public static List<String> readUniqueColumnValuesFromDelimitedFile(String filename, 
      int columnNumber, String delimiter) {
    Set<String> values = Sets.newHashSet(
        readColumnFromDelimitedFile(filename, columnNumber, delimiter));
    return Lists.newArrayList(values);
  }
public static List < String > readUniqueColumnValuesFromDelimitedFile ( String filename , int columnNumber , String delimiter ) { Set < String > values = Sets . newHashSet ( readColumnFromDelimitedFile ( filename , columnNumber , delimiter ) ) ; return Lists . newArrayList ( values ) ; }
Returns a list of the unique values in {@code columnNumber} of
{@code filename}. The columns of {@code filename} are delimited
by {@code delimiter}.

@param filename
@param columnNumber
@param delimiter
@return