java

Last Updated : 10 Dec, 2018

The Java.util.ArrayDeque.removeFirst() method is used to remove the first element of the Deque. Syntax:

Array_Deque.removeFirst()

Parameters: The method does not take any parameters. Return Value: This method returns the first element of the Deque after removing it. Exceptions: The method throws NoSuchElementException is thrown if the deque is empty. Below programs illustrate the Java.util.ArrayDeque.removeFirst() method: Program 1:

Java

// Java code to illustrate removeFirst()
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("For");
        de_que.add("Geeks");

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

        // Removing elements using removeFirst() method
        de_que.removeFirst();
        de_que.removeFirst();
        de_que.removeFirst();

        // Displaying the ArrayDeque after removal
        System.out.println("ArrayDeque after removing "
                           + "elements: " + de_que);
    }
}

Output:

Initial ArrayDeque: [Welcome, To, Geeks, For, Geeks]
ArrayDeque after removing elements: [For, Geeks]

Program 2:

Java

// Java code to illustrate removeFirst()
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 ArrayDeque: " + de_que);

        // Removing elements using removeFirst() method
        de_que.removeFirst();
        de_que.removeFirst();

        // Displaying the ArrayDeque after removal
        System.out.println("ArrayDeque after removing "
                           + "elements: " + de_que);
    }
}

Output:

Initial ArrayDeque: [10, 15, 30, 20, 5]
ArrayDeque after removing elements: [30, 20, 5]

ArrayDeque removeLast() Method in Java

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