Saving multiple files with the same name to android internal storage and displaying them in a list view in a different activity

Question

Trying to get a list of files so that I can name the next file based on how many are already there. The idea is similar to downloading multiple files with the same name. Eg:

filename.txt

filename(1).txt

filename(2).txt

etc...

this is the current method I am using, which returns a list of strings.

private List<String> getFilenames(String path) {

    File files = new File(path);

    FileFilter filter = new FileFilter() {

        private final List<String> exts = Arrays.asList("json");

        @Override
        public boolean accept(File pathname) {
            String ext;
            String path = pathname.getPath();
            ext = path.substring(path.lastIndexOf(".") + 1);
            return exts.contains(ext);
        }
    };

    final File [] filesFound = files.listFiles(filter);
    List<String> list = new ArrayList<String>();
    if (filesFound != null && filesFound.length > 0){
        for (File file : filesFound){
            list.add(file.getName());
        }
    }
    return list;

Once I have the list I'm thinking I can use the list.length method to figure out which number I need to put in the filename.

Here is where I am creating the file.

            JSONObject jsonToSave = createJSONObject();

            String filepath = "fileStorage";

            List<String> filenames = getFilenames(filepath);

            int filenameNumber = filenames.size() + 1;

            ContextWrapper contextWrapper = new ContextWrapper(getApplicationContext());
            File directory = contextWrapper.getDir(filepath, Context.MODE_PRIVATE);

            filename = "newAssessment(" + filenameNumber + ").json";
            internalFile = new File(directory , filename);

            try {
                FileOutputStream fos = new FileOutputStream(internalFile);
                OutputStreamWriter osw = new OutputStreamWriter(fos);
                osw.write(jsonToSave.toString());
                osw.close();

                Context context = getApplicationContext();
                CharSequence text = "Assessment saved!";
                int duration = Toast.LENGTH_LONG;

                Toast toast = Toast.makeText(context, text, duration);
                toast.show();
            }
            catch (IOException e){
                e.printStackTrace();
            }

the createJSONObject just creates a json object with the data that needs to be saved.

I can confirm the the application is getting to the Toast that is in the try block after the OutputStreamWriter is closed, so the file is saving.

The problem that I am having is when trying to populate a ListView in another activity with some of the data from the files, nothing appears on listview. I have tested with success reading a single file.

I'm using the same getFilenames method as above, then using FileInputStream to read the data from the files, parse it into a json object, add some fields from each file to an array, and then update an android listview with the array.

Heres the code:

    filenames = getFilenames(filepath);

    ContextWrapper contextWrapper = new ContextWrapper(getApplicationContext());
    File directory = contextWrapper.getDir(filepath, Context.MODE_PRIVATE);


    for (String filename : filenames) {

        internalFile = new File(directory, filename);
        try {
            FileInputStream fis = new FileInputStream(internalFile);
            DataInputStream in = new DataInputStream(fis);
            BufferedReader br = new BufferedReader(new InputStreamReader(in));

            String assessmentDate = "";
            String orchard = "";
            String strLine;
            int dataCounter = 0;

            while ((strLine = br.readLine()) != null) {
                myData = myData + strLine;
                try {
                    JSONObject object = new JSONObject(myData);
                    assessmentDate = object.getString("assessmentDate");
                    orchard = object.getString("orchard");
                } catch (JSONException e) {
                    e.printStackTrace();
                }
                data.add(dataCounter, assessmentDate + " : " + orchard);

                dataCounter++;
            }
            in.close();
        } catch (IOException e) {
            e.printStackTrace();
        }


    }
    LVAssessments.setAdapter(new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, data));

Any help is much appreciated, thank you.