Java double 到具有特定精度的字符串
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Java double to string with specific precision
提问by user3009344
I would like to convert doubleinto String. I want it to have as few digits as possible and maximally 6.
我想转换double成String. 我希望它具有尽可能少的数字，最多为 6。
So I found String.format("%.6f", d)which converts my 100.0into 100.000000.
Max precision works correctly, but I would like it to be converted to 100(minimum precision).
Have you got any idea what method is working like that?
所以我发现String.format("%.6f", d)哪个将 my 转换100.0为100.000000. 最大精度工作正常，但我希望将其转换为100（最小精度）。你知道什么方法是这样工作的吗？
采纳答案by Thomas
Use DecimalFormat: new DecimalFormat("#.0#####").format(d).
使用DecimalFormat：new DecimalFormat("#.0#####").format(d)。
This will produce numbers with 1 to 6 decimal digits.
这将产生具有 1 到 6 个十进制数字的数字。
Since DecimalFormatwill use the symbols of the default locale, you might want to provide which symbols to use:
由于DecimalFormat将使用默认语言环境的符号，您可能需要提供要使用的符号：
//Format using english symbols, e.g. 100.0 instead of 100,0
new DecimalFormat("#.0#####", DecimalFormatSymbols.getInstance( Locale.ENGLISH )).format(d)
In order to format 100.0 to 100, use the format string #.######.
要将 100.0 格式化为 100，请使用格式字符串#.######。
Note that DecimalFormatwill round by default, e.g. if you pass in 0.9999999you'll get the output 1. If you want to get 0.999999instead, provide a different rounding mode:
请注意，DecimalFormat默认情况下会舍入，例如，如果您传入，0.9999999您将获得输出1。如果你想得到0.999999，请提供不同的舍入模式：
DecimalFormat formatter = new DecimalFormat("#.######", DecimalFormatSymbols.getInstance( Locale.ENGLISH ));
formatter.setRoundingMode( RoundingMode.DOWN );
String s = formatter.format(d);
回答by Paul Samsotha
String.format("%.0", d)will give you no decimal places
String.format("%.0", d)不会给你小数位
-or-
-或者-
String.format("%d", (int)Math.round(f))
String.format("%d", (int)Math.round(f))
回答by brettw
This is a cheap hack that works (and does not introduce any rounding issues):
这是一个有效的廉价黑客（并且不会引入任何舍入问题）：
String string = String.format("%.6f", d).replaceAll("(\.\d+?)0*$", "");
回答by Travis
Couldn't you just make a setPrecision function, sort of like this
你能不能做一个 setPrecision 函数，有点像这样
private static String setPrecision(double amt, int precision){
return String.format("%." + precision + "f", amt);
}
then of course to call it
那么当然要调用它
setPrecision(variable, 2); //
Obviously you can tweek it up for rounding or whatever it is you need to do.
显然，您可以将其调整为四舍五入或您需要做的任何事情。
