You can not use a java keyword in your package declaration.
abstract continue for new switch
assert default if package synchronized
boolean do goto private this
break double implements protected throw
byte else import public throws
case enum instanceof return transient
catch extends int short try
char final interface static void
class finally long strictfp volatile
const float native super while
These keyworkds can not be used.
the syntax of package declaration is
PackageDeclaration:
{PackageModifier} package Identifier {. Identifier} ;
Here Identifiers are any Unicode character that is a "Java letter" or any Unicode character that is a "Java letter-or-digit".
The "Java letters" include uppercase and lowercase ASCII Latin letters A-Z (\u0041-\u005a), and a-z (\u0061-\u007a), and, for historical reasons, the ASCII underscore (_, or \u005f) and dollar sign ($, or \u0024). The $ sign should be used only in mechanically generated source code or, rarely, to access pre-existing names on legacy systems.
Refer
- http://docs.oracle.com/javase/tutorial/java/package/namingpkgs.html
- http://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-IdentifierChars