What is the difference between creating a locale for en-US and en_US?

Question

I have all my ResourceBundle values in a table and formatted as per requirement. I have to change the languages on the website based on user selection in a drop

Answer 1

"en" is the language code specified by ISO 639. while US is country code specified by 3166.
In Java, the Locale object recognizes the language as languageCode_countryCode (e.g. en_US) and not as languageCode-countryCode.