java 除法向上，向下取整

向上取整用Math.ceil(double a)

向下取整用Math.floor(double a)

// 举例：

  double a=35;
  double b=20;
  double c = a/b;
  System.out.println("c===>"+c);   //1.75
  System.out.println("c===>"+Math.ceil(c)); //2.0
  System.out.println(Math.floor(c));  //1.0