If you just write a Java programm WITHOUT using any text, your programm can be migrated straightforwardly among different langauge environments. If your programm needs to handle text, say, displaying Time and Currency, you can use java.text. package. Then, your programm will display RMB symbol in Chinese environment and
the dolar sign in English environment. Please check %JAVA_HOME%\jre\lib, under which there exists a file named i18n.jar. This strange name means the word "internationalization" has 18 characters. i18n.jar offers support for Java internationalization.
I strongly encourage using English environment.