JAVA write new row to .CSV file

Question

How can I write a new row of data to a .CSV file that already has data in it. So far my code just clears the file and doesn't actually write anything?

            BufferedReader br = null;
        BufferedWriter bw = null;
        String fileString = "patients.csv";
        String fileLine = "";

        File file = new File(fileString);
        br = new BufferedReader(new FileReader(file));
        FileWriter fw = new FileWriter(fileString);
        bw = new BufferedWriter(fw);

        while((fileLine = br.readLine()) != null){

            bw.write(fileLine);
        }


        br.close();
        bw.close();

What are you actually trying to do? Can you show input and expected output? — Tim Biegeleisen, Sep 27 '16 at 04:36
I want to write a new line of data to an existing .CSV file. The input comes from multiple JTextFields — Samuel Hornby, Sep 27 '16 at 04:40

score 1 · Accepted Answer · answered Sep 27 '16 at 04:44

1

specify true in the constructor java FileWriter to know that the true and append be added to the end of the file if you place it does not overwrite information

FileWriter fw = new FileWriter(fileString,true);

answered Sep 27 '16 at 04:44

DarkFenix

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score 0 · Answer 2 · answered Sep 27 '16 at 04:36

If you want to append to a file using FileWriter then use this Constructor

As per Javadocs

Constructs a FileWriter object given a File object. If the second argument is true, then bytes will be written to the end of the file rather than the beginning.

But, back to your code, you will only need to write new data to the FileWriter and not rewrite existing data.

JAVA write new row to .CSV file

2 Answers2