bitmapToFile.java

public static File bitmapToFile(Bitmap bitmap) {
    // File name like "image.png"
    SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmss");
    String fileNameToSave = sdf.format(new Date());
    //create a file to write bitmap data
    File file = null;
    try {
        file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + File.separator + fileNameToSave + ".png");
        file.createNewFile();

        //Convert bitmap to byte array
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.PNG, 0, bos); // YOU can also save it in JPEG
        byte[] bitmapdata = bos.toByteArray();

        //write the bytes in file
        FileOutputStream fos = new FileOutputStream(file);
        fos.write(bitmapdata);
        fos.flush();
        fos.close();
        Log.e("exists", file.exists() + "");
        return file;
    } catch (Exception e) {
        e.printStackTrace();
        return file; // it will return null
    }
}