Question

Please explain code 1 and code 2 for each lines

code 1

public class MyQueue {

   public static final int DEFAULT_SIZE = 10;

   private Object data[];

   private int index;

code 2

package test;

import java.util.*;

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

/* Constructor */
public Node()
{
link = null;
data = 0;
}
/* Constructor */
public Node(Object 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 Object 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(Object 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 Object 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 Object 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("\nQueue = ");
if (size == 0)
{
System.out.print("Empty\n");
return ;
}
Node ptr = front;
while (ptr != rear.getLink() )
{
System.out.print((String)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\n");
  
lq.insert("java");
lq.insert("python");
lq.insert("html");
lq.insert("CSS");
System.out.println("Removed Element = "+ lq.remove());
  
System.out.println("Peek Element = "+ lq.peek());
System.out.println("Empty status = "+ lq.isEmpty());
  
System.out.println("Size = "+ lq.getSize());
  
/* display queue */
lq.display();

  
}
}

   public MyQueue() {
       data = new Object[DEFAULT_SIZE];
   }

   public MyQueue(int size) {
       data = new Object[size];
   }

   public boolean isEmpty() {
       return index == 0;
   }

public boolean isFull()
{
if(index == data.length - 1)
return true;
else
return false;
}
   public void enqueue(Object obj) throws Exception {
       if (isFull()) {
           throw new Exception("Queue is full. Dequeue some objects");
       }
System.out.print("\nEnqueue: "+(String)obj);
       this.data[index] = obj;
       this.index++;
   }

   public Object dequeue() throws Exception {
       if (isEmpty())
           throw new Exception("Queue is empty");
       Object obj = this.data[0];
       for (int i = 0; i < this.index - 1; i++) {
           data[i] = data[i + 1];
       }
System.out.print("\nDequeue: "+data[index]);
       this.index--;
       return obj;

   }
  
Object peek()
{
if(!isEmpty())
return this.data[0];
return null;
}
  
int getSize()
{
return this.index;
}
  
void print()
{
if(isEmpty())
{
System.out.println("\nEmpty Queue!");
return;
}
System.out.print("\nQueue Data: ");
for(int i=0; i<index; i++)
{
System.out.print(" "+this.data[i]);
}
}
  
}

class test
{
//main driver method
public static void main(String[] args) throws Exception
{
MyQueue queue = new MyQueue();
queue.enqueue("java");
System.out.println(queue.dequeue());

queue.enqueue("python");
queue.enqueue("xml");
queue.enqueue("css");
System.out.println(queue.dequeue());

queue.enqueue("lisp");
  
queue.print();
queue.dequeue();
queue.print();
queue.enqueue("jason");
queue.print();

}
}

Answer 1

code 1

public class MyQueue { //create class MyQueue

public static final int DEFAULT_SIZE = 10; //declare a variable and fix its value to 10

private Object data[]; //create an object array with Object type

private int index; //integer variable declare

code 2

package test;

import java.util.*;

/* Class Node */

class Node

{

protected Object data; //declare variable data of type Object

protected Node link; //declare variable link of type Node class

/* Constructor */

public Node() //default constructor

{

link = null; //assigning values to variables

data = 0;

}

/* Constructor */

public Node(Object d,Node n) //parameterized constructor

{

data = d; //assigning values to variables

link = n;

}

/* Function to set link to next Node */

public void setLink(Node n) //mutator to set link

{

link = n;

}

/* Function to set data to current Node */

public void setData(int d) //mutator to set data

{

data = d;

}

/* Function to get link to next node */

public Node getLink() //Accessor to get link

{

return link;

}

/* Function to get data from current Node */

public Object getData() //Accessor to get data

{

return data;

}

}

/* Class linkedQueue */

class linkedQueue //create class

{

protected Node front, rear; //declare objects of class Node

public int size; //declare size variable

/* Constructor */

public linkedQueue() //default constructor

{

front = null; //initialize variables

rear = null;

size = 0;

}

/* Function to check if queue is empty */

public boolean isEmpty()

{

return front == null; //return either true or false

}

/* Function to get the size of the queue */

public int getSize()

{

return size; //return size

}

/* Function to insert an element to the queue */

public void insert(Object data)

{

Node nptr = new Node(data, null); //create object of class Node and passing values

if (rear == null) //check either its first insertion

{

front = nptr; //assign front and rear to first insertion

rear = nptr;

