Read CSV files with known and unknown columns java

Question

I'm wondering if there is a way to read csv files with known and unknown columns.

for example the column in the first csv file is: id, firstname, lastname, city, country the unknwon columns are city and country

the second csv file is:

id, firstname, lastname, phone number the unknwon column is phone number

The Object that I want to parse into is:

public class Person {

    Long id;
    String firstname;
    String lastname;

    Map<String,String> additionalInfo;

}

the additionalInfo map will contain as keys the 'unknown' columns and the values will be the row value in that column.

Any ideas?

Thanks.

Answer 1

OpenCSV allows you to do something similar to this using @CsvBindAndJoinByName annotation. Taken from the docs :

public class Demonstration {

   @CsvBindByName(column = "index")
   private String index;

   @CsvBindAndJoinByName(column = ".*", elementType = String.class)
   private MultiValuedMap<String, String> theRest;

   // Getters and setters go here
}

The same docs mention a caveat: you have to be careful not to have overlapping patterns if you have multiple @CsvBindAndJoinByName , otherwise the result is undefined.

Answer 2

Had the same situation, wanted to access the unknown column from a CSV file. Here is the solution-

`

public class CSVFileDTO {
@CsvBindByName
private String name;

@CsvBindAndJoinByName(column = ".*", elementType = String.class)
private MultiValuedMap<String, String> theRest;

} `

Way to access theRest column -

    List<CSVFileDTO> resultData;
    MultiValuedMap<String, String> multivaluedMap = resultData.get(0).getTheRest();
    Collection<Map.Entry<String, String>> entries = multivaluedMap.entries();

    for(Map.Entry<String, String> ent : multivaluedMap.entries()){
        entityList.add(ent.getKey());
    }

Answer 3

Check feature 9 of this https://github.com/ozlerhakan/poiji API for reading excel files.

public class MusicTrack {

@ExcelCellName("ID")
private String employeeId;

@ExcelCellName("AUTHOR")
private String author;

@ExcelCellName("NAME")
private String name;

@ExcelUnknownCells
private Map<String, String> unknownCells;}