Queue_LinkedList.java

package DATA_STRUCTURE;

public class Queue_LinkedList {
    class Node{
        int data;
        Node next;
        Node(int d){
            this.data = d;
        }
    }
    Node front = null;
    Node rear = null;

    void insert(int d){
        Node n = new Node(d);
        n.next = null;
        if (front == null) {
            front = rear = n;
            System.out.println(n.data+" is Inserted ");
        }
        else{
            rear.next = n;
            rear = n;
            System.out.println(n.data+" is Inserted ");
        }
    }
    void delete(){
        if (front == null){
            System.out.println("Underflow");
        }
        else{
            System.out.println(front.data+" is deleted form Queue");
            front = front.next;
        }
    }
    void display(){
        Node n = front;
        if(n == null){
            System.out.println("Queue is empty..!");
            return;
        }
        while(n!=null){
            System.out.print(n.data+" ");
            n = n.next;
        }
    }
    int count(){
        Node n = front;
        int p =0;

        while(n!=null){
            p++;
            n = n.next;
        }
        return p;
    }
    public static void main(String[] args) {
        Queue_LinkedList q = new Queue_LinkedList();
        q.insert(1);
        q.insert(11);
        q.insert(12);
        q.insert(123);
        q.insert(1234);
        q.delete();
        q.display();
        System.out.println("total number of nodes : "+q.count());
    }
}