Date-to-String conversion is a relatively complex parsing operation, not something you can do with a simple cast as you are trying.
You'll have to use a DateFormat. It can be as simple as:
Date d = DateFormat.getDateInstance().parse("09/10/2009");
But this changes the expected date format depending on the locale settings of the machine it's running on. If you have a specific date format, you can use SimpleDateFormat:
Date d = new SimpleDateFormat("d MMM yyyy HH:mm").parse("4 Jul 2001 12:08");
Note that the parse method will always expect one specific format, and will not try to guess what could be meant if it receives a different format.