Quoting QM <qm300@(protected)>:

> On Tue, May 25, 2004 at 03:39:31PM +0200, Rostislav Svoboda wrote:
> : I'd like to ask you if there's a significant difference in performance
> : between:
> :
> :   String ret = "";
> :   for (count = 0; rs.next(); count++)
> :     ret += rs.getString("column_name");      // result of db query
> :   out.print(ret);
> :
> : and:
> :
> :   for (count = 0; rs.next(); count++)
> :     out.print(rs.getString("column_name");    // result of db query
> :
> : I know I have the extra string which is (theoretically) a slow-down but I
> : don't
> : know anything about the way how tomcat handles with large strings (in my
> : case about 1MB), if is there any limited buffering etc.
>
> 1/ what happens when you load-test the two variations?
>
> 2/ it's not about Tomcat handling strings; it's how the underlying JVM
>   handles strings.
>
> 3/ what happens when you load-test the two variations?
>
> 4/ depends on the JDK; newer compilers /may/ see a repeat string concat
>   ("+" op) and replace w/ StringBuffer under the covers...
>

This is a common psuedo-misconception. Compilers can't do anything with strings
that have a paramter of which the value can only be realized at runtime.

public static String OPTIMIZED = "optimized";

"This can be " + OPTIMIZED + " at compile time to a single string with no
concatenation at runtime"


private String optimized;

"This cannot be " + optimized + " at compile time. It *has* to be evaluated at
runtime because the value isn't available at compile time"


Jake


> 5/ what happens when you load-test the two variations?
>
> But, as always, see #1 for the end-all, be-all answer.
>
> -QM
>
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>
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>
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