How to display the current pair in android?

Question

Java

Hello.
The task is to display in the application which pair is currently running.
For example -
the time is 9:00 > the application shows that the first couple has started;
the time is 10:30 > the app shows that the first couple has ended
, etc.
I also want to do a countdown to the end of the couple. Tell me, please, how to implement, which classes are better to use?