Issue with writing a List into CSV file using CSVWriter

Question

I have the following method to write a list into a CSV file using CSVWriter. Unfortunately, it does not separate them by comma which make them messy when I open it in Excel. How can I modify it?

   private void generateCSV(List<String> dataset) throws IOException {
        CSVWriter writer = null;
        JFileChooser chooser = new JFileChooser();
        chooser.setAcceptAllFileFilterUsed(true);
        if (chooser.showSaveDialog(chooser) == JFileChooser.APPROVE_OPTION) {
            File f = chooser.getSelectedFile();
            String file_name = f.toString();
            if (!(file_name.endsWith(".csv"))) {
                file_name += ".csv";
            }
            writer = new CSVWriter(new FileWriter(f));
            for(int i=0; i< dataset.size(); i++){
                String[] str = new String[] {dataset.get(i)};
                writer.writeNext(str);
            }

        } else {
            return;
        }
        writer.close();
    }

Diogo Rocha · Accepted Answer · 2016-05-01 01:14:26Z

1

You're creating a String[] for each element on your dataset in your for loop and then writing one element per each line with writeNext(). So they are not comma separated because it's just one element per line, using the line separator at the end of each line.

I think that this is what you want. Am I right?

private void generateCSV(List<String> dataset) throws IOException {
    CSVWriter writer = null;
    JFileChooser chooser = new JFileChooser();
    chooser.setAcceptAllFileFilterUsed(true);
    if (chooser.showSaveDialog(chooser) == JFileChooser.APPROVE_OPTION) {
        File f = chooser.getSelectedFile();
        String file_name = f.toString();
        if (!(file_name.endsWith(".csv"))) {
            file_name += ".csv";
        }
        writer = new CSVWriter(new FileWriter(f));
        String[] str = new String[dataset.size()];
        for (int i = 0; i < dataset.size(); i++) {
            str[i] = dataset.get(i);
        }
        writer.writeNext(str);

    } else {
        return;
    }
    writer.close();
}

answered May 1, 2016 at 1:14

Diogo Rocha

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5 Comments

Jacki Over a year ago

Yes Exactly .. Thank you so much ... Appreciate your explanation

Jacki Over a year ago

We I open it as Excel, it is not really distributed since they are supposed to be in 34 columns and 321 rows. Do you see why ? Also it is surrounded by "", is there a way to remove it ?

Diogo Rocha Over a year ago

Try to put sep=, as first line in your .csv file, and then open with Excel.

Diogo Rocha Over a year ago

To remove "" change writer.writeNext(str); to writer.writeNext(str, false);. I think it should work.

Diogo Rocha Over a year ago

Check this superuser post for more options related with open CSV with commas in Excel.

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