循环填充矩阵

有一个矩阵，用序列沿边缘循环填充，例如指定行5，列3,则输出序列如下：

1 2 3
12 13 4
11 14 5
10 15 6
9 8 7

主要是状态之间的切换，注意切换的条件以及终止条件即可，Java代码实现如下：

public class OuterLoopMatrix {
    private int row = 1;
    private  int col = 1;
    private int[][] matrix = null;
    private enum Direction{
        RIGHT,DOWN,UP,LEFT
    }
    private Direction dir;

    /**
     * Constructor
     * @param row
     * @param col
     */
    public OuterLoopMatrix(int row , int col){
        if(row < 0 && col < 0){
            this.row = 1;
            this.col = 1;
            System.out.println("row and col must be greater than 0");
        }
        this.row = row;
        this.col = col;
        this.matrix = new int[row][col];
        this.dir = Direction.RIGHT;
    }

    /**
     * print the matrix
     */
    public void printMatrix(){
        for (int i = 0; i < row; i++) {
            for (int j = 0; j < col; j++) {
                System.out.print(matrix[i][j]);
                System.out.print("	");
            }
            System.out.println();
        }
    }

    /**
     * generate the matrix
     */
    public void genMatrix(){
        int count=1;
        int cr=0;
        int cc=0;
        //    state machine
        while(count <= col * row){
            switch (this.dir) {
                case RIGHT:
                    if(cc < col && matrix[cr][cc] == 0){
                        matrix[cr][cc]=count;
                        cc++;
                        count++;
                    }
                    else{
                        cc--;
                        this.dir = Direction.DOWN;
                        cr++;
                    }
                    break;
                case DOWN:
                    if(cr < row && matrix[cr][cc] == 0){
                        matrix[cr][cc]=count;
                        cr++;
                        count++;
                    }
                    else{
                        cr--;
                        this.dir = Direction.LEFT;
                        cc--;
                    }
                    break;
                case LEFT:
                    if(cc >=0 && matrix[cr][cc] == 0){
                        matrix[cr][cc]=count;
                        cc--;
                        count++;
                    }
                    else{
                        cc++;
                        this.dir = Direction.UP;
                        cr--;
                    }
                    break;
                case UP:
                    if(cr >=0 && matrix[cr][cc] == 0){
                        matrix[cr][cc]=count;
                        cr--;
                        count++;
                    }
                    else{
                        cr++;
                        this.dir = Direction.RIGHT;
                        cc++;
                    }
                    break;
                default:
                    break;
            }
        }
    }
}