I've tried these values but got the error message.
FARSI
PERSIAN
IRAN
fa_IR
ARABIC
B4X:
java.lang.RuntimeException: Field: ARABIC not found in: java.util.Locale
found it :
B4X:
Dim DeviceLocale As Locale
DeviceLocale.Initialize2("fa", "IR")
Dim jo As JavaObject
jo.InitializeStatic("java.util.Locale").RunMethod("setDefault", Array(DeviceLocale))