A java.util.Date doesn't have a format. It's just a date.
When you print it out, e.g. using toString(), it uses a default format, which is what you're seeing. But you have that date.
Date dataFrom = new Date();
dataFrom = df.format("14/05/1994");
I don't think that can be your code because DateFormat.format accepts a Date and returns a String, not the other way around. You might mean df.parse, which would get you the results you describe. But if you take your SimpleDateFormat and use its format method on the Date, then you should get back out 14/05/1994 as you want. A java.util.Date doesn't have a format, though.