code: public int columnIndex(String columnName) {
          int columnIndex = -1;
          for (int i = 0; i < columnList.size(); i++) {
              if (columnList.get(i).name().equalsIgnoreCase(columnName)) {
                  columnIndex = i;
                  break;
              }
          }
          if (columnIndex == -1) {
              throw new IllegalArgumentException(String.format("Column %s is not present in table %s", columnName, name));
          }
          return columnIndex;
      }
docs: Returns the index of the column with the given name
  
  @throws IllegalArgumentException if the input string is not the name of any column in the table