系统找不到FileWriter指定的路径

Question

I have this code:

private static void saveMetricsToCSV(String fileName, double[] metrics) {
        try {
            FileWriter fWriter = new FileWriter(
                    System.getProperty("user.dir") + "\\output\\" +
                    fileTimestamp + "_" + fileDBSize + "-" + fileName + ".csv"
            );

            BufferedWriter csvFile = new BufferedWriter(fWriter);

            for(int i = 0; i < 4; i++) {
                for(int j = 0; j < 5; j++) {
                    csvFile.write(String.format("%,10f;", metrics[i+j]));
                }

                csvFile.write(System.getProperty("line.separator"));
            }

            csvFile.close();
        } catch(IOException e) {
            System.out.println(e.getMessage());
        }
    }

But I get this error:

C:\\Users\\Nazgulled\\Documents\\Workspace\\Só Amigos\\output\\1274715228419_5000-List-ImportDatabase.csv (The system cannot find the path specified)

Any idea why?

I'm using NetBeans on Windows 7 if it matters...

Answer 1

In general, a non existent file will be created by Java only if the parent directory exists. You should check/create the directory tree:

  String filenameFullNoPath = fileTimestamp + "_"  + fileDBSize + "-" 
        + fileName + ".csv";
  File myFile =  new File(System.getProperty("user.dir")  + File.separator 
        + "output" + File.separator + filenameFullNoPath);
  File parentDir = myFile.getParentFile();
  if(! parentDir.exists()) 
      parentDir.mkdirs(); // create parent dir and ancestors if necessary
  // FileWriter does not allow to specify charset, better use this:
  Writer w = new OutputStreamWriter(new FileOutputStream(myFile),charset);

Answer 2

You can use getParentFile ( Java Doc ) to make sure that the parent directory exists. The following will check that the parent directory exists, and create it if it doesn't.

File myFile =  new File(fileName);
if(!myFile.getParentFile.exists()) {
     myFile.getParentFile.mkdirs();
}

Answer 3

I'd guess that the "output" directory doesn't exist. Try adding:

new File(System.getProperty("user.dir") + File.separator + "output").mkdir();