如何输出小数时按规定的位数输出。。

[wujevons]

如
x=12.34
OutNum(x,2) == 12.34
OutNum(x,3) == 12.340
OutNum(x,4) == 12.3400

[rinehart]

import java.text.DecimalFormat;

String a = new DecimalFormat("###,###,###.##").format(100.5 );
System.out.println("a="+a);

结果：
a=100.50

[vdragon]

public class numformat
{
static String num(String xx, String ii)
{
String str = new String();
try
{
float x= Float.parseFloat(xx);
int i = Integer.parseInt(ii);
if (i < 0)
{
return "i is error";
}
if (i == 0)
{
if (xx.indexOf(".") > -1)
{
str = xx.substring(0, xx.indexOf("."));
}
else
{
str = xx;
}
return str;
}
if (xx.indexOf(".") > -1)
{
int f = xx.substring(xx.indexOf(".")+1, xx.length()).length();
if (f < i)
{
for (int j = f; j < i; j++)
{
xx += "0";
}
}
else
{
xx = xx.substring(0, xx.indexOf(".") + i + 1);
}
}
else
{
xx += ".";
for (int j = 0; j < i; j++)
{
xx += "0";
}
}
str = xx;
return str;
}
catch (Exception e)
{
e.printStackTrace();
return "error";
}

}
public static void main(String[] args)
{
String x = args[0];
String i = args[1];
System.out.println("result:" + num(x, i));
}
}

[wujevons]

好呀！解决了，谢谢！