¿Hay alguna forma de detectar un lenguaje RTL en Java?

Question

Necesito poder detectar si el idioma actual que mi usuario está viendo es un lenguaje RTL (de derecha a izquierda) como el árabe.

Por el momento estoy detectando esto basado en el código de idioma de la propiedad del sistema user.language, pero debe haber una manera mejor.

Answer 1

ComponentOrientation.getOrientation(new Locale(System.getProperty("user.language"))).isLeftToRight(); 

• Resource

Answer 2

me sentí un poco sucio depender de las clases AWT que son bastante viejo y que estaba tratando con BCP-47 códigos de lenguaje, por lo que terminó copiando el código de Google Closure plantillas:

/** 
* A regular expression for matching right-to-left language codes. 
* See {@link #isRtlLanguage} for the design. 
*/ 
private static final Pattern RtlLocalesRe = Pattern.compile(
    "^(ar|dv|he|iw|fa|nqo|ps|sd|ug|ur|yi|.*[-_](Arab|Hebr|Thaa|Nkoo|Tfng))" + 
    "(?!.*[-_](Latn|Cyrl)($|-|_))($|-|_)"); 
/** 
* Check if a BCP 47/III language code indicates an RTL language, i.e. either: 
* - a language code explicitly specifying one of the right-to-left scripts, 
* e.g. "az-Arab", or<p> 
* - a language code specifying one of the languages normally written in a 
* right-to-left script, e.g. "fa" (Farsi), except ones explicitly specifying 
* Latin or Cyrillic script (which are the usual LTR alternatives).<p> 
* The list of right-to-left scripts appears in the 100-199 range in 
* http://www.unicode.org/iso15924/iso15924-num.html, of which Arabic and 
* Hebrew are by far the most widely used. We also recognize Thaana, N'Ko, and 
* Tifinagh, which also have significant modern usage. The rest (Syriac, 
* Samaritan, Mandaic, etc.) seem to have extremely limited or no modern usage 
* and are not recognized. 
* The languages usually written in a right-to-left script are taken as those 
* with Suppress-Script: Hebr|Arab|Thaa|Nkoo|Tfng in 
* http://www.iana.org/assignments/language-subtag-registry, 
* as well as Sindhi (sd) and Uyghur (ug). 
* The presence of other subtags of the language code, e.g. regions like EG 
* (Egypt), is ignored. 
*/ 
public static boolean isRtlLanguage(String languageString) { 
    return languageString != null && 
     RtlLocalesRe.matcher(languageString).find(); 
} 

Ver https://closure-templates.googlecode.com/svn-history/r21/trunk/java/src/com/google/template/soy/internal/i18n/BidiUtils.java