Android-Files

File root   = Environment.getExternalStorageDirectory();

File dir    =   new File (root.getAbsolutePath() + "/FlightData");
File file   =   new File(dir, "FlightData.csv");
file.delete();
dir.delete();

File dir    =   new File (root.getAbsolutePath() + "/FlightData");
if (!dir.exists())
    dir.mkdirs();

    file = new File(dir, "FlightData.csv");
    FileOutputStream out   =   null;
    try {
        out = new FileOutputStream(file, true);
        out.write(dataString.getBytes());
    }
catch (Exception e) {
    if ( Log.isLoggable(tag, Log.WARN))
        Log.w(tag, "Exception trying to save flight data " + dataString, e);
} finally {
    try {
        if (out !=null) {
            out.flush();
            out.close();
        }
    } catch (IOException e) {
        Log.w(tag, "Exception trying to close flight data", e);
    }
}