Writing a String array to a file

Question

I have an array of Strings (in java) with 14534 elements. When I write them to a file (csv), the file stops after 13475 elements (in the middle of a line, but with no special characters that I can see).

I checked with the debugger, the array is indeed filled.

Should I use another method? In c++ I would write binary, but I am unsure on how to do it in java. Could it be a problem with the string not being properbly recognised?

FileWriter writer = new FileWriter("out.csv");

for (int i = 0; i < lines; i++){
    for (int j = 0; j < cols; j++){
        // writer.append(""+i);
        // writer.append("-");
        writer.append(""+numbers[j][i]);
        writer.append(';'); 
    }
    writer.append('\n');
}

The strange thing is, it writes about 12 lines further if I add the code to check the lines (in comments).

Any suggestions on what to try?

Answer 1

You're never closing your writer - I suspect the data's just stuck in a buffer.

Adding a writer.flush() call will probably show it to you - but really you should be using either a try-with-resources statement (if you're using Java 7), or a try/finally statement to always close the writer.

As well as making sure you write all the data to the file, it means you'll also release the file handle...

Answer 2

Flush and/or close the writer before checking the contents of the file. In all likelihood the incomplete output is due to buffering.