Ostrava
From APIDesign
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| - | [[Ostrava]] is 3rd largest town in Czech Republic. I | + | [[Ostrava]] is 3rd largest town in Czech Republic. I visited [[wikipedia:Ostrava|Ostrava]]'s [http://java.cz/article/czjug-ostrava-brezen-2011 JUG meeting] on Mar 2nd, 2011. |
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| + | [[Image:Ostrava-jug.jpg]] | ||
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| + | I talked about [[paradox]]es, in a shorter version of the [[ParadoxesVideo]]. | ||
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| + | [[Image:OstavaAJa.jpg]] | ||
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| + | Those who stopped by (and there was about 90 listeners) got a chance to win one copy of [[TheAPIBook]] by finding an answer to a simple quiz: Can you write a code that throws ''NullPointerException'' directly from the following ''Interval'' class? | ||
<source lang="java" snippet="interval.api"/> | <source lang="java" snippet="interval.api"/> | ||
| - | I tried to follow all the [[good]] advices of [[TheAPIBook]]. I made the class final, I check for wrong arguments. My internal state is immutable. I guard myself against mutability of ''Date''. Is it | + | When writing the code I tried to follow all the [[good]] advices of [[TheAPIBook]]. I made the class final, I check for wrong arguments. My internal state is immutable. I guard myself against mutability of ''Date''. Is it enough to write bullet proof code? |
Indeed it is not. As about five people during my [[Paradox]]es talk in [[Ostrava]] found out (and as few of you commented online), one can subclass ''Date'' and override ''clone'' method to return '''null''': | Indeed it is not. As about five people during my [[Paradox]]es talk in [[Ostrava]] found out (and as few of you commented online), one can subclass ''Date'' and override ''clone'' method to return '''null''': | ||
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<source lang="java" snippet="interval.exploit"/> | <source lang="java" snippet="interval.exploit"/> | ||
| - | This is an interesting way to break many solid [[API]]s. The trick has been invented by the [[HPAPIFest09|HP guys]] when they played their [[HPAPIFest09]]. I am glad [[Ostrava]] discovered the magic as well. | + | This is an interesting way to break many solid [[API]]s. The trick has been invented by the [[HPAPIFest09|HP guys]] when they played their [[HPAPIFest09]]. I am glad [[Ostrava]] discovered the magic as well. I am glad I could visit [[Ostrava]]'s JUG and talk about my two favorite topics: [[API]] design and [[NetBeans]] platform. |
Revision as of 12:26, 7 March 2011
Ostrava is 3rd largest town in Czech Republic. I visited Ostrava's JUG meeting on Mar 2nd, 2011.
I talked about paradoxes, in a shorter version of the ParadoxesVideo.
Those who stopped by (and there was about 90 listeners) got a chance to win one copy of TheAPIBook by finding an answer to a simple quiz: Can you write a code that throws NullPointerException directly from the following Interval class?
does not exists: interval.api
When writing the code I tried to follow all the good advices of TheAPIBook. I made the class final, I check for wrong arguments. My internal state is immutable. I guard myself against mutability of Date. Is it enough to write bullet proof code?
Indeed it is not. As about five people during my Paradoxes talk in Ostrava found out (and as few of you commented online), one can subclass Date and override clone method to return null:
does not exists: interval.exploit
This is an interesting way to break many solid APIs. The trick has been invented by the HP guys when they played their HPAPIFest09. I am glad Ostrava discovered the magic as well. I am glad I could visit Ostrava's JUG and talk about my two favorite topics: API design and NetBeans platform.
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