java 向下取整和向上取整

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); //1.75
System.out.println(Math.ceil(c)); //2.0
System.out.println(Math.floor(c)); //1.0