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

Question

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

Answer 1

Because you are relying on autoboxing when you wrote

Object prova = 9.2; 

If you want it to be a Float, try

Object prova = 9.2f; 

Remember that java.lang.Float and java.lang.Double are sibling types; the common type is java.lang.Number

If you want to express a Number in whatever format, use the APIs, for example Number.floatValue()

Answer 2

Because prova is a Double, and Double is not a subtype of Float.

Either you could start with a float literal: 9.2f (in which case prova would actually be a Float) or, you could it like this:

Float prova2 = ((Double) prova).floatValue();