关于math:Math类的三个方法比较-floor-ceil-round

public class Test {    public static void main(String[] args) {        double d1 = 3.4,    d2 = 3.6;   //负数        double d3 = -3.4,   d4 = -3.6;  //正数        float f1 = 4.4F,    f2 = 4.6F;  //负数        float f3 = -4.4F,   f4 = -4.6F; //正数        //floor()办法只能接管double类型,返回double类型        //向下取整,返回小于参数的最大整数        System.out.println(Math.floor(d1));//3.0        System.out.println(Math.floor(d2));//3.0        System.out.println(Math.floor(d3));//-4.0        System.out.println(Math.floor(d4));//-4.0        //ceil()办法只能接管double类型,返回double类型        //向上取整,返回大于参数的最小整数        System.out.println(Math.ceil(d1));//4.0        System.out.println(Math.ceil(d2));//4.0        System.out.println(Math.ceil(d3));//-3.0        System.out.println(Math.ceil(d4));//-3.0        //round()办法能够接管double类型,返回long类型        //示意“四舍五入”，算法为Math.floor(x+0.5)，行将参数加上0.5后再向下取整        System.out.println(Math.round(d1));//3        System.out.println(Math.round(d2));//4        System.out.println(Math.round(d3));//-3        System.out.println(Math.round(d4));//-4        //round()办法能够接管float类型,返回int类型        System.out.println(Math.round(f1));//4        System.out.println(Math.round(f2));//5        System.out.println(Math.round(f3));//-4        System.out.println(Math.round(f4));//-5    }}