Can't read lines from a text file

Question

I have a method like this:

    public int getIncrement() {

    String extractFolder = "/mnt/sdcard/MyFolder";
    boolean newFolder = new File(extractFolder).mkdir();
    int counter = 0; 

    try {
        File root = new File(extractFolder); 
        if (root.canWrite()){
            File gpxfile = new File(root, "gpxfile.txt");
            FileWriter gpxwriter = new FileWriter(gpxfile);
            BufferedWriter out = new BufferedWriter(gpxwriter);

            Scanner scanner = new Scanner(new FileInputStream(gpxfile.getAbsolutePath()), "UTF-8");
            Log.i("PATH: ", extractFolder + "/gpxfile.txt");

           while(scanner.hasNextLine()) {
               String inc = scanner.nextLine(); 
               counter = Integer.parseInt(inc);
               Log.i("INSIDE WHILE: ", Integer.toString(counter)); 
           }
            counter++;
            out.write(Integer.toString(counter));
            out.close();
        }
    } catch (IOException e) {
        Log.e("GEN_PCN: ", "Could not write file " + e.getMessage());
    }
    return counter;  
}

What I am trying to accomplish is returning the content of this file, and increment the integer by 1. But it seems that I can't get in the while loop, because LogCat doesn't print out anything. Yes, am sure that the path is correct.

Answer 1

I guess the constructor of FileWriter gpxwriter has already blanked out the file by the time the Scanner is created, so the file is empty and hasNextLine returns false . Why do you open a file for writing when you want to read it?

Answer 2

From what I can tell the file doesn't exist. Try adding gpxfile.createNewFile()

To get a little more in depth, creating a File instance, does not create a file on the file system.

So, this line -> File gpxfile = new File(path, filename);

is not sufficient to create the file on the sd card. You must follow it with

gpxfile.createNewFile() which quoting the docs says:

Atomically creates a new, empty file named by this abstract pathname if and only if a file with this name does not yet exist. The check for the existence of the file and the creation of the file if it does not exist are a single operation that is atomic with respect to all other filesystem activities that might affect the file.

Answer 3

OK I MARK YOUR FILE NAME

Just add a BACKSLASH in extractFolder at END

                                            v
                                            v
                                            v
String extractFolder = "/mnt/sdcard/MyFolder/";
                                            ^ // <---   HERE
                                            ^
                                            ^

Because File gpxfile = new File(root, "gpxfile.txt"); doesn't have BackSlash / as Log have

---

Just try Once Following:

while(scanner.hasNextLine()) {
      String inc = scanner.nextLine(); 
      //       //   counter = Integer.parseInt(inc);
      Log.i("INSIDE WHILE: ", inc);
      System.out.println("Next Line ::"+inc);  //  Also check this
}