Re: Adding String functions?

["Richard Dettinger" <cujo@xxxxxxxxxx>]

Regards,

Richard D. Dettinger
AS/400 Java Data Access Team

"Biologists have a special word for stability -- dead"

                Larry Wall
                Open Source Developers Journal
                Issue 1, Jan  2000


Larry Loen/Rochester/IBM@IBMUS@midrange.com on 03/12/2001 02:27:34 PM

Please respond to JAVA400-L@midrange.com

Sent by:  owner-java400-l@midrange.com


To:   JAVA400-L@midrange.com
cc:
Subject:  Re: Adding String functions?




Unfortunately, String is both immutable and final.  Final means
you can't subclass it.

There are performance and strategic reasons for this.  The
performance ones are that immutable objects have some
minor optimizations available (at a cost in cluttering up your heap with
nearly identical objects).  The strategic one is that String is
by and large automatically thread safe.   (Note that while the String
_itself_ is thread safe, the variable you have somewhere that
holds the reference to a String is not threadsafe in itself).

The net is, if you want a better String, you'll have to write your
own.  Sorry.

You can also look at StringBuffer, which is mutable (at a cost-
everything is synchronized) but it is at least extendable.


Larry W. Loen  -   Senior Java and AS/400 Performance Analyst
                          Dept HP4, Rochester MN


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