CsvBindByPosition : value for annotation attribute must be a constant expression

I am trying to read a CSV file whose header position numbers comes from a property file. I get the position number for the fields using @Value. But however I am unable to bind this value as the position for @CsvBindByPosition.

Here is my code :

public class MyPojo {

    @Value(value = "${csv.pojo.refNumber}")
    public static final int test;

    @CsvBindByPosition(position = test)
    private String id;
}

This gives me this error:

The value for annotation attribute CsvBindByPosition.position must be a constant expression

Is there a way to resolve this as my position needs to be read from a property file itself?

As suggested by MWiesner answer, annotation value can't be set in runtime.

What we need is some way to configure the column position mapping in runtime instead.

• MappingStrategy is the interface configure mapping between csv and bean.
• And ColumnPositionMappingStrategy is the implementation ready for use in this case.

import com.opencsv.CSVReader;
import com.opencsv.CSVReaderBuilder;
import com.opencsv.bean.ColumnPositionMappingStrategy;
import com.opencsv.bean.ColumnPositionMappingStrategyBuilder;
import com.opencsv.bean.CsvToBean;
import com.opencsv.bean.CsvToBeanBuilder;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.test.context.SpringBootTest;

import java.io.StringReader;

@SpringBootTest(
        classes = CsvByPositionInRuntimeTest.Pojo.class,
        properties = {"csv.pojo.refNumber=0", "csv.pojo.name=1"}
)
public class CsvByPositionInRuntimeTest {
    // assume 0
    @Value("${csv.pojo.refNumber}")
    private Integer refNumberIndex;
    // assume 1
    @Value("${csv.pojo.name}")
    private Integer nameIndex;

    // or specify column order like 'refNumber,name'
    // this is more readable and easy to maintain
    @Value("${csv.pojo.columnOrder}")
    private String[] columnOrder;

    @Test
    public void parse() {
        CSVReader csvReader = new CSVReaderBuilder(
                new StringReader("""
                        123,david
                        456,terry
                        """)
        ).build();
        ColumnPositionMappingStrategy<Pojo> positionMappingStrategy = new ColumnPositionMappingStrategyBuilder<Pojo>().build();
        // this is just for demo, proper implementation is need for all column index
        positionMappingStrategy.setColumnMapping(refNumberIndex < nameIndex ? new String[]{"refNumber", "name"} : new String[]{"name", "refNumber"});
        // positionMappingStrategy.setColumnMapping(columnOrder);
        positionMappingStrategy.setType(Pojo.class);
        CsvToBean<Pojo> csvModelCsvToBean =
                new CsvToBeanBuilder<Pojo>(csvReader).withMappingStrategy(
                        positionMappingStrategy
                ).build();
        csvModelCsvToBean.parse().forEach(m -> System.out.println("id:%s ,name:%s".formatted(m.refNumber, m.name)));
    }

    public static class Pojo {
        private String refNumber;
        private String name;
    }
}