如何正确显示最多两位小数（美分）的价格，包括 Java 中的尾随零？
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How to properly display a price up to two decimals (cents) including trailing zeros in Java?
提问by denchr
There is a good question on rounding decimals in Java here. But I was wondering how can I include the trailing zeros to display prices in my program like: $1.50, $1.00
有在Java的舍入小数一个很好的问题在这里。但我想知道如何在我的程序中包含尾随零以显示价格，例如：$1.50, $1.00
The simple solution of
简单的解决方法
String.format("%.2g%n", 0.912385);
works just fine, but omits the trailing zero if it is at the last decimal place. The issue comes up in my program even though I only use expressions like this:
工作正常，但如果它在最后一个小数位，则省略尾随零。即使我只使用这样的表达式，问题也出现在我的程序中：
double price = 1.50;
When I do calculations with different prices (add, multiply, etc.) the result is primarily displayed like this:
当我用不同的价格（加、乘等）进行计算时，结果主要显示如下：
.5000000000000003
So, using the String.format works fine for this purpose, but it truncates the above example to
因此，为此目的使用 String.format 效果很好，但它会将上面的示例截断为
.5
Is there a proper way to show the trailing zero at the second decimal place? Or both zeros if the output of a calculation should be
有没有正确的方法在小数点后第二位显示尾随零？或者如果计算的输出应该是两个零
.00
采纳答案by duffymo
I would recommend that you do this:
我建议你这样做：
NumberFormat currencyFormatter = NumberFormat.getCurrencyInstance();
double price = 2.50000000000003;
System.out.println(currencyFormatter.format(price));
This has the virtue of be locale-specific as well. This will work, for example, if you're in the euro zone instead of the US.
这也具有特定于区域设置的优点。例如，如果您在欧元区而不是美国，这将起作用。
回答by Bart Kiers
It can probably be done with String.format(...), but you could use DecimalFormat:
它可能可以用 String.format(...) 来完成，但你可以使用DecimalFormat：
double price = 2.50000000000003;
DecimalFormat formatter = new DecimalFormat("String s = String.format("$%.2f", 2.50);
.00");
System.out.println(formatter.format(price)); // print: .50
回答by dustmachine
Have you tried:
你有没有尝试过：
public static String getFormattedData(String actualString)
{
String subString = "0.0";
if(actualString.contains("."))
{
subString = actualString.substring(actualString.indexOf("."), actualString.trim().length());
if(Double.parseDouble(subString) > 0.0)
return actualString;
else
actualString = actualString.substring(0, actualString.indexOf("."));
}
return actualString;
}
That will do the trick.
这样就行了。
回答by Pascal Thivent
While others answers are perfectly valid (especially duffymo's one), you have a much bigger problem than formatting the display. You are actually using a totally wrongtype for a money amount which is a discretevalue. Instead of a double, you should really consider using a java.lang.BigDecimal.
虽然其他答案完全有效（尤其是 duffymo 的答案），但您遇到的问题比格式化显示要大得多。对于离散值的金额，您实际上使用了完全错误的类型。而不是 a ，您应该真正考虑使用 a 。doublejava.lang.BigDecimal
(EDIT: ... or a well implemented Money class as duffymo pointed out in a comment, for example classes from JScience's monetarymodule or the more recent Joda-Money- which has still to be released as an official version.)
（编辑：...或者像 duffymo 在评论中指出的那样实现良好的 Money 类，例如来自 JScience 的货币模块的类或最近的Joda-Money- 仍需作为正式版本发布。）
