code: public void setComparator(final int col, final Comparator comparator) {
  		synchronized (this) {
  			if (comparators == null) {
  				comparators = new HashMap<>();
  			}
  		}
  
  		if (comparator == null) {
  			comparators.remove(col);
  		} else {
  			comparators.put(col, comparator);
  		}
  	}
docs: Sets the comparator for the given column, to enable sorting.
  
  @param col the column to set the comparator on.
  @param comparator the comparator to set.