+1
(thanks for the clarification!)
Lloyd L Chambers wrote:
> +1
>
> On Mar 21, 2008, at 1:32 PM, Bill Shannon wrote:
>> Ken Paulsen wrote:
>>> Lloyd, Bill and others:
>>> To make sure I understand correctly, let me see if I can repeat back
>>> what you're saying...
>>> If you define a constant (public static final), for example:
>>> public static final String C = "hello";
>>> ...then another class references that code, it will be contained in
>>> bytecode (i.e. it won't look at the orginal C). In other words, if
>>> you change "hello" to "goodbye" w/o recompiling all classes using C,
>>> you'll still have "hello" in those classes that weren't recompiled.
>>
>> Correct.
>>
>>> However... if you define your "constant" like this:
>>> private static String getC() { return "hello" }
>>> public static final String C = getC();
>>> Or even:
>>> public static final String C;
>>> static { C = "hello"; }
>>> Then code refering to "C" *WILL* refer back to the class instead of
>>> keeping it local via bytecode. This is arguably not a constant now
>>> (although public static final, it cannot be "inlined" by other
>>> .class code). In other words, if you change "hello" to "goodbye" and
>>> ONLY compile the class which defines C, it will still be seen in ALL
>>> classes referencing C (i.e. no more "hello" anywhere).
>>
>> Correct.
>>
>>> Is that right? And if so, what is your recommendation or design
>>> pattern that we should follow? It was not clear (to me) from the
>>> email exchange. Which if these should be preferred:
>>> * Enum
>>> * "public static final" initialized via a static method
>>> * "public static final" initialized via a static block (probably the
>>> same thing to the JVM??)
>>> * No "public static final" use static getter method instead
>>> * or ??
>>
>> Don't use Strings for enumerated values that aren't externally defined
>> (e.g., in a protocol spec). Use enums.
>>
>> If the constant is externally defined (e.g., MIME types, charset
>> names, etc.), feel free to use, e.g,
>>
>> public static final String PLAIN_TEXT = "text/plain";
>>
>> If the constant represents a default, and you want the ability to
>> change the default in the future, provide the value via a public
>> getDefaultFoo() method.
>>
>> While the static block initializer works, I'm not sure that's ever
>> the right answer.
>>
>> Maybe we should look at a few examples of where you run into this issue?
>> Some real examples might help us create and understand the general
>> rules.
>>
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>
> ---
> Lloyd L Chambers
> lloyd.chambers_at_sun.com
> Sun Microsystems, Inc
>
>
>
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