Priority Queue Using Linked List (Custom Implementation)

package com.vzt.Test.PQ;

public class PQUsingLL {

public static void main(String[] vj) {

PriorityQ obj = new PriorityQ();

System.out.println("INSERTING...");

obj.enqueue("A",1);

obj.enqueue("B",2);

obj.enqueue("C",3);

obj.enqueue("D",4);

obj.displayList();

System.out.println("REMOVING...");

obj.dequeue();

obj.dequeue();

obj.dequeue();

obj.dequeue();

}

}

class PriorityQ {

    private LinkList list;

    public PriorityQ() {

        list = new LinkList();

    }

    public void enqueue(String x, int p) {

        list.insert(x, p);

    }

    public void dequeue() {

        list.remove();

    }

    public void displayList() {

        System.out.println("PRINTING...");

        list.display();

    }

}

class LinkList {

    private OneNode first;

    public LinkList() {

        first = null;

    }

    public boolean isEmpty() {

        return (first == null);

    }

    public void insert(String x, int p) {

    OneNode newNode = new OneNode(x, p);

    OneNode previous = null;

    OneNode current = first;

        while (current != null && p > current.priority) {

            previous = current;

            current = current.next;

        }

        if (previous == null) {

            newNode.next = first;

            first = newNode;

        }

        else {

            previous.next = newNode;

            newNode.next = current;

        }

    }

    public OneNode remove() {

    if(null == first) {

    return null;

    }

    OneNode temp = first;

    first = first.next;

    temp.displayNode();

        return temp;

    }

    public void display() {

    OneNode current = first;

        while (current != null) {

            current.displayNode();

            current = current.next;

        }

        System.out.println(" ");

    }

public String peek() {

return first.info;

}

}

class OneNode {

    String info;

    int priority;

    OneNode next;

    public OneNode(String x, int p) {

    info = x;

    priority = p;

    next = null;

    }

    public void displayNode() {

        System.out.println("Data = " + info);

    }

}