Java: Change value of a Float object

Question

I have looked inside the javadoc for Float, but there does not seem to be any way to modify the value after construction?

Float f = new Float(1.23f);
[...]
f.setValue(3.14f); // Nothing like this seems to exist...
f = 3.14f; // "f" now points to a new object, not what I want...

Is there a way to change the value of the object? Alternatively, is there another wrapper class available that would allow this?

Answer 1

You cannot change the value of a Float; all of the primitive wrapper classes are immutable. You could create your own (mutable) wrapper class if you want to add this functionality, or take a look at MutableFloat from the Apache Commons.

Answer 2

Float is a value object (immutable object).

It makes no sense to alter direclty its value without reinstantiating a new one with the new value.

Indeed, Float has no concept of Identity, it's just a pure VALUE, thus doesn't need a mutable behaviour.

That could be interest you, to understand the concept:

http://devlicio.us/blogs/casey/archive/2009/02/13/ddd-entities-and-value-objects.aspx