import java.util.Scanner;
import java.util.Random;

public class MyArray
{
    public static final int SIZE = 4;
    private int [][] grid;

    public MyArray()
    {
        grid = new int[SIZE][SIZE];
        for (int r = 0; r < SIZE; r++)
        {
            for (int c = 0; c < SIZE; c++)
            {
                grid[r][c] = 0;
            }
        }
    }

    public void display()
    {
        // Calling isNotNull
        if (isNotNull() == true)
        {
            for (int r = 0; r < SIZE; r++)
            {
                for (int c = 0; c < SIZE; c++)
                {
                    System.out.print(grid[r][c]);
                }
                System.out.println();
            }
        }
        else
            System.out.println("Can't display non-existant array");
    }

    // returns true if grid reference is not equal to null 
    // array doesn't exist, false otherwise
    // isNotNull







    // returns true if the row,column outside of the array bounds
    // false otherwise
    outBounds()

















    public void start()
    {
         final int MAX = 9;
         Scanner in = null;
         Random aGenerator = null;
         int row = -1;
         int column = -1;
         display();
         in = new Scanner(System.in);
         aGenerator = new Random();
         System.out.print("Enter row to edit: ");
         row = in.nextInt();
         System.out.print("Enter column to edit: ");
         column = in.nextInt();

         // Calling isNotNull
         if (isNotNull() == true)
         {
             // Calling outBounds
             if (outBounds(row,column) == true)
                System.out.println("Cannot edit outside of grid");
             else
                grid[row][column] = aGenerator.nextInt(MAX)+1;
         }
         else
              System.out.println("Can't edit non-existant array");
         display();  
    }
}