CMP beans - id

[Demetz Markus]

Hi everybody!

I'm new to CMP Beans, and i want each bean to have a unique id and do the
relationships over id's. But which is the best way to generate id's? I found
the following:

private Integer generatePrimaryKey() {
return new Integer((new Object()).hashCode());
}
is this a good way?
Isn't there another approach to do an autoincrement?

Thanks for any hint!
Markus

 

[Viator]

There is no guarantee that new Object().hashCode() will always give you
unique numbers. Try using a class (some sort of Sequencer) that gives
you a unique integer and increments it by one with every call.

Amit

 

[Bjoern Bredohl]

private Integer generatePrimaryKey() {
return new Integer((new Object()).hashCode());
}

You can use this in jdk 1.5.x
...
setId(java.util.UUID.randomUUID().toString());
...

You can also look for UUID Generator like JUG (http://jug.safehaus.org/Home)

Isn't there another approach to do an autoincrement?

Yes, there is another possibility. The RDB can autoincrement. But if you
have CMR's you get problems.

Björn


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