Re: is class file backward compatible

Thanks Joe. Well put. Now, for a newbie Thread.destroy() sound like a
logic choice to terminate a thread hehehe.

"Joe Sam Shirah" <joe_sam@xxxxxxxxxxxxx> wrote in message
news:<mailman.11084.1237570342.26163.java400-l@xxxxxxxxxxxx>...

Well, it seems to me that with:

So, what will happen if the class, that compiled in the older

version of

java complier, has a method that is fully deprecated in the new

version

of JVM?

the question went from reasonable for a newbie, to magical. There is
no product that can guarantee that future versions will *always* run

older

things. Feel free to argue, but someone can always come up with

scenarios

(even if extreme) that wouldn't work.

So, the answer is that you can normally, reasonably expect

previously

compiled classes to run in a later JVM. That's much more than most

can

promise.

*Generally* deprecated is not a problem, but note that some of

these say

"expected to be removed at some point." Now I'll give a real-life

example:

Thread.destroy() was never a good idea and actually was never
implemented. At some point, it was changed to throw

NoSuchMethodError. No

problem, right? No knowledgeable programmer would ever have used it

anyway.

Well, a sometime client of mine, who thinks they can save money by
paying four (and sometimes more) offshore programmers each a third of

my

rate, assigned them to a project in which threads were a perfect fit.

They

"delivered" a mess which depended on destroy() for cleanup. Now, it

didn't

do anything anyway, but under 1.4, it just didn't do anything so the

program

ran (if you can call it that.) But try to run it under 1.5 and, you

guessed

it: NoSuchMethodError. BTW, the client routinely gets to pay me or

others

to clean up after this group while the users suffer non-production

quality

applications. But, "it's a corporate direction."

Another example was on another list yesterday. Someone wanted
performance gains in JSF, but couldn't go to JSF 1.2 because one (of

an

extremely large number) of their dependencies was Apache Beehive,

which

won't play nice with 1.2.

To repeat, the point is you can normally, reasonably expect

previously

compiled classes to run in a later JVM, but there are always

exceptional

conditions.


Joe Sam

Joe Sam Shirah - http://www.conceptgo.com
conceptGO - Consulting/Development/Outsourcing
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----- Original Message -----
From: "Lim Hock-Chai" <Lim.Hock-Chai@xxxxxxxxxxxxxxx>
To: <java400-l@xxxxxxxxxxxx>
Sent: Friday, March 20, 2009 12:47 PM
Subject: Re: is class file backward compatible

Interesting. Thanks.

"James Perkins" <jrperkinsjr@xxxxxxxxx> wrote in message
news:<mailman.11055.1237566399.26163.java400-l@xxxxxxxxxxxx>...

Deprecated methods for more of a "please don't use me" rather than

a

"you

can't use me". They really only show themselves at compile time as

warnings

(or you IDE).

So, you should be fine.
--
James R. Perkins


On Fri, Mar 20, 2009 at 09:13, Lim Hock-Chai
<Lim.Hock-Chai@xxxxxxxxxxxxxxx>wrote:

So, what will happen if the class, that compiled in the older

version of

java complier, has a method that is fully deprecated in the new

version

of JVM?

"David Gibbs" <david@xxxxxxxxxxxx> wrote in message
news:<mailman.11041.1237564455.26163.java400-l@xxxxxxxxxxxx>...

Lim Hock-Chai wrote:

can a class that created using a lower version of java

compiler

run

on a

higher version of JVM?

Yes, this should be possible without a problem.

david



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