1 public class Test { 2     public static void main(String[] args) { 3         double d1 = 3.4,    d2 = 3.6;   //正数 4         double d3 = -3.4,   d4 = -3.6;  //负数 5   6         float f1 = 4.4F,    f2 = 4.6F;  //正数 7         float f3 = -4.4F,   f4 = -4.6F; //负数 8   9         //floor()方法只能接收double类型,返回double类型10         //向下取整,返回小于参数的最大整数11         System.out.println(Math.floor(d1));//3.012         System.out.println(Math.floor(d2));//3.013         System.out.println(Math.floor(d3));//-4.014         System.out.println(Math.floor(d4));//-4.015  16  17         //ceil()方法只能接收double类型,返回double类型18         //向上取整,返回大于参数的最小整数19         System.out.println(Math.ceil(d1));//4.020         System.out.println(Math.ceil(d2));//4.021         System.out.println(Math.ceil(d3));//-3.022         System.out.println(Math.ceil(d4));//-3.023  24  25         //round()方法可以接收double类型,返回long类型26         //表示“四舍五入”，算法为Math.floor(x+0.5)，即将参数加上0.5后再向下取整27         System.out.println(Math.round(d1));//328         System.out.println(Math.round(d2));//429         System.out.println(Math.round(d3));//-330         System.out.println(Math.round(d4));//-431  32         //round()方法可以接收float类型,返回int类型33         System.out.println(Math.round(f1));//434         System.out.println(Math.round(f2));//535         System.out.println(Math.round(f3));//-436         System.out.println(Math.round(f4));//-537     }38 }