I saw someone mention this as a fun problem, so I did it.

MatrixSpiral.java

public class SpiralMatrix {

  public static void spiralPrint( int[][] matrix ) {

    int height = matrix.length;
    int width = matrix[0].length;

    int currCol = 0;
    int currRow = 0;

    int stopAtRow = height / 2;

    if( height % 2 == 1 ) {
      stopAtRow = height / 2 + 1;
    }


    while(currRow < stopAtRow) {

      // Across ->
      for (int i = currCol; i < width - currCol; ++i) {
        System.out.print(matrix[currRow][i] + "  ");
      }

      // Down
      for (int i = currRow + 1; i < height - currRow; ++i) {
        System.out.print(matrix[i][width - 1 - currCol] + " ");
      }

      // Across <-
      for (int i = width - 2 - currCol; i > currCol; --i) {
        System.out.print(matrix[height - 1 - currRow][i] + " ");
      }

      // Up
      for (int i = height - 1 - currRow; i > currCol; --i) {
        System.out.print(matrix[i][currCol] + " ");
      }

      currCol++;
      currRow++;
    }


  }

  public static void main(String[] args) {
    int[][] matrix = new int[][] {
        {1, 2, 3, 4, 5, 6},
        {7, 8, 9, 10,11,12},
        {13,14,15,16,17,18},
        {19,20,21,22,23,24},
        {25,26,27,28,29,30},
        {31,32,33,34,35,36},
    };

    spiralPrint( matrix );
  }
}