Re: Persistent field and Persistent properties - difference

From:

Tom Anderson <twic@urchin.earth.li>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 12 Oct 2010 19:32:36 +0100

Message-ID:

<alpine.DEB.1.10.1010121929290.13386@urchin.earth.li>

On Tue, 12 Oct 2010, Lew wrote:

gk wrote:

In JPA Entity classes , I don't understand what is a persistent field
and what is a persistent property ?

I have the following understanding as below

If the Entiry class has NO getter/setter then we call the instance
...
BUT
...
Could you please let me know whether I have understood the terminology
persistent field and persistent property correctly. If not , please
let me know where is the difference between them ?

Lew wrote:

In this case they're synonymous.

Strictly speaking, a "field" is a member variable and a "property" is a
publicly accessible attribute, usually accessed in Java via
get.../set... methods, that behaves to the world like a field but might
actually be implemented differently.

That's a rather loose definition but works all right in practice.

Another point - I don't think you can use JPA without getters and setters for
the entity fields.

You can. You annotate the fields, and the provider accesses them with
reflection or some other mechanism. Some (including myself) consider it
preferable to access via the accessors, because it means you don't have to
have accessors where it's not appropriate (see discussions on getters,
setters and object orientation passim), and you're free to do clever stuff
in them when it is.

Thinking about it, i don't know if this is something the spec guarantees,
or something that implementations happen to support. I'll check.

tom

--
Caps lock is like cruise control for cool.