localization - Java Locale case sensitivity -

I have the following code to display the current locale

  System.out. Println (locale .getDefault ()); System.out.println (new locale ("en_US"));  

produces the above form

  en_us en_us  

How do I create a local frequency that < Code> N_US ?

Edit

I am asking because my resource which is Messages_en_US.properties

 Whenever there are any exceptions during ResourceBundle.getBundle ("Message", the new locale ("en_US")), I ignore trying to set it as the default locale;  

  new locale ("en_US")  

A locale whose language code is "en_us" .

  The new locale ("N", "US")  

is a locale whose code is "en" And its country code is "US" .

Singles say language code: local (public language) (string language)

build a locale with a language code

  This constructor makes the value of language lowercase normal.