Java Program to Print Spiral Pattern

Spiral Pattern Java Program

SpiralPaternExample1.java

public class SpiralPatternExample1  
{  
//defining method to print the spiral pattern or matrix  
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++)  
{  
    //assigning values  
    matrix[row][col] = i;  
//switch-case to determine the next index  
switch (move)  
{  
//if right, go right  
case 'r':  
    col += 1;  
    break;  
//if left, go left  
case 'l':  
    col -= 1;  
    break;  
//if up, go up  
case 'u':  
    row -= 1;  
    break;  
//if down, go down  
case 'd':  
    row += 1;  
    break;  
}  
//checks if the matrix has reached the array boundary  
if (i == boundary)  
    {  
        //adds the left size for the next boundary  
        boundary = boundary + sizeLeft;  
        //decrease the size left by 1, if 2 rotations have been made  
        if (flag != 2)  
        {  
        flag = 2;  
        }  
        else  
        {  
        flag = 1;  
        sizeLeft -= 1;  
        }  
        //switch-case to rotate the movement  
        switch (move)  
        {  
        //if right, rotate to down  
        case 'r':  
            move = 'd';  
            break;  
        // if down, rotate to left  
        case 'd':  
            move = 'l';  
            break;  
        // if left, rotate to up  
        case 'l':  
            move = 'u';  
            break;  
        // if up, rotate to right  
        case 'u':  
            move = 'r';  
            break;  
        }  
    }  
    }  
//printing the spiral matrix or pattern  
//outer for loop for rows  
    for (row = 0; row < size; row++)  
    {  
        //inner for loop for columns  
        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();  
    }  
}  
//driver Code  
public static void main(String args[])  
{  
//size of the array?s row and column  
int size = 5;  
System.out.println("Spiral Matrix or Pattern is: \n");  
//calling the method that prints the spiral pattern or matrix   
printSpiralPattern(size);  
}  
}  

Output:

Let's see another spiral pattern.

In the following program, we have used the following approach:

Starting the indexing from i = 1 and j = 1. It can be observed that every value of the required matrix will be max(abs(i - n), abs(j - n)) + 1.

SpiralPatternExample2.java

import java.util.Scanner;  
import java.lang.Math;  
public class SpiralPatternExample2  
{  
//function to print the spiral pattern  
public static void printPattern(int n)  
{  
//detrmines the boundary size of the array  
int size = 2 * n - 1;  
//inner loop  
for(int i = 1; i <= size; i++)  
{  
//outer loop      
for(int j = 1; j <= size; j++)  
{  
//calculates and prints the values for pattern  
System.out.print(Math.max(Math.abs(i - n), Math.abs(j - n)) + 1 + " ");  
}  
System.out.println();  
}  
}  
//driver code  
public static void main(String args[])  
{  
Scanner sc = new Scanner(System.in);  
System.out.print("Enter the value of n: ");  
int n = sc.nextInt();  
System.out.println();  
//function calling  
printPattern(n);  
}  
}  

Output:

SpiralPatternExample3.java

public class SprialPatternExample3  
{  
public static void main(String args[])  
{  
    int SIZE=10;  
    int i, j, N;  
    int[][] board = new int[SIZE][SIZE];  
    int left, top;  
    left = 0;  
    top  = SIZE - 1;  
    N    = 1;  
    for(i=1; i<=SIZE/2; i++, left++, top--)  
    {  
        //fill from left to right  
        for(j=left; j<=top; j++, N++)  
        {  
            board[left][j] = N;  
        }  
        //fill from top to down  
        for(j=left+1; j<=top; j++, N++)  
        {  
            board[j][top] = N;  
        }  
        //fill from right to left  
        for(j=top-1; j>=left; j--, N++)  
        {  
            board[top][j] = N;  
        }  
        //fill from down to top  
        for(j=top-1; j>=left+1; j--, N++)  
        {  
            board[j][left] = N;  
        }  
    }  
    //print the pattern  
    for(i=0; i<SIZE; i++)  
    {  
        for(j=0; j<SIZE; j++)  
        {  
            System.out.printf("%-5d", board[i][j]);  
        }  
    System.out.printf("\n");  
    }  
}  
}  

Output:

Print a Given Matrix in Spiral Form

There are many approaches that can be used to print a matrix in spiral form.

SpiralToMatrixExample.java

import java.io.*;  
public class SpiralToMatrixExample   
{  
//Function print matrix in spiral form  
static void spiralPrint(int m, int n, int a[][])  
{  
int i, k = 0, l = 0;  
/* k - starting row index 
m - ending row index 
l - starting column index 
n - ending column index 
i - iterator 
*/  
while (k < m && l < n)   
{  
//prints the first row from the remaining rows  
for (i = l; i < n; ++i)   
{  
System.out.print(a[k][i] + " ");  
}  
k++;  
  
//prints the last column from the remaining columns  
for (i = k; i < m; ++i)   
{  
System.out.print(a[i][n - 1] + " ");  
}  
n--;  
//prints the last row from the remaining rows   
if (k < m)   
{  
for (i = n - 1; i >= l; --i)   
{  
System.out.print(a[m - 1][i] + " ");  
}  
m--;  
}  
//prints the first column from the remaining columns  
if (l < n)   
{  
for (i = m - 1; i >= k; --i)   
{  
System.out.print(a[i][l] + " ");  
}  
l++;  
}  
}  
}  
//driver Code  
public static void main(String args[])  
{  
int row = 3;  
int col = 6;  
//array to print in spiral form  
int arr[][] = { { 10, 20, 30, 40, 50, 60 }, { 70, 80, 90, 100, 110, 120 }, { 130, 140, 150, 160, 170, 180 } };  
//function Calling  
spiralPrint(row, col, arr);  
}  
} 

Output:

10 20 30 40 50 60 120 180 170 160 150 140 130 70 80 90 100 110