Since you entered this as a feature request, and because I don't know that it's possible to do this from the main search (as opposed to the data explorer), I'm going to post this as an answer:
There are something like, what; 30k tags on SO? A great many of these are synonymous with others, and many cover fairly esoteric things. As an example, the following tags exist: iterator iteration iterate iterative
Someone might add any of those tags to a question that you would otherwise want to show up in your query for "only the java tag". There are hundreds - no, thousands - of other examples of kinds of tags which would render the kind of queries you want to do basically worthless.
You would be better off searching for your desired tags, and leaving off ones you do not want. Prefix the tag with a minus sign to do that.
So, in the search box:
Or in a URL:
The following does not exclusively search but it gets stuff done; getting tags you don't want out.
Add the tags you don't want to your Ignored Tags list under preferences
The unanswered page with [java] search
Placing the blackberry tag in the ignored filter.
No more berries in sight.
Of course remember to remove it from the ignored filter when you are done with it