min value of float in java is positive why?
Why they chose to name the constants like that is unanswerable (by us) because nobody on SO was in the room when the decision was made.
Besides, knowing the answer to the question is not going to help, because the values of Float.MIN_VALUE and Double.MIN_VALUE won't be changed, no matter how "wrong" they might be. (It would break any existing code that uses these constants, and the Java designers only do that when there is no other viable alternative. Leaving it alone is clearly a viable alternative.)
I suppose, the answer (i.e. the real reason for the decision) might be relevant to people developing brand new programming languages. However, they are going to have to make up their own minds anyway. FWIW, I wouldn't have designed it this way, but that's not relevant.