Java Math类常用方法大全

1.简介

Java的Math类封装了很多与数学有关的属性和方法。

2.举例说明

代码：

private void mathMethod(){

        /**
         * Math.sqrt()//计算平方根
         * Math.cbrt()//计算立方根
         * Math.hypot(x,y)//计算 (x的平方+y的平方)的平方根
         */

        Log.d("TAG","Math.sqrt(16)----:"+Math.sqrt(16));//4.0
        Log.d("TAG","Math.cbrt(8)----:"+Math.cbrt(8));//2.0
        Log.d("TAG","Math.hypot(3,4)----:"+Math.hypot(3,4));//5.0

        /**
         * Math.pow(a,b)//计算a的b次方
         * Math.exp(x)//计算e^x的值
         * */

        Log.d("TAG","------------------------------------------");
        Log.d("TAG","Math.pow(3,2)----:"+Math.pow(3,2));//9.0
        Log.d("TAG","Math.exp(3)----:"+Math.exp(3));//20.085536923187668

        /**
         * Math.max();//计算最大值
         * Math.min();//计算最小值
         * */

        Log.d("TAG","------------------------------------------");
        Log.d("TAG","Math.max(2.3,4.5)----:"+Math.max(7,15));//15
        Log.d("TAG","Math.min(2.3,4.5)----:"+Math.min(2.3,4.5));//2.3

        /**
         * Math.abs求绝对值
         */

        Log.d("TAG","------------------------------------------");
        Log.d("TAG","Math.abs(-10.4)----:"+Math.abs(-10.4));//10.4
        Log.d("TAG","Math.abs(10.1)----:"+Math.abs(10.1));//10.1

        /**
         * Math.ceil天花板的意思，就是返回大的值
         */

        Log.d("TAG","------------------------------------------");
        Log.d("TAG","Math.ceil(-10.1)----:"+Math.ceil(-10.1));//-10.0
        Log.d("TAG","Math.ceil(10.7)----:"+Math.ceil(10.7));//11.0
        Log.d("TAG","Math.ceil(-0.7)----:"+Math.ceil(-0.7));//-0.0
        Log.d("TAG","Math.ceil(0.0)----:"+Math.ceil(0.0));//0.0
        Log.d("TAG","Math.ceil(-0.0)----:"+Math.ceil(-0.0));//-0.0
        Log.d("TAG","Math.ceil(-1.7)----:"+Math.ceil(-1.7));//-1.0

        /**
         * Math.floor地板的意思，就是返回小的值
         */

        Log.d("TAG","------------------------------------------");
        Log.d("TAG","Math.floor(-10.1)----:"+Math.floor(-10.1));//-11.0
        Log.d("TAG","Math.floor(10.7)----:"+Math.floor(10.7));//10.0
        Log.d("TAG","Math.floor(-0.7)----:"+Math.floor(-0.7));//-1.0
        Log.d("TAG","Math.floor(0.0)----:"+Math.floor(0.0));//0.0
        Log.d("TAG","Math.floor(-0.0)----:"+Math.floor(-0.0));//-0.0

        /**
         * Math.random 取得一个大于或者等于0.0小于不等于1.0的随机数[0,1)
         */

        Log.d("TAG","------------------------------------------");
        Log.d("TAG","Math.random()----:"+Math.random());//输出[0,1)间的随机数 0.8979626325354049
        Log.d("TAG","Math.random()*100----:"+Math.random()*100);//输出[0,100)间的随机数 32.783762836248144

        /**
         * Math.rint 四舍五入
         * 返回double值
         */

        Log.d("TAG","------------------------------------------");
        Log.d("TAG","Math.rint(10.1)----:"+Math.rint(10.1));//10.0
        Log.d("TAG","Math.rint(10.7)----:"+Math.rint(10.7));//11.0
        Log.d("TAG","Math.rint(-10.5)----:"+Math.rint(-10.5));//-10.0
        Log.d("TAG","Math.rint(-10.51)----:"+Math.rint(-10.51));//-11.0
        Log.d("TAG","Math.rint(-10.2)----:"+Math.rint(-10.2));//-10.0
        Log.d("TAG","Math.rint(9)----:"+Math.rint(9));//9.0


        /**
         * Math.round 四舍五入
         * float时返回int值，double时返回long值
         */

        Log.d("TAG","------------------------------------------");
        Log.d("TAG","Math.round(10.1)----:"+Math.round(10.1));//10
        Log.d("TAG","Math.round(10.7)----:"+Math.round(10.7));//11
        Log.d("TAG","Math.round(-10.5)----:"+Math.round(-10.5));//-10
        Log.d("TAG","Math.round(-10.51)----:"+Math.round(-10.51));//-11
        Log.d("TAG","Math.round(-10.2)----:"+Math.round(-10.2));//-10
        Log.d("TAG","Math.round(9)----:"+Math.round(9));//9

        /**
         * Math.nextUp(a) 返回比a大一点点的浮点数
         * Math.nextDown(a) 返回比a小一点点的浮点数
         * Math.nextAfter(a,b) 返回(a,b)或(b,a)间与a相邻的浮点数 b可以比a小
         * */

        Log.d("TAG","------------------------------------------");
        Log.d("TAG","Math.nextUp(1.2)----:"+Math.nextUp(1.2));//1.2000000000000002
        Log.d("TAG","Math.nextDown(1.2)----:"+Math.nextDown(1.2));//1.1999999999999997
        Log.d("TAG","Math.nextAfter(1.2, 2.7)----:"+Math.nextAfter(1.2, 2.7));//1.2000000000000002
        Log.d("TAG","Math.nextAfter(1.2, -1)----:"+Math.nextAfter(1.2, -1));//1.1999999999999997

    }

结果：

Math.sqrt(16)----:4.0
Math.cbrt(8)----:2.0
Math.hypot(3,4)----:5.0
------------------------------------------
Math.pow(3,2)----:9.0
Math.exp(3)----:20.085536923187668
------------------------------------------
Math.max(2.3,4.5)----:15
Math.min(2.3,4.5)----:2.3
------------------------------------------
Math.abs(-10.4)----:10.4
Math.abs(10.1)----:10.1
------------------------------------------
Math.ceil(-10.1)----:-10.0
Math.ceil(10.7)----:11.0
Math.ceil(-0.7)----:-0.0
Math.ceil(0.0)----:0.0
Math.ceil(-0.0)----:-0.0
Math.ceil(-1.7)----:-1.0
------------------------------------------
Math.floor(-10.1)----:-11.0
Math.floor(10.7)----:10.0
Math.floor(-0.7)----:-1.0
Math.floor(0.0)----:0.0
Math.floor(-0.0)----:-0.0
------------------------------------------
Math.random()----:0.8979626325354049
Math.random()*100----:32.783762836248144
------------------------------------------
Math.rint(10.1)----:10.0
Math.rint(10.7)----:11.0
Math.rint(-10.5)----:-10.0
Math.rint(-10.51)----:-11.0
Math.rint(-10.2)----:-10.0
Math.rint(9)----:9.0
------------------------------------------
Math.round(10.1)----:10
Math.round(10.7)----:11
Math.round(-10.5)----:-10
Math.round(-10.51)----:-11
Math.round(-10.2)----:-10
Math.round(9)----:9
------------------------------------------
Math.nextUp(1.2)----:1.2000000000000002
Math.nextDown(1.2)----:1.1999999999999997
Math.nextAfter(1.2, 2.7)----:1.2000000000000002
Math.nextAfter(1.2, -1)----:1.1999999999999997