Creating and writing a file android

Question

Im trying to write to a file in my android app.

I dont think its creating the file though.

is the code to correct?
if it is, how do I locate the file on my phone? Is it hidden?

The code resides in an Activity fragment

        String FILENAME = "alarmStatus";
        FileOutputStream fos;
        try {
            fos = getActivity().openFileOutput(FILENAME, MODE_PRIVATE);
            fos.write("Hello".getBytes());
            fos.close();


        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

Are you getting an error? Have you stepped through the code? What does the documentation say? Asking a question here should be your fifth or sixth step, not your second (after writing and executing the code.) — Dave Swersky, Aug 13 '14 at 22:52
Hi Dave thanks for your reply. At first I was getting "Read only File System" errors when I tried to introduce a directory to write the file to. Ive read thedeveloper docs and this I tried to follow their example. http://developer.android.com/guide/topics/data/data-storage.html#filesInternal — mogoli, Aug 13 '14 at 22:59
08-14 00:01:20.847: W/System.err(21797): java.io.IOException: open failed: EROFS (Read-only file system) — mogoli, Aug 13 '14 at 23:02
Trouble is I dont know if the file where the file is, I use a file manager app to try and find it but I cant see it. I also dont know how to change the file permissions upon creation. — mogoli, Aug 13 '14 at 23:03
You won't be able to find the file using a file manager app as `openFileOutput(...)` creates a file in internal storage which is restricted to your app. I can't think of a valid reason why you're getting an error indicating the file system is read-only though. That method call doesn't require any special permissions. — Squonk, Aug 13 '14 at 23:50
Did you try just openFileOutput() instead of getActivity().openFileOutput()? — Mobile Developer, Aug 14 '14 at 00:02
@MobileDeveloper : The `Fragment` class doesn't have an `openFileOutput` method. That method is only available to classes which extend `ContextWrapper` or `Context`. — Squonk, Aug 14 '14 at 00:06
Your app needs file writing permissions to write a file. http://stackoverflow.com/questions/2121833/permission-to-write-to-the-sd-card — Dave Swersky, Aug 14 '14 at 13:48
@Squonk, thanks for your comment, do you know the write way to write and read to a file in a fragment please? — mogoli, Aug 14 '14 at 22:53

score 0 · Accepted Answer · answered Aug 14 '14 at 23:28

I think Ive found a solution, abit long winded but it does work, please poke at it :)

      File file = new File(getActivity().getFilesDir() +"alarmStatus.txt");
        OutputStream out = null;

        try {
            out = new BufferedOutputStream(new FileOutputStream(file));
            out.write("Hello".getBytes());
           out.close();

        }catch(Exception e){

        }

        BufferedReader in =null;

        try{
            FileInputStream fis = new FileInputStream(file);
            in = new BufferedReader(new InputStreamReader(fis));
            System.out.println("File Output is "+in.readLine());


        }catch(Exception e){

        }

Creating and writing a file android

1 Answers1