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From: Eric Sosman <esosman@ieee-dot-org.invalid>
Newsgroups: comp.lang.java.programmer
Subject: Re: StringBuilder Difficulties
Date: Tue, 28 Jun 2011 21:29:00 -0400
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On 6/28/2011 8:54 PM, Gene Wirchenko wrote:
> Dear Java'ers:
>
>       I am working with StringBuilder now.  I grant that it is faster
> in execution, but it is taking a bunch of my time to get it straight.
> I decided to change my VRString class (call-by-value-result) to
> VRStringB.  Complications ensued.
>
>       The amount of ornamentation required in my code was nasty, so I
> did some simplifying.
>
>       How does one assign a String value to a StringBuilder variable?

     One does not "assign" a reference of type T1 to a reference
of unrelated type T2.  One can, however, create a StringBuilder
whose initial content is the same as that of a given String:

	String str = ...; // non-null
	StringBuilder sbd = new StringBuilder(str);

These are "the same" in the sense that str.length() == sbc.length()
and str.charAt(k) == sbd.charAt(k) for all 0 <= k < str.length().
Also, str.equals(sbd.toString()) returns true.

> [...]
>       Am I missing something about StringBuilder, or is it really this
> difficult to play with?

     You've been advised to read some Java tutorials or textbooks,
and (it seems) have chosen not to follow that advice.  Under the
circumstances, then, I'd have to say StringBuilder is "really this
difficult to play with."

     Perhaps you're "too pressed for time" to learn Java before writing
it.  Okay, yeah, that's reality, shit happens.  But if so, you've been
"pressed for time" for some weeks now, and (I'll wager) have already
wasted more time chasing blind alleys than you would have spent learning
the rudiments of the language.  (A potential infinite regress looms.)

> It would make a lot more sense to me if
> StringBuilder worked more like String does.

     StringBuilder is only of interest because it is mutable, while
String is immutable.  From this fact flow many of the necessary
differences that give you so much trouble, but that others take in
stride.

     Summary: Fer Crissakes, Gene, read the damn' book!

-- 
Eric Sosman
esosman@ieee-dot-org.invalid