Default is 15 minute and 1 hour. Might add a config file to allow customization later.
Update: Android APK attached (1 commit ahead of this tag)
Now you can choose the time period, but there are no error checks yet. Choose between 1, 5, 15, 30, 60, 120, 240, 720, 1440, ...
Some cosmetic improvements were added to the user interface and logging.
Fun fact: This program is only about 100KB if linking dynamically. On statically linked Windows it is almost 26MB.
Un-fun fact: Dynamic linking on Windows needs 35MB of DLLs.