convert string value to charsequence and show it in notification in android
<p>I want to show the result of this function in notification.</p>

<pre><code>public class TimerService extends Service {
    public String timeString;
... // service methodd
public class CountingDownTimer extends CountDownTimer{
             public CountingDownTimer(long millisInFuture, long countDownInterval) {
            super(millisInFuture, countDownInterval);
        }

        @Override
        public void onTick(long leftTimeInMilliseconds) {

            timeString = String.format("%02d", 5000/ 60)
                    + ":" + String.format("%02d", 5000% 60);
                ...
        }
...// at the end of TimerService class
                    notification = new NotificationCompat.Builder(this)
                    .setContentText(timeString).build();
</code></pre>

<p>but unfortunately nothing(null) show in the notification. what can I do? how can I convert String value to char sequence? </p>