Write the BLE scan data into internal storage

I'm building a simple BLE scanner to scan for particular beacon. Currently, I was able to scan the beacon to get the Major, Minor and Rssi value in the logcat continuously until I hit the stop button. However, I'm still having problem on storing data into my internal storage for the entire rssi value that I have scanned earlier. When I checked my txt file in device file explorer, it only able to capture one rssi value for only one time instead of overall scanning. The code that I used to write the data into internal storage as below. Thank you

      writeButton.setOnClickListener(new View.OnClickListener() {

        @Override

        public void onClick(View view) {
            writeFile();
        }
    });

}

    public void writeFile() {
        String textToSave = inputField.getText().toString();

        try {

            FileOutputStream fileOutputStream = openFileOutput("Tutorial File.txt", MODE_PRIVATE);
            fileOutputStream.write(textToSave.getBytes());
            fileOutputStream.close();

            Toast.makeText(getApplicationContext(), "Text Saved", Toast.LENGTH_SHORT).show();

            inputField.setText("");
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
    }

Check the definition of the openFileOutput function. Somewhere inside there it should call a constructor like this: new FileOutputStream(File file, boolean append).

Make sure the second append parameter is set to true so that new records are appended to the file instead of overwriting the contents.