Math的round方法

代码如下，后面的注释是输出的结果

public static void main(String[] args) {
        System.out.println(Math.round(0.399));//0
        System.out.println(Math.round(0.4));//0
        System.out.println(Math.round(0.41));//0
        System.out.println(Math.round(0.499));//0
        System.out.println(Math.round(0.5));//1
        System.out.println(Math.round(0.51));//1
        System.out.println(Math.round(0.6));//1
        System.out.println("======================");
        System.out.println(Math.round(-0.6));//-1
        System.out.println(Math.round(-0.51));//-1
        System.out.println(Math.round(-0.5));//0
        System.out.println(Math.round(-0.499));//0
        System.out.println(Math.round(-0.41));//0
        System.out.println(Math.round(-0.4));//0
        System.out.println(Math.round(-0.399));//0
    }

 总结，round的进位是向数轴的右方向进位的，而不是按照数的绝对值进行四舍五入的

关于Math对三角函数表示的一些知识点查看https://blog.csdn.net/River_Continent/article/details/80637952