1、abs取绝对值，具体代码如下：
System.out.println(Math.abs(-10.5)); //10.5 System.out.println(Math.abs(10.5)); //10.5
2、ceil含义是天花板的意思，即向上取值，具体代码如下：
System.out.println(Math.ceil(-11.1)); //-11.0 System.out.println(Math.ceil(9.7)); //10.0 System.out.println(Math.ceil(-0.8)); //-0.0 System.out.println(Math.ceil(0.0)); //0.0 System.out.println(Math.ceil(-0.0)); //-0.0
3、floor是地板的意思，即向下取值，具体代码如下：
System.out.println(Math.floor(-11.1)); //-12.0 System.out.println(Math.floor(9.7)); //9.0 System.out.println(Math.floor(-0.8)); //-1.0 System.out.println(Math.floor(0.0)); //0.0 System.out.println(Math.floor(-0.0)); //-0.0
4、max是两个值中返回大值，具体代码如下：
System.out.println(Math.max(-11.1, -10)); //-10.0 System.out.println(Math.max(9.7, 10)); //10.0 System.out.println(Math.max(0.0, -0.0)); //0.0
5、min是两个值中返回大值，具体代码如下：
System.out.println(Math.min(-11.1, -10)); //-11.1 System.out.println(Math.min(9.7, 10)); //9.7 System.out.println(Math.min(0.0, -0.0)); //-0.0
6、random取得一个大于或者等于0.0小于不等于1.0的随机数，具体代码如下：
System.out.println(Math.random()); //0.07458754924313239 System.out.println(Math.random()); //0.33527604004604568
7、rint是四舍五入，返回double值，值为"*.5"时会取偶数，具体代码如下：
System.out.println(Math.rint(10.1)); //10.0 System.out.println(Math.rint(10.7)); //11.0 System.out.println(Math.rint(11.5)); //12.0 System.out.println(Math.rint(10.5)); //10.0 System.out.println(Math.rint(10.51)); //11.0 System.out.println(Math.rint(-10.5)); //-10.0 System.out.println(Math.rint(-11.5)); //-12.0 System.out.println(Math.rint(-10.51)); //-11.0 System.out.println(Math.rint(-10.7)); //-11.0 System.out.println(Math.rint(-10.1)); //-10.0
8、round是四舍五入，值为float时返回int值，值为double时返回long值，具体代码如下：
System.out.println(Math.round(10.1)); //10 System.out.println(Math.round(10.7)); //11 System.out.println(Math.round(10.5)); //11 System.out.println(Math.round(10.51)); //11 System.out.println(Math.round(-10.5)); //-10 System.out.println(Math.round(-10.51)); //-11 System.out.println(Math.round(-10.6)); //-11 System.out.println(Math.round(-10.2)); //-10
