SpiralMatrix.java

public class Main
{
	 public static void main(String[] args) {
      
      int a[][] = { { 1,   2,  3, 4 },
                    { 14, 15, 16, 5 },
                    { 13, 20, 17, 6 },
                    { 12, 19, 18, 7 },
                    { 11, 10, 9,  8 }};
     
       int rowStart = 0, rowEnd = a.length;
       int colStart = 0, colEnd = a[0].length;
       
       while(rowStart < rowEnd && colStart < colEnd)
       {
         //print top row (left to right)
         for(int i= colStart;i<colEnd;i++)
           System.out.print(a[rowStart][i]+ " ");
           
          rowStart+=1;
           
         //print right column (top to bottom)
         for(int i=rowStart;i<rowEnd;i++)
           System.out.print(a[i][colEnd - 1] + " ");
          
          colEnd-=1;
          
         // print bottom row (right to left)
         for(int i = colEnd - 1;i >= colStart;i--)
           System.out.print(a[rowEnd - 1][i] + " ");
           
          rowEnd-=1;
           
          // print left column (bottom to top)
          for(int i = rowEnd - 1;i >= rowStart;i--)
           System.out.print(a[i][colStart]+ " ");
           
          colStart+=1;
          
       }
    }
}