Rearrange

import java.util.Scanner;
public class Rearrange
{
    static Scanner sc = new Scanner(System.in);
    int a[];
    int n;
    int capacity;
    int pos1;
    int pos2;
    int item;

    void enter()
    {
        // Maximum number of elements that the array
        // can store
        capacity = 1000;
        a = new int[capacity];
        System.out.print("Enter the size of the array: ");
        n = sc.nextInt();

        for(int i = 0; i < n; i++)
        {
            System.out.print("Enter element " + (i + 1) + ": ");
            a[i] = sc.nextInt();
        }
    }

    void insert()
    {
        // Take a valid position as input
        if(n == capacity)
        {
            System.out.println("Array does not have space to insert more elements");
        }
        else
        {
            while(true)
            {
                System.out.println("Valid positions for insertions are");
                System.out.println(0 + " to " + n);
                System.out.print("Enter the position to insert element: ");
                pos1 = sc.nextInt();
                if(pos1 >= 0 && pos1 <= n)
                {
                    break;
                }
                else
                {
                    System.out.println(pos1 + " is an invalid position.");
                }
            }
            System.out.print("Enter the element to be inserted in array: ");
            item = sc.nextInt();
            // Shift all elements from positions
            // pos1 to n-1, one place to the right
            for(int i = n-1; i >= pos1; i--)
            {
                a[i + 1] = a[i];
            }
            // Insert the new element
            a[pos1] = item;
            // Increase the size of the array
            n = n + 1;
            System.out.println(item + " inserted at position " + pos1);
            System.out.println("New contents of the array are");
            disp1();
        }
    }

    void remove()
    {
        if(n == 0)
        {
            System.out.println("Cannot delete from an empty array.");
        }
        else
        {
            while(true)
            {
                System.out.println("Valid positions for insertions are");
                System.out.println(0 + " to " + (n-1));
                System.out.print("Enter the position to delete an element: ");
                pos2 = sc.nextInt();
                if(pos2 >= 0 && pos2 <= (n - 1))
                {
                    break;
                }
                else
                {
                    System.out.println(pos2 + " is an invalid position.");
                }
            }
            // To delete the element at pos2 position,
            // all elements from pos2 + 1 to n-1 must be shifted by
            // one place to the left
            int deletedElement = a[pos2];
            for(int i = pos2 + 1; i < n; i++)
            {
                a[i - 1] = a[i];
            }
            // Decrease size of array
            n = n - 1;
            System.out.println(deletedElement + " deleted from position " + pos2);
            System.out.println("New contents of the array are");
            disp2();
        }
    }

    void disp1()
    {
        for(int i = 0; i < n; i++)
        {
            System.out.print(a[i] + ", ");
        }
        System.out.println("");
    }

    void disp2()
    {
        disp1();
    }

    public static void main(String[] args)
    {
        Rearrange obj = new Rearrange();
        obj.enter();
        int choice;
        do
        {
            System.out.println("---------Menu---------");
            System.out.println("Press 1 for inserting an element in the array");
            System.out.println("Press 2 for deleting an element from the array");
            System.out.println("Press 3 for displaying the contents of the array");
            System.out.println("Press 4 to quit");
            System.out.print("Enter your choice(1-4): ");
            choice = sc.nextInt();

            switch(choice)
            {
                case 1: {
                    obj.insert();
                    break;
                }
                case 2: {
                    obj.remove();
                    break;
                }
                case 3: {
                    obj.disp1();
                    break;
                }
                case 4: {
                    System.out.println("Quitting...");
                    break;
                }
                default: {
                    System.out.println("Invalid choice.");
                }
            }
        }while(choice != 4);
    }
}