Beginning Java Data Structures and Algorithms

Adding and Deleting the Elements from the Queue

To implement the enqueue() and dequeue() methods in Java, follow these steps:

1. Using a double linked list, implement the dequeue and enqueue pseudocode shown in the preceding code in Java. Follow the structure and method signature shown in the following code snippet:

public class Queue<V> {  private DblLinkedListNode<V> head;  private DblLinkedListNode<V> tail;  public void enqueue(V item)  public Optional<V> dequeue()} 

Snippet 2.20: Exercise class structure and method signatures

2. The enqueue() method can be implemented as shown in the following code:

public void enqueue(V item) {  DblLinkedListNode<V> node = new DblLinkedListNode<>(item, null, tail); Optional.ofNullable(tail).ifPresent(n -> n.setNext(node)); ...