房上的猫：二维数组

public static void main(String[] args) {
        int[][] a = new int[3][];

        a[0] = new int[2];
        a[1] = new int[3];
        a[2] = new int[1];
        
        //Error:不能空缺第一维大小
        //列：int[][] b = new int [][3]  是错误的
    }
}

public class Aini {

    public static void main(String[] args) {
        int[][] a = new int[][]{{1,2,3},{4},{5,6,7,8}};

        for (int i = 0; i < a.length; i++) {
            for (int j = 0; j < a[i].length; j++) {
                System.out.print(a[i][j]+"");
            }
            System.out.println("");
        }
        
    }
}