public static void hideNavigationBar() {
        try {
            Process proc = null;
            String ProcID = "79"; // HONEYCOMB AND OLDER
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH)
                ProcID = "42"; // ICS AND NEWER
            proc = Runtime.getRuntime().exec(
                    new String[] { "su", "-c", "service call activity " + ProcID + " s16 com.android.systemui" });
            proc.waitFor();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void showNavigationBar() {
        Process proc = null;
        try {
            proc = Runtime.getRuntime().exec(new String[] { "su", "-c", "am startservice -n com.android.systemui/.SystemUIService" });
            proc.waitFor();
        } catch (Exception e) {
            // do nothing
        }
    }