question: public static boolean isIdentifier ( String string ) { if ( string == null || string . equals ( "" ) ) { return false ; } return string . matches ( "[A-Za-z0-9_]*[A-Za-z]{1}[A-Za-z0-9_]*" ) ; }
target:  Returns true, if the string matches [A-Za-z0-9_]*[A-Za-z]{1}[A-Za-z0-9_]