pattern generation

Here is an example of number spiral.

public class NumberSpiral{

public static void main(String[] args) {
    int dimension=5;
    int[][] spiralArray = new int[dimension][dimension];
    int num = (int) Math.ceil((dimension) / 2.0);

    int j;
    int len = dimension;
    int number = 1;

    for (int i = 0; i < num; i++) {
      for (j = 0; j < len; j++) {
        spiralArray[i][i + j] = number++;
      }
      for (j = 1; j < len; j++) {
        spiralArray[i + j][dimension - 1 - i] = number++;
      }
      for (j = len - 2; j > -1; j--) {
        spiralArray[dimension - 1 - i][i + j] = number++;
      }
      for (j = len - 2; j > 0; j--) {
        spiralArray[i + j][i] = number++;
      }
      len -= 2;
    }
    for (int[] row : spiralArray) {
      for (int elem : row) {
        System.out.printf("%3d", elem);
      }
      System.out.println();
    }
  }

}