boolean isValidScheme(String scheme){
  for (int i=0; i < scheme.length(); i++) {
    char ch=scheme.charAt(i);
    if (URIHelper.isAlpha(ch) || URIHelper.isNumeric(ch) || ch == '-') {
      continue;
    }
    return false;
  }
  return true;
}

boolean isValidScheme ( String scheme ) { for ( int i = 0 ; i < scheme . length ( ) ; i ++ ) { char ch = scheme . charAt ( i ) ; if ( URIHelper . isAlpha ( ch ) || URIHelper . isNumeric ( ch ) || ch == '-' ) { continue ; } return false ; } return true ; }
verifies the scheme contains only valid characters as per the urn specification ( see nid ) .
