Why is CSVParser is reading the next CSVRecord

Question

Using org.apache.commons.csv.CSVParser I am having a strange behavior.

I am trying to read, line by line, a csv file delimited by ; but my parser is skipping line for an unknown reason.

Here is my code:

public static void main(String[] args) {
    try (
        File file = new File("myFile.csv");
        Reader reader = new BufferedReader(new FileReader(file));
        CSVParser parser = new CSVParser(reader, CSVFormat.DEFAULT.withDelimiter(';'));
    ) {
        if (!parser.iterator().hasNext()) {
            throw new RuntimeException("The file is empty.");
        }
        while(parser.hasNext()) { //<----- This skip a line! 
            console.log(parser.iterator().next().get(0).trim());
        }
    }
}

So my console looks like:

line2
line4
line6
line8
line10
line12

etc...

So my problem is that the CSVParser is skipping a line on parser.hasNext() and it shouldn't.

Is my code wrong? I am pretty sure if I replace the parser with an ArrayList the iterator work as expected... Is this a known bug? If yes can you guys point to a work around or a better library?

Answer 1

The problem you have it that each iteration calls iterator(), which returns a NEW Iterator .

Things are getting weird past this point, since the iterator has a current field storing the current record, and of course the current record of a new iterator is null .

In that case it calls getNextRecord() from CSVParser (source code), thus skipping a line .

If you want to stick with the iterator, just re-use the same instance :

Iterator<CSVRecord> iterator = parser.iterator();

while(iterator.hasNext()) { 
    console.log(iterator.next().get(0).trim());
}