How to keep time in sync

Question

Hello everybody. I am developing an application that runs on Android phones. These phones must be time synchronized. For this, I am using the GuerrillaNTP client. It works great, but sometimes the internal clock the app uses "jumps" forward one second (sometimes two seconds) and then back to normal time. How can I filter those jumps? All NTP packets come with maximum precision, but it keeps doing the same from time to time.
I have not found any code for a precision clock on Android.
Thanks in advance for the tips.