I am making an alarm app, that should be able to show time until next alarm. At my disposal, I have current time, and Hours:minutes:AM/PM values, and day of the week, for example 3:15 AM Tue. How can I compute this ? All I am interested in is to print it like this: 07h 35m. 

What I've done, is I tried to convert it to date, then convert it back to millis, and do some math behind, but it is not working, I keep getting wrong results.

EDIT:

My problem is, that I have my time set by my custom views, like 3:15 AM Tuesday. I need to convert it to closest Date object. So for example when today is Tuesday, and it's 2:00 AM I will just edit the time, but when today is Friday, I would need to add some days and time.