Using NetBeans Implement a queue named QueueLL using a Linke

Using NetBeans

Implement a queue named QueueLL using a Linked List (same as we did for the stack). This implementation must be used in all the following problems.

Implement a queue QueueST using a stack (use StackLL).

Test your implementations in the main with examples.

Solution

Answer:-

import java.util.*;

/* Class Node */
class Node
{
protected int data;
protected Node link;

/* Constructor */
public Node()
{
link = null;
data = 0;
}
/* Constructor */
public Node(int d,Node n)
{
data = d;
link = n;
}
/* Function to set link to next Node */
public void setLink(Node n)
{
link = n;
}
/* Function to set data to current Node */
public void setData(int d)
{
data = d;
}
/* Function to get link to next node */
public Node getLink()
{
return link;
}
/* Function to get data from current Node */
public int getData()
{
return data;
}
}

/* Class linkedQueue */
class linkedQueue
{
protected Node front, rear;
public int size;

/* Constructor */
public linkedQueue()
{
front = null;
rear = null;
size = 0;
}
/* Function to check if queue is empty */
public boolean isEmpty()
{
return front == null;
}
/* Function to get the size of the queue */
public int getSize()
{
return size;
}
/* Function to insert an element to the queue */
public void insert(int data)
{
Node nptr = new Node(data, null);
if (rear == null)
{
front = nptr;
rear = nptr;
}
else
{
rear.setLink(nptr);
rear = rear.getLink();
}
size++ ;
}
/* Function to remove front element from the queue */
public int remove()
{
if (isEmpty() )
throw new NoSuchElementException(\"Underflow Exception\");
Node ptr = front;
front = ptr.getLink();
if (front == null)
rear = null;
size-- ;
return ptr.getData();
}
/* Function to check the front element of the queue */
public int peek()
{
if (isEmpty() )
throw new NoSuchElementException(\"Underflow Exception\");
return front.getData();
}
/* Function to display the status of the queue */
public void display()
{
System.out.print(\"\ Queue = \");
if (size == 0)
{
System.out.print(\"Empty\ \");
return ;
}
Node ptr = front;
while (ptr != rear.getLink() )
{
System.out.print(ptr.getData()+\" \");
ptr = ptr.getLink();
}
System.out.println();
}
}

/* Class LinkedQueueImplement */
public class LinkedQueueImplement
{
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
/* Creating object of class linkedQueue */   
linkedQueue lq = new linkedQueue();
/* Perform Queue Operations */
System.out.println(\"Linked Queue Test\ \");
char ch;
do
{
System.out.println(\"\ Queue Operations\");
System.out.println(\"1. insert\");
System.out.println(\"2. remove\");
System.out.println(\"3. peek\");
System.out.println(\"4. check empty\");
System.out.println(\"5. size\");
int choice = scan.nextInt();
switch (choice)
{
case 1 :
System.out.println(\"Enter integer element to insert\");
lq.insert( scan.nextInt() );
break;   
case 2 :
try
{
System.out.println(\"Removed Element = \"+ lq.remove());
}
catch (Exception e)
{
System.out.println(\"Error : \" + e.getMessage());
}
break;   
case 3 :
try
{
System.out.println(\"Peek Element = \"+ lq.peek());
}
catch (Exception e)
{
System.out.println(\"Error : \" + e.getMessage());
}
break;   
case 4 :
System.out.println(\"Empty status = \"+ lq.isEmpty());
break;

case 5 :
System.out.println(\"Size = \"+ lq.getSize());
break;

default :
System.out.println(\"Wrong Entry \ \");
break;
}
/* display queue */
lq.display();

System.out.println(\"\ Do you want to continue (Type y or n) \ \");
ch = scan.next().charAt(0);
} while (ch == \'Y\'|| ch == \'y\');
}
}