【java】java.lang.Math：public static long round(double a)和public static int round(float a)

package math;

public class TestMath_round {
    public static void main(String[] args) {
        System.out.println(Math.round(0.5));//1
        System.out.println(Math.round(-0.5));//0
        System.out.println(Math.round(-0.501));//-1
        //Math类的四舍五入方法round进行负数操作时小数位大于0.5才进位，小于等于0.5不进位
    }
}

package math;

import java.math.BigDecimal;

class MyRound{
    public static double div(double d,int scale){
        BigDecimal b1=new BigDecimal(d);
        BigDecimal b2=new BigDecimal(1);
        return b1.divide(b2, scale, BigDecimal.ROUND_HALF_UP).doubleValue();
    }
}
public class TestMath_round {
    public static void main(String[] args) {
        System.out.println(Math.round(0.5));//1
        System.out.println(Math.round(-0.5));//0
        System.out.println(Math.round(-0.501));//-1
        //Math类的四舍五入方法round进行负数操作时小数位大于0.5才进位，小于等于0.5不进位
        System.out.println(MyRound.div(-0.5, 0));//-1.0
        //改进后为通常的四舍五入。
    }
}