格式化双精度到2位小数不起作用 [英] Formatting double to 2 decimals doesn't work
问题描述
3.499999999999999
to:
3.50
我已经使用了这两种方法:
DecimalFormat df = new DecimalFormat(0.00);
double result = Double.valueOf(df.format(input));
System.out.println(answer);
和
public double round(double input)
{
int decimalPlace = 2;
BigDecimal bd = new BigDecimal(input);
bd = bd.setScale(decimalPlace,BigDecimal.ROUND_UP);
return(bd.doubleValue());
}
但是它保持打印:
3.5
有没有人有这个解决方案?因为我真的认为这应该是正常的。感谢您的帮助。
您的第一个解决方案真的很真实。只要这样做:
DecimalFormat df = new DecimalFormat(0.00);
System.out.println(df.format(input));
您的版本不起作用的原因是您正在使用输入
double,将其格式化为一个 String
与2dp,然后将其转换回 double
。 System.out.println
然后像往常一样打印 double
,没有特殊的小数位数规则。 / p>
I want to round this double:
3.499999999999999
to:
3.50
And I already used these two methods:
DecimalFormat df = new DecimalFormat("0.00");
double result = Double.valueOf(df.format(input));
System.out.println(answer);
and
public double round(double input)
{
int decimalPlace = 2;
BigDecimal bd = new BigDecimal(input);
bd = bd.setScale(decimalPlace,BigDecimal.ROUND_UP);
return (bd.doubleValue());
}
But It keeps printing:
3.5
Does anyone have a solution for this? Because I really think that this should work. Thanks for your help.
Your first solution is really, really close. Just do this:
DecimalFormat df = new DecimalFormat("0.00");
System.out.println(df.format(input));
The reason your version doesn't work is that you're taking the input
double, formatting it as a String
with 2dp, but then converting it back to a double
. System.out.println
is then printing the double
as it always would, with no special decimal-place rules.
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