public class TestMath {

    public static void main(String[] args) {

        System.out.println(Math.E);

        System.out.println(Math.PI);

        System.out.println(Math.abs(-3.5));

        System.out.println(Math.ceil(3.5)); // >=

        System.out.println(Math.floor(3.5)); // <=

        System.out.println(Math.pow(2, 3));

        System.out.println(Math.random());// 0-1之间随机数

        System.out.println(Math.round(3.5)); // 四舍五入

    }

}

2.718281828459045

3.141592653589793

3.5

4.0

3.0

8.0

0.2921187058255972

4