Jeremy had already given you the clue to get started.
Since you need the current date, your best bet would be the system date, that will always give you today's (current) date.
Using the java.util.GregorianCalendar class, you're able to get this current date. Hint: look at its constructor.
Your second part involves setting your time components, namely HOUR, MINUTE & SECOND into 0s. So there must be some way (methods) that can help you to do the setting jobs.
The API for GregorianCalendar will be able to help you get all the pieces together into your desired codes.