Math

package cn.learn.basic;
/*
  java.util.Math类含有大量的静态方法
  public static double abs(double num)  -求double绝对值
  public static double ceil(double num)  -向上取整
  public static double floor(double num)  -向下取整
  public static long round(double) -四舍五入
 */
public class MathApi {
    public static void main(String[] args) {
        double num=-1.2;
        System.out.println(Math.abs(num)); //1.2
        System.out.println(Math.ceil(num)); //-1.0

    }
}