CSVReader treart null as string "null"

Question

I have a input csv like below

firstName,lastName
abdu,null
shah,kha

I am using opencsv and my code is like

File inputFile = new File("input.csv");
CsvSchema schema = CsvSchema.emptySchema().withHeader();
MappingIterator<Map<String, String>> mappingIterator = 
        new CsvMapper().readerFor(Map.class).with(schema).readValues(inputFile);

The first mapping iterator results in map with firstName and lastName as keys. The lastName has value as "null" (quoted string). Is there way by which I could read it as null (without quotes)??

Answer 1

in OpenCSV you can implement your own CSVParser like this:

public static void main(String[] args) throws Exception {
    String csv = "firstName,lastName\n" +
            "abdu,null\n" +
            "shah,kha";

    CSVReader reader = new MyCSVReader(csv);

    String[] nextLine;
    while ((nextLine = reader.readNext()) != null) {
        for (String s : nextLine) {
            System.out.print(s == null ? "NULL" : s);
        }
        System.out.println();
    }
}

private static class MyCSVReader extends CSVReader {
    public MyCSVReader(String csv) {
        super(new StringReader(csv));
        parser = new CSVParser() {
            @Override
            protected String[] parseLine(String nextLine, boolean multi) throws IOException {
                String[] result = super.parseLine(nextLine, multi);
                for (int i = 0; i < result.length; ++i) {
                    if ("null".equals(result[i])) result[i] = null;
                }
                return result;
            }
        };
    }
}