Java浮动到双 - 上限和下限？

As most here will know, double -> float incurs a loss in precision. This means, multiple double values may be mapped to the same float value. But how do I go the other way? Given a normal (I'm not caring about the extreme cases) float, how do I find the upper and lower value of double precision that are still mapped to the same float?As most here will know, double -> float incurs