Is there any difference between these two statements?

Question

1. float ff = 1.2f;
2. Float fo = new Float(1.2f);
3. double fg = 3.2d;
4. Double fh = new Double(2.1d);

Can I use '=' between the (1) and (3) or between the (2) and (4)??

Answer 1

Yes.

1. Makes a plain old data type (AKA a primitive type) called "float."
2. Makes a Java Object called Float that holds that value that happens to be identical to (1)

Responding to the edit questions:

You will see

1. "possible loss of precision" message if you try ff = fg.
2. "incompatible types" if you try fo = fh.
3. fg = ff will work fine (the float fits in a double).
4. fh = fo will still give you an "incompatible types".