Math（初学）

package day01;

public class Case12 {
    public static void main(String[] args) {
        System.out.println(Math.abs(-3.14));//绝对值
        System.out.println(Math.ceil(3.9));//向上取整
        System.out.println(Math.floor(3.1));//向下取整
        System.out.println(Math.round(20.4));//四舍五入
        System.out.println(Math.PI);
    }
}