NumberFormat 括号内的文本到负数

Question

我使用

在 Activity 中显示负数

  double value = -1.0;
  NumberFormat defaultFormat = NumberFormat.getCurrencyInstance(Locale.US);
  String formattedText = defaultFormat.format(value);

但是当我运行在 Samsung Galaxy S5 (Android 4.4.2) 上执行此操作时，我得到 (.0) 而 Nexus 5 (Android 5.1.1) 给出的 -.0.

这里有什么问题？

Answer 1

From the documentation:

Be wary of the default locale

Note that there are many convenience methods that automatically use the default locale, but using them may lead to subtle bugs.

The default locale is appropriate for tasks that involve presenting data to the user. In this case, you want to use the user's date/time formats, number formats, rules for conversion to lowercase, and so on. In this case, it's safe to use the convenience methods.

The default locale is not appropriate for machine-readable output. The best choice there is usually Locale.US – this locale is guaranteed to be available on all devices, and the fact that it has no surprising special cases and is frequently used (especially for computer-computer communication) means that it tends to be the most efficient choice too.

A common mistake is to implicitly use the default locale when producing output meant to be machine-readable. This tends to work on the developer's test devices (especially because so many developers use en_US), but fails when run on a device whose user is in a more complex locale.

For example, if you're formatting integers some locales will use non-ASCII decimal digits. As another example, if you're formatting floating-point numbers some locales will use ',' as the decimal point and '.' for digit grouping. That's correct for human-readable output, but likely to cause problems if presented to another computer (parseDouble(String) can't parse such a number, for example). You should also be wary of the toLowerCase() and toUpperCase() overloads that don't take a Locale: in Turkey, for example, the characters 'i' and 'I' won't be converted to 'I' and 'i'. This is the correct behavior for Turkish text (such as user input), but inappropriate for, say, HTTP headers.

Answer 2

感谢@Bonati

public static String formatAmount(double value) {
        NumberFormat numberFormat = new DecimalFormat("'$'0.00");
        return numberFormat.format(value);
    }

这对我来说很好。

NumberFormat 括号内的文本到负数

NumberFormat bracketted text to negative numbers

android

locale

currency

number-formatting