private static final int REQUEST_EXTERNAL_STORAGE = ;

    private static String[] PERMISSIONS_STORAGE = {

            Manifest.permission.READ_EXTERNAL_STORAGE,

            Manifest.permission.WRITE_EXTERNAL_STORAGE};

    /**

     * 8      * Checks if the app has permission to write to device storage

     * 9      *

     * 10      * If the app does not has permission then the user will be prompted to

     * 11      * grant permissions

     * 12      *

     * 13      * @param activity

     * 14

     */

    public static void verifyStoragePermissions(Activity activity) {

        // Check if we have write permission

        int permission = ActivityCompat.checkSelfPermission(activity,

                Manifest.permission.WRITE_EXTERNAL_STORAGE);

        if (permission != PackageManager.PERMISSION_GRANTED) {

            // We don't have permission so prompt the user

            ActivityCompat.requestPermissions(activity, PERMISSIONS_STORAGE,

                    REQUEST_EXTERNAL_STORAGE);

        }

    }