JAVA Implement a priority queue (priorities will be integers) using a doubly linked list. Assume that the smaller the integer the higher priority. The main operations of the priority queue are:

add (n): inserts priority n. max: returns (but does not delete) the highest priority. removeMax(): removes a highest priority.

Write a tester class and name it Main.

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PRIORITY QUEUE CLASS

public class PriorityQueue {

public class Node {

private int info; private Node next; private Node previous;

public Node() { info = 0; next = null; previous = null; }

public void setInfo(int i) { info = i; }

public void setNext(Node l) { next = l; }

public void setPrevious(Node j) { previous = j; }

public int getInfo() { return info; }

public Node getNext() { return next; }

public Node getPrevious() { return previous; } }

private Node first; private Node last;

public PriorityQueue() { first = new Node(); last = new Node(); first.setNext(last); last.setPrevious(first); }

public boolean isEmpty() { return (first.getNext() == last); }

public void display() { Node current = first.getNext();

while (current != last) { System.out.print(current.getInfo() + " "); current = current.getNext(); }

System.out.println(); }

public void add(int n) { //FILL IN } public int max() { //FILL IN } public void removeMax() { //FILL IN }

public int getLength() {

int length = 0; Node current = first.getNext(); while (current != null) { length++;

current = current.getNext(); } return length; }

}