Java Math.round函数详解

public class TestMathRound {
    public static void main(String[] args) {
        System.out.println("小数点后第一位=5");
        System.out.println("正数：Math.round(11.5)=" + Math.round(11.5));//12
        System.out.println("负数：Math.round(-11.5)=" + Math.round(-11.5));//-11
        System.out.println();
        System.out.println("小数点后第一位<5");
        System.out.println("正数：Math.round(11.46)=" + Math.round(11.46));//11
        System.out.println("负数：Math.round(-11.46)=" + Math.round(-11.46));//-11
        System.out.println();
        System.out.println("小数点后第一位>5");
        System.out.println("正数：Math.round(11.68)=" + Math.round(11.68));//12
        System.out.println("负数：Math.round(-11.68)=" + Math.round(-11.68));//-12
    }
}

    public static long round(double a) {
        if (a != 0x1.fffffffffffffp-2) // greatest double value less than 0.5
            return (long)floor(a + 0.5d);
        else
            return 0;
    }