Exporting to CSV/Excel in Java

Question

I'm trying to export data into a CSV file through Java and I've got some code to do it but it doesn't seem to be outputting the CSV file. Could someone tell me what's wrong? What I would like to do is rather than saving the file somewhere, I would like it to be directly exported to the user.

EDIT: Just in case it's not clear, I don't want the file to be saved anywhere but would like it to be outputted automatically to the user i.e. they click export and get the "Run/Save results.csv" window and they open the file. Currently the file is getting saved so I know that the method seems to work, just in the opposite way that I want it to.

public static void writeToCSV(List<Map> objectList) {
    String CSV_SEPARATOR = ",";
    try {
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(
                new FileOutputStream("results.csv"), "UTF-8"));
        for (Map objectDetails : objectList) {
            StringBuffer oneLine = new StringBuffer();
            Iterator it = objectDetails.values().iterator();

            while (it.hasNext()) {
                Object value = it.next();

                if(value !=null){
                    oneLine.append(value.toString());
                    }

                if (it.hasNext()) {
                    oneLine.append(CSV_SEPARATOR);
                }
            }
            bw.write(oneLine.toString());
            bw.newLine();
        }
        bw.flush();
        bw.close();
    } catch (UnsupportedEncodingException e) {
    } catch (FileNotFoundException e) {
    } catch (IOException e) {
    }
}

Solution 1

I would recommend using a framework like opencsv for that. It also does escaping and quoting for you.

Solution 2

If you're not getting errors, check the directory where your code is. Without a specific path, your file is being saved there.

EDIT: Since the file is being saved and you want it to open automatically, use

Runtime.getRuntime().exec("results.csv"); 

(For Windows - opens the csv file in the default application for csv files)

Runtime.getRuntime().exec("open results.csv"); 

(For Mac - opens the csv file in the default application for csv files)

Comments

[WIOijwww]

Hmm, after further investigation I found that no exceptions are being thrown, but the file is getting saved to the harddrive. I would actually rather like it to open up automatically so that upon hitting the "Export" button, the file opens directly, if you know what I mean? I'm sure this is possible as I've done it before but can't for the life of me remember how I did it.

[Eric Hydrick]

@WIOijwww Please edit the question to reflect that you need the file to open automatically.

[Eric Hydrick]

@WIOijwww Your original post made it sound like the file wasn't getting written at all, not that it wasn't opening automatically.

[WIOijwww]

Is this really the best way to do it? I thought Java was platform independent.

[Eric Hydrick]

The string in the exec() method is the system command to be run, i.e. what you'd run from the command-line of that particular OS to open the file.