SAX2: DTDDeclHandler (minimalist position)

Bill la Forge b.laforge at
Wed Mar 31 17:52:18 BST 1999

From: Elliotte Rusty Harold <elharo at>
>>Using objects for constants can also cause problems with persistent
>>data, if you were depending on a singularity and testing with ==.
>This isn't a problem with the syntax I've described because there is only a
>fixed set of objects in which identity comparisons are the same as equality

How do you maintain singularities when deserializing a JavaBean which
contains a reference to one of these objects? 

That is to say, you have a constant which references an object. No problem.

Now you have a bean with a variable which has been assigned the constant
value. No problem.

Now you save the bean. No problem.

Now you deserialize the bean. No problem.

Now you test the value of the variable in the bean with ==. Woops. The test
always returns false.

Conclusion: using objects for constants is great unless you are using Java
Serialization or almost any other kind of persistance.


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