java编写一个将实数四舍五入到小数点后第n位的函数,并调用此函数将一个实数舍入到

java编写一个将实数四舍五入到小数点后第n位的函数,并调用此函数将一个实数舍入到

 public static void main(String[] args) {
        ss(435.546546546,5);
    }
    public static void ss(double f,int n){
        System.out.println(String.format("%."+n+"f", f));
    }

/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
    static double round(double d, int n)
    {
        return ((int)(d * Math.pow(10.0, (double)(n)) + 0.5)) / Math.pow(10.0, (double)(n));
    }
    public static void main (String[] args) throws java.lang.Exception
    {
        double d = 12.34567890123;
        d = round(d, 1);
        System.out.println(d);
        d = 12.34567890123;
        d = round(d, 2);
        System.out.println(d);
        d = 12.34567890123;
        d = round(d, 3);
        System.out.println(d);
        d = 12.34567890123;
        d = round(d, 4);
        System.out.println(d);
        d = 12.34567890123;
        d = round(d, 5);
        System.out.println(d);
    }
} 

12.3
12.35
12.346
12.3457
12.34568

http://ideone.com/VfqlSn

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