Identifying RTL language in Android

Question

Is there a way to identify RTL (right-to-left) language, apart from testing language code against all RTL languages?

Since API 17+ allows several resources for RTL a

Answer 1

There's a really simple way to check the layout direction of a view, but it falls back to LTR on pre API 17 devices:

ViewUtils.isLayoutRtl(View view);

the ViewUtils class comes bundled with the support v7 library, so it should be available already if you're using the appcompat library.

Answer 2

Just use this code:

 public static boolean isRTL() {
   return isRTL(Locale.getDefault());
 }

 public static boolean isRTL(Locale locale) {
  final int directionality = Character.getDirectionality(locale.getDisplayName().charAt(0));
  return directionality == Character.DIRECTIONALITY_RIGHT_TO_LEFT ||
       directionality == Character.DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC;
 }

 if (isRTL()) {
   // The view has RTL layout
 }
 else {
   // The view has LTR layout
 }

This will work for all Android API lavels.

Answer 3

@cyanide's answer has the right approach but a critical bug.

Character.getDirectionality returns the Bi-directional (bidi) character type. Left-to-right text is a predictable type L and right-to-left is also predictably type R. BUT, Arabic text returns another type, type AL.

I added a check for both type R and type AL and then manually tested every RTL language Android comes with: Hebrew (Israel), Arabic (Egypt), and Arabic (Israel).

As you can see, this leaves out other right-to-left languages, so I was concerned that as Android adds these languages, there might have a similar issue and one might not notice right away.

So I tested manually each RTL language.

• Arabic (العربية) = type AL
• Kurdish (کوردی) = type AL
• Farsi (فارسی) = type AL
• Urdu (اردو) = type AL
• Hebrew (עברית) = type R
• Yiddish (ייִדיש) = type R

So it looks like this should work great:

public static boolean isRTL() {
    return isRTL(Locale.getDefault());
}

public static boolean isRTL(Locale locale) {
    final int directionality = Character.getDirectionality(locale.getDisplayName().charAt(0));
    return directionality == Character.DIRECTIONALITY_RIGHT_TO_LEFT ||
           directionality == Character.DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC;
}

Thanks @cyanide for sending me the right direction!

Answer 4

This will work in all SDKS:

private boolean isRTL() {
    Locale defLocale = Locale.getDefault();
    return  Character.getDirectionality(defLocale.getDisplayName(defLocale).charAt(0)) == Character.DIRECTIONALITY_RIGHT_TO_LEFT;
}

Answer 5

If you're using the support library, you can do the following:

if (ViewCompat.getLayoutDirection(view) == ViewCompat.LAYOUT_DIRECTION_RTL) {
    // The view has RTL layout
} else {
    // The view has LTR layout
}

Answer 6

Native RTL support in Android 4.2

    public static ComponentOrientation getOrientation(Locale locale) 
    {
            // A more flexible implementation would consult a ResourceBundle
            // to find the appropriate orientation.  Until pluggable locales
            // are introduced however, the flexiblity isn't really needed.
            // So we choose efficiency instead.
            String lang = locale.getLanguage();
            if( "iw".equals(lang) || "ar".equals(lang)
                || "fa".equals(lang) || "ur".equals(lang) )
            {
                return RIGHT_TO_LEFT;
            } else {
                return LEFT_TO_RIGHT;
            }
    }