question: 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 ; }
target:  Verifies the scheme contains only valid characters as per the URN specification (see NID).