question: private static String listToString ( List < Integer > list ) { Collections . sort ( list ) ; StringBuilder builder = new StringBuilder ( ) ; for ( int i = 0 ; i < list . size ( ) ; i ++ ) { Integer column = list . get ( i ) + 1 ; if ( i < list . size ( ) - 2 ) { builder . append ( column ) ; builder . append ( ", " ) ; } else if ( i == list . size ( ) - 2 ) { builder . append ( column ) ; builder . append ( AND ) ; } else { builder . append ( column ) ; } } return builder . toString ( ) ; }
target:  Converts the integer list to a string where the entries are separated by "," and "and".