How to validate a locale in java?

Question

I read a file in an application that specifies a language code:

public void setResources(String locale) {

    // validate locale
    // ULocale lo = new ULocale(locale);
    // System.out.println(lo.getDisplayCountry());

}

that must be in the format: <ISO 639 language code>_<ISO 3166 region code> eg. en_UK, en_US etc. Is it possible to validate that the locale string is valid before continuing?

Answer 1

You can get the available locales like so and enumerate them to see if the locale is valid

boolean isValidLocale(String value) {
  Locale []locales = Locale.getAvailableLocales();
  for (Locale l : locales) {
    if (value.equals(l.toString()) {
      return true;
    }
  }
  return false;
}

Answer 2

You could check if the String is contained in the Arrays returned by the getISOCountries() or getISOLanguages() methods of Locale. Its kinda crude but may actually work. You could also extract all available Locales with getAvailableLocales() and search them for display names.

Answer 3

I do not know ULocale, but if you mean java.util.Locale, the following code may do:

public void setResources(String locale) {
  // validate locale
  Locale lo = parseLocale(locale);
  if (isValid(lo) {
    System.out.println(lo.getDisplayCountry());
  } else {
    System.out.println("invalid: " + locale);
  }
}

private Locale parseLocale(String locale) {
  String[] parts = locale.split("_");
  switch (parts.length) {
    case 3: return new Locale(parts[0], parts[1], parts[2]);
    case 2: return new Locale(parts[0], parts[1]);
    case 1: return new Locale(parts[0]);
    default: throw new IllegalArgumentException("Invalid locale: " + locale);
  }
}

private boolean isValid(Locale locale) {
  try {
    return locale.getISO3Language() != null && locale.getISO3Country() != null;
  } catch (MissingResourceException e) {
    return false;
  }
}

EDIT: added validation

Answer 4

Now I just do:

ULocale uLocale = new ULocale(locale);
if (uLocale.getCountry() != null && !uLocale.getCountry().isEmpty()) {
  ...
}

which works fine.