Question

package datastructure;

public class UseQueue {

   public static void main(String[] args) {
      /*
       * Demonstrate how to use Queue that includes add,peek,remove,pool elements.
       * Use For Each loop and while loop with Iterator to retrieve data.
       * 
       */

   }

}

Answer 1

Source Code:

class arrayQueue
{
    protected int Queue[] ;
    protected int front, rear, size, len;
 
    
    public arrayQueue(int n) 
    {
        size = n;
        len = 0;
        Queue = new int[size];
        front = -1;
        rear = -1;
    }    
    public boolean isEmpty() 
    {
        return front == -1;
    }    
    public boolean isFull() 
    {
        return front==0 && rear == size -1 ;
    }    
    public int getSize()
    {
        return len ;
    }    
    public int peek() 
    {
        if (isEmpty())
           throw new NoSuchElementException("Underflow Exception");
        return Queue[front];
    }   
     public void insert(int i) 
    {
        if (rear == -1) 
        {
            front = 0;
            rear = 0;
            Queue[rear] = i;
        }
        else if (rear + 1 >= size)
            throw new IndexOutOfBoundsException("Overflow Exception");
        else if ( rear + 1 < size)
            Queue[++rear] = i;    
        len++ ;    
    }    
   
    public int remove() 
    {
        if (isEmpty())
           throw new NoSuchElementException("Underflow Exception");
        else 
        {
            len-- ;
            int ele = Queue[front];
            if ( front == rear) 
            {
                front = -1;
                rear = -1;
            }
            else
                front++;                
            return ele;
        }        
    }
    
    public void display()
    {
        System.out.print("\nQueue = ");
        if (len == 0)
        {
            System.out.print("Empty\n");
            return ;
        }
        for (int i = front; i <= rear; i++)
            System.out.print(Queue[i]+" ");
        System.out.println();        
    }
}
 

public class UseQueue
{
    public static void main(String[] args)
    {
        Scanner scan = new Scanner(System.in);
 
        System.out.println("Array Queue Test\n");
        System.out.println("Enter Size of Integer Queue ");
        int n = scan.nextInt();
        /* creating object of class arrayQueue */
        arrayQueue q = new arrayQueue(n);        
        /* Perform Queue Operations */        
        char ch;
        do{
            System.out.println("\nQueue 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. check full");
            System.out.println("6. size");
            int choice = scan.nextInt();
            switch (choice)
            {
            case 1 : 
                System.out.println("Enter integer element to insert");
                try
                {
                    q.insert( scan.nextInt() );
                }
                catch(Exception e)
                {
                    System.out.println("Error : " +e.getMessage());
                }                         
                break;                         
            case 2 : 
                try
                {
                    System.out.println("Removed Element = "+q.remove());
                }
                catch(Exception e)
                {
                    System.out.println("Error : " +e.getMessage());
                }
                break;                         
            case 3 : 
                try
                {
                    System.out.println("Peek Element = "+q.peek());
                }
                catch(Exception e)
                {
                    System.out.println("Error : "+e.getMessage());
                }
                break;                            
            case 4 : 
                System.out.println("Empty status = "+q.isEmpty());
                break;                
            case 5 : 
                System.out.println("Full status = "+q.isFull());
                break;                          
            case 6 : 
                System.out.println("Size = "+ q.getSize());
                break;                         
            default : System.out.println("Wrong Entry \n ");
                break;
            }
            /* display Queue */
            q.display();            
            System.out.println("\nDo you want to continue (Type y or n) \n");
            ch = scan.next().charAt(0);
 
        } while (ch == 'Y'|| ch == 'y');                                                        
    }    
}

Therefore, I've implemented the desired functions and I've used for loop to display the elements of queue.

Let me know if you have any doubts or if you need anything to change. 

If you are satisfied with the solution, please leave a +ve feedback : ) Let me know for any help with any other questions.

Thank You!
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