good practive to have write-once setters?

[Elhanan]

hi..

i have a few java beans which at first didn't have no-ops consturtctors
(as they were sopoused to be created by spring), but i need also to
create them by code, so i thought about using factories. for this i'll
need to have them no-op constuctors

however since a few of these properties are to be used in map hashcodes
and equels implementaitons, i had check in setters if they are allready
been set before, and if so throw an excption..

is this a good thing?

 

[opalpa]

That does not seem to be a good thing. Why does factory mean you need
no argument constructor?

Opalinski
(e-mail address removed)
http://www.geocities.com/opalpaweb/

 

[Manish Pandit]

The best way (again, based on the limited context of your situation) to
have a class with accessors and no mutators will be to initialize the
arguments with the constructor. Your constructor can accept the
arguments and initialize them, and the class will expose no mutators,
making it read only.

-cheers,
Manish

 

[Elhanan]

becouse the factory calls an interface typeIdentier, to help it decide
which class to inititize, the class implementing the typeIdentier sends
back the actuall class itself, which i then use newInstance to create a
new instance of it (i don't have newInstance with paramters).

for examplle

i have PosSource,and StandardSource, both share the same interface
source,

the typeIdentifier looks sorta like this:

case ..

return PosSource.class
case
return StandardSource.class

 

[Lew]

The best way (again, based on the limited context of your situation) to
have a class with accessors and no mutators will be to initialize the
arguments with the constructor. Your constructor can accept the
arguments and initialize them, and the class will expose no mutators,
making it read only.

-cheers,
Manish

And declare the members "final" so that they cannot be reset.

This is a step toward making the class immutable, and immutable is often a
Good Thing.

- Lew

 

[opalpa]

i don't have newInstance with paramters

What you do have is getConstructor(...).newInstance(...)

Cheers.
Opalinski
(e-mail address removed)
http://www.geocities.com/opalpaweb/