Deque in Java with examples
What is java.util.Deque? In this blog, you will learn about Java Deque Interface also its declaration, Constructors, etc. Deque (double-ended queue) is generally pronounced as a deck.
Java Deque Interface
The Deque (double-ended queue) Interface of Java belongs to the Collection framework.
There are methods for inserting and removing elements at both ends of the deque(or deck).
Simultaneously, it implements both stacks and queues. ArrayDeque, LinkedList Classes implements the Deque interface.
Declaration of Deque Interface
public interface Deque<E> extends Queue<E>
Methods of Deque
ArrayDeque Class
This class provides ease of using a deque(or deck) and resizable array also it has no capacity restrictions. Null elements are not allowed. When used as a stack and LinkedList ArrayDeque is faster.
Constructors
ArrayDeque()
ArrayDeque(Collection<? extends E> c)
ArrayDeque(int numElements)
ArrayDeque class declaration
public class ArrayDeque<E> extends AbstractCollection<E> implements Deque<E>, Cloneable, Serializable
Java ArrayDeque with its methods example
public class ExampleArrayDeque { public static void main(String[] args) { //Creating Deque Deque<String> deque = new ArrayDeque<String>(); System.out.println("--- Simple ArrayDeque ---"); //Adding elements deque.add("Naman"); deque.add("Khushi"); deque.add("Kartik"); //Printing elements of deque for (String str : deque) { System.out.println(str); } System.out.println("\n" + "--- After the offerFirst(Anand) ---"); deque.offerFirst("Anand"); for (String str : deque) { System.out.println(str); } System.out.println("\n" + "--- After the offerLast(Ayush) ---"); deque.offerLast("Ayush"); for (String str : deque) { System.out.println(str); } System.out.println("\n" + "--- After the pollFirst() ---"); deque.pollFirst(); for (String str : deque) { System.out.println(str); } System.out.println("\n" + "--- After the pollLast() ---"); deque.pollLast(); for (String str : deque) { System.out.println(str); } System.out.println("\n" + "peekFirst() " + deque.peekFirst()); System.out.println("peekLast() " + deque.peekLast()); } }
Output --- Simple ArrayDeque --- Naman Khushi Kartik --- After the offerFirst(Anand) --- Anand Naman Khushi Kartik --- After the offerLast(Ayush) --- Anand Naman Khushi Kartik Ayush --- After the pollFirst() --- Naman Khushi Kartik Ayush --- After the pollLast() --- Naman Khushi Kartik peekFirst() Naman peekLast() Kartik
That’s enough for a quick overview of java.util.Deque.
Thank you
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