Spiral_Pattern.java

import java.util.Scanner;  

public class Spiral_Pattern  
{  
static void printSpiralPattern(int size)  
{  
//create two variables row and col to traverse rows and columns  
int row = 0, col = 0;  
int boundary = size - 1;  
int sizeLeft = size - 1;  
int flag = 1;  
//variables r, l, u and d are used to determine the movement  
// r = right, l = left, d = down, u = upper  
char move = 'r';  
//creating a 2D array for matrix  
int[][] matrix =new int [size][size];  
for (int i = 1; i < size * size + 1; i++)  
{  
    matrix[row][col] = i;  
//determining the next index  
switch (move)  
{  
//if move = right, go right  
case 'r':  
    col += 1;  
    break;  
//if move = left, go left  
case 'l':  
    col -= 1;  
    break;  
//if move = up, go up  
case 'u':  
    row -= 1;  
    break;  
//if move = down, go down  
case 'd':  
    row += 1;  
    break;  
}  
if (i == boundary)  
    {  
        //adding left size for the next boundary  
        boundary = boundary + sizeLeft;  
        //decreasing the size of left by 1, if 2 rotations have been made  
        if (flag != 2)  
        {  
        flag = 2;  
        }  
        else  
        {  
        flag = 1;  
        sizeLeft -= 1;  
        }  
        //rotating the movement  
        switch (move)  
        {  
        //if move = right, rotate to down  
        case 'r':  
            move = 'd';  
            break;  
        // if move = down, rotate to left  
        case 'd':  
            move = 'l';  
            break;  
        // if move = left, rotate to up  
        case 'l':  
            move = 'u';  
            break;  
        // if move = up, rotate to right  
        case 'u':  
            move = 'r';  
            break;  
        }  
    }  
    }  
 
    for (row = 0; row < size; row++)  
    {  
        for (col = 0; col < size; col++)  
            {  
                int n = matrix[row][col];  
                if(n < 10)  
                    System.out.print(n +" ");  
                else  
                    System.out.print(n +" ");  
            }  
        System.out.println();  
    }  
}  
public static void main(String args[])  
{  
Scanner scanner = new Scanner(System.in);
System.out.println("Enter the size of array: \n");  
int size = scanner.nextInt();
System.out.println("Spiral Matrix or Pattern is: \n");  
printSpiralPattern(size);  
}  
}