toUpperCaseLocale() vs toUpperCase() - Now targeting Android 4.2

Question

Since I targeted a newer SDK version of Android, I have been getting a warning on this line of code: ``` return getString(R.string.usertab1).toUpperCase() ``` When I hover over it, it says: Implicitly using the default locale is a common source of bugs: Use `toUpperCase(Locale)` instead. Does anyone know how to remove this error? And why is it now a preferred way to use this method? I get this is the answer, to use `toUpperCase(Locale)` but having trouble implementing it. Where does the `Locale` object come from?

Accepted Answer

You could explicitly use the default locale:

```
return getString(R.string.usertab1).toUpperCase(Locale.getDefault());
```

Basically, you don't want to implicitly allow the device to use the default, because this can mean you simply ignored the fact that it could be an issue. For machine-readable content, you may want to specify a specific locale (such as `Locale.ENGLISH`) to ensure you always get the reusability you want out of the data. For showing the user, explicitly specifying the default locale should be fine.

For a more complete read:

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.

-- `Locale` developer documentation

toUpperCaseLocale() vs toUpperCase() - Now targeting Android 4.2

Solution

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