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javavalidationlocale

How to validate & instantiate Java Locale from strings?

My app is being fed string from an external process, where each string is either 2- or 5-characters in length, and represents a java.util.Locales. For example:

en-us

ko

The first example is a 5-char string where "en" is the ISO language code, and "us" is the ISO country code. This should correspond to the "en_US" Locale. The second example is only a 2-char string, where "ko" is the ISO language code, and should correspond to the "ko_KR" (Korean) Locale.

I need a way to take these strings (either the 2- or 5-char variety), validate it (as a supported Java 6 Locale), and then create a Locale instance with it.

I would have hoped that Locale came with such validation out of the box, but unfortunately this code runs without exceptions being thrown:

Locale loc = new Locale("waawaaweewah", "greatsuccess");

// Prints: "waawaaweewah"
System.out.println(loc.getDisplayLanguage());

So I ask, given me the 2 forms that these string will be given to me in, how can I:

  • Validate the string (both forms) and throw an exception for strings corresponding to non-existent or unsupported Java 6 Locales; and
  • Instantiate a new Locale from the string? This question really applies to the 2-char form, where I might only have "ko" and need it to map to the "ko_KR" Locale, etc.

Thanks in advance!

Solution

  • Locale.getISOCountries() and Locale.getISOLanguages()

    return a list of all 2-letter country and language codes defined in ISO 3166 and ISO 639 respectively and can be used to create Locales.

    You can use this to validate your inputs.