}

else //otherwise

{

rear.setLink(nptr); //insert at rear

rear = rear.getLink(); //get the link

}

size++ ; //increase the size of queue

}

/* Function to remove front element from the queue */

public Object remove()

{

if (isEmpty() ) //check queue is empty

throw new NoSuchElementException("Underflow Exception");

Node ptr = front; //assign front to ptr

front = ptr.getLink(); //get link of front

if (front == null) // if there is only one element to delete

rear = null; //make rear null

size-- ; //decrease size

return ptr.getData(); //return deleted data

}

/* Function to check the front element of the queue */

public Object peek()

{

if (isEmpty() ) //check queue is empty

throw new NoSuchElementException("Underflow Exception");

return front.getData(); //return front of queue

}

/* Function to display the status of the queue */

public void display()

{

System.out.print("\nQueue = "); //display queue

if (size == 0) //if size is zero

{

System.out.print("Empty\n"); //queue is empty

return ;

}

Node ptr = front; //assign front to ptr

while (ptr != rear.getLink() ) //while link is not null

{

System.out.print((String)ptr.getData()+" "); //display data

ptr = ptr.getLink(); //move to next element

}

System.out.println(); //create a line gap

}

}

/* Class LinkedQueueImplement */

public class LinkedQueueImplement //create a class

{

public static void main(String[] args) //main method

{

Scanner scan = new Scanner(System.in); //Scanner for taking input from user

/* Creating object of class linkedQueue */

linkedQueue lq = new linkedQueue(); // create object

/* Perform Queue Operations */

System.out.println("Linked Queue Test\n"); //display message

lq.insert("java"); //call insert method with string data

lq.insert("python");

lq.insert("html");

lq.insert("CSS");

System.out.println("Removed Element = "+ lq.remove()); //call remove element method from front

System.out.println("Peek Element = "+ lq.peek()); //display front element

System.out.println("Empty status = "+ lq.isEmpty()); //display queue is empty

System.out.println("Size = "+ lq.getSize()); //display size

/* display queue */

lq.display();

}

}

public MyQueue() { //constructor of MyQueue

data = new Object[DEFAULT_SIZE]; //assign value to data

}

public MyQueue(int size) { //parameterized constructor

data = new Object[size]; //assign value to data

}

public boolean isEmpty() { //check queue is empty

return index == 0; //return true or false

}

public boolean isFull() //check queue is full

{

if(index == data.length – 1) //if index is equal to length of data

return true; //return true

else

return false; //return false

}

public void enqueue(Object obj) throws Exception { //insert element in queue

if (isFull()) {

throw new Exception("Queue is full. Dequeue some objects"); //if full then throw exception

}

System.out.print("\nEnqueue: "+(String)obj); //display data

this.data[index] = obj; //assign value

this.index++; // increase index

}

public Object dequeue() throws Exception { //delete element from queue

if (isEmpty())

throw new Exception("Queue is empty"); //throw exception

Object obj = this.data[0]; //remove element from front

for (int i = 0; i < this.index - 1; i++) {

data[i] = data[i + 1]; //shifting elements a position ahead

}

System.out.print("\nDequeue: "+data[index]); //display deleted element

this.index--; //decrease size

return obj;

}

Object peek() //get front of queue

{

if(!isEmpty()) //check queue is not empty

return this.data[0]; //return front element

return null; //return link null

}

int getSize() //get size

{

return this.index; //return size

}

void print() //display queue

{

if(isEmpty()) //check is empty

{

System.out.println("\nEmpty Queue!"); //display queue is empty

return;

}

System.out.print("\nQueue Data: "); //display message

for(int i=0; i<index; i++) //loop to display values

{

System.out.print(" "+this.data[i]); //display data

}

}

}

class test //test class

{

//main driver method

public static void main(String[] args) throws Exception //main method which can throw exception

{

MyQueue queue = new MyQueue(); //create pbject

queue.enqueue("java"); //insert data

System.out.println(queue.dequeue()); //delete data and display it

queue.enqueue("python"); //insert data

queue.enqueue("xml");

queue.enqueue("css");

System.out.println(queue.dequeue()); //delete data and display it

queue.enqueue("lisp"); //insert data

queue.print(); //print queue

queue.dequeue(); //remove element from queue

queue.print(); //print queue

queue.enqueue("jason"); //insert queue

queue.print(); //print queue

}

}