Spiral Matrix

public class Solution {
    public List<Integer> spiralOrder(int[][] matrix) {
        List<Integer> result = new ArrayList<Integer>();
        if (matrix == null || matrix.length < 1 || matrix[0].length < 1) {
            return result;
        }
        int row = matrix.length;
        int col = matrix[0].length;
        int r = row;
        int c = col;
        int level = 0;
        while (r > 0 && c > 0) {
            if (r == 1) {
                for (int j = level; j < col - level; j++) {
                    result.add(matrix[level][j]);
                }
                break;
            }
            if (c == 1) {
                for (int i = level; i < row - level; i++) {
                    result.add(matrix[i][level]);
                }
                break;
            }
            for (int j = level; j < col - level - 1; j++) {
                result.add(matrix[level][j]);
            }
            for (int i = level; i < row - level - 1; i++) {
                result.add(matrix[i][col - level - 1]);
            }
            for (int j = col - level - 1; j > level; j--) {
                result.add(matrix[row - level - 1][j]);
            }
            for (int i = row - level - 1; i > level; i--) {
                result.add(matrix[i][level]);
            }
            c -= 2;
            r -= 2;
            level++;
        }
        return result;
    }
}