Move leftover Android files.
Prepend private members with an underscore.
Display target seconds.
Calculate and display remaining seconds.
Add timer state.
Prefer accessors.
Change state to FINISHED when target time is reached.
Provide stop button.
Make Timer.start a no-op if the timer is running.
Style changes.
Update interface even when no timer is running.
Stop the timer when the target time is changed.
Add pause logic.