Java, impossible cast Object to Float.....why?

Why this works:

 Object prova = 9.2;
 System.out.println(prova);
 Double prova2 = (Double) prova;
 System.out.println(prova2);

And this doesn't?

Object prova = 9.2;
System.out.println(prova);
Float prova2 = (Float) prova;
System.out.println(prova2);

I lost 1 hour in my java android application cause of this thing so i had to cast it in a double and than the double in a float or i had an exception