Ostrava - Revision history

JaroslavTulach at 09:31, 13 April 2011

2011-04-13T09:31:31Z

←Older revision		Revision as of 09:31, 13 April 2011
Line 20:		Line 20:

	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.		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.
		+
		+	[[Category:Video]]

JaroslavTulach at 09:16, 13 April 2011

2011-04-13T09:16:42Z

←Older revision		Revision as of 09:16, 13 April 2011
Line 4:		Line 4:
	[[Image:OstavaAJa.jpg\|right\|thumb]]		[[Image:OstavaAJa.jpg\|right\|thumb]]

-	I talked about [[paradox]]es, in a shorter version of the [[ParadoxesVideo]]. Here is the video ~~from~~ the presentation (only for Czech speakers):	+	I talked about [[paradox]]es, in a shorter version of the [[ParadoxesVideo]]. Here is the video taken during the JUG presentation. It is probably only useful for Czech speakers, as I spoke Czech. I have to mention that I admire the way the slides and the view of the speaker are merged together. Good job [[Ostrava]] JUG! I am glad I could stop by.

	{{#ev:vimeo\|21430542}}		{{#ev:vimeo\|21430542}}

JaroslavTulach at 09:12, 13 April 2011

2011-04-13T09:12:07Z

←Older revision		Revision as of 09:12, 13 April 2011
Line 1:		Line 1:
	[[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.		[[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.

-	[[Image:Ostrava-jug.jpg]]	+	[[Image:Ostrava-jug.jpg\|right\|thumb]]
		+	[[Image:OstavaAJa.jpg\|right\|thumb]]

-	I talked about [[paradox]]es, in a shorter version of the [[ParadoxesVideo]].	+	I talked about [[paradox]]es, in a shorter version of the [[ParadoxesVideo]]. Here is the video from the presentation (only for Czech speakers):
		+
		+	{{#ev:vimeo\|21430542}}

-	~~[[Image:OstavaAJa.jpg]]~~

	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?		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?

JaroslavTulach at 12:26, 7 March 2011

2011-03-07T12:26:10Z

←Older revision		Revision as of 12:26, 7 March 2011
Line 1:		Line 1:
-	[[Ostrava]] is 3rd largest town in Czech Republic. I~~'ll be in~~ [[wikipedia:Ostrava\|Ostrava]] at [http://java.cz/article/czjug-ostrava-brezen-2011 JUG meeting] on Mar 2nd, 2011. I~~'ll talk~~ about [[paradox]]es, in a shorter version of the [[ParadoxesVideo]]. ~~Stop~~ by and ~~get~~ a chance to win [[TheAPIBook]]~~. I am not sure what will be the final quiz~~ to ~~win [[TheAPIBook]], but I'd suggest following one~~: Can you write a code that throws ''NullPointerException'' directly from the following ''Interval'' class?	+	[[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.
		+
		+	[[Image:Ostrava-jug.jpg]]
		+
		+	I talked about [[paradox]]es, in a shorter version of the [[ParadoxesVideo]].
		+
		+	[[Image:OstavaAJa.jpg]]
		+
		+	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 ~~really~~ bullet proof code?	+	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''':
Line 9:		Line 17:
	<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.

JaroslavTulach at 19:22, 3 March 2011

2011-03-03T19:22:01Z

←Older revision		Revision as of 19:22, 3 March 2011
Line 1:		Line 1:
-	[[Ostrava]] is 3rd largest town in Czech Republic. I'll be in [[wikipedia:Ostrava\|Ostrava]] at [http://java.cz/article/czjug-ostrava-brezen-2011 JUG meeting] on Mar 2nd, 2011. I'll talk about [[paradox]]es, in a shorter version of the [[ParadoxesVideo]]. Stop by and get a chance to win [[TheAPIBook]]. I am not sure what will be the final quiz to win [[TheAPIBook]], but I'd suggest following one: Can you write a code that ~~throw~~ ''NullPointerException'' directly from the following ''Interval'' class?	+	[[Ostrava]] is 3rd largest town in Czech Republic. I'll be in [[wikipedia:Ostrava\|Ostrava]] at [http://java.cz/article/czjug-ostrava-brezen-2011 JUG meeting] on Mar 2nd, 2011. I'll talk about [[paradox]]es, in a shorter version of the [[ParadoxesVideo]]. Stop by and get a chance to win [[TheAPIBook]]. I am not sure what will be the final quiz to win [[TheAPIBook]], but I'd suggest following one: 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"/>

JaroslavTulach at 19:21, 3 March 2011

2011-03-03T19:21:15Z

←Older revision		Revision as of 19:21, 3 March 2011
Line 1:		Line 1:
	[[Ostrava]] is 3rd largest town in Czech Republic. I'll be in [[wikipedia:Ostrava\|Ostrava]] at [http://java.cz/article/czjug-ostrava-brezen-2011 JUG meeting] on Mar 2nd, 2011. I'll talk about [[paradox]]es, in a shorter version of the [[ParadoxesVideo]]. Stop by and get a chance to win [[TheAPIBook]]. I am not sure what will be the final quiz to win [[TheAPIBook]], but I'd suggest following one: Can you write a code that throw ''NullPointerException'' directly from the following ''Interval'' class?		[[Ostrava]] is 3rd largest town in Czech Republic. I'll be in [[wikipedia:Ostrava\|Ostrava]] at [http://java.cz/article/czjug-ostrava-brezen-2011 JUG meeting] on Mar 2nd, 2011. I'll talk about [[paradox]]es, in a shorter version of the [[ParadoxesVideo]]. Stop by and get a chance to win [[TheAPIBook]]. I am not sure what will be the final quiz to win [[TheAPIBook]], but I'd suggest following one: Can you write a code that throw ''NullPointerException'' directly from the following ''Interval'' class?

-	<source lang="java">	+	<source lang="java" snippet="interval.api"/>
-	~~/** Quiz: Anyone can come up with a JUnit test to generate~~	+
-	* {@link NullPointerException} directly from the code of	+
-	* the <code>Interval</code> class?	+
-	*/	+
-	~~public final class Interval {~~	+
-	~~private final Date from, to;~~	+
-		+
-	~~/** Constructs interval between two dates.~~	+
-	*	+
-	* @param from the 'sooner' date	+
-	* @param to the 'later' date	+
-	* @throws IllegalArgumentException if <code>from</code> is not less then <code>to</code>	+
-	*/	+
-	~~public Interval(Date from, Date to) {~~	+
-	~~if (from~~ =~~= null) {~~	+
-	~~throw new IllegalArgumentException(~~"~~'from' cannot be null!");~~	+
-	}	+
-	~~if (to == null) {~~	+
-	~~throw new IllegalArgumentException("'to' cannot be null!");~~	+
-	}	+
-	~~// shield us from Date's mutability~~	+
-	~~this~~.~~from = (Date) from.clone();~~	+
-	~~this.to = (Date)to.clone();~~	+
-	~~if (from.compareTo(to) >= 0) {~~	+
-	~~throw new IllegalArgumentException(~~"~~'from' must be lower than 'to'!");~~	+
-	}	+
-	}	+
-		+
-	~~/** The length of the interval in milliseconds~~	+
-	*	+
-	* @return amount of milliseconds between 'from' and 'to' dates.	+
-	*/	+
-	~~public long getLength() {~~	+
-	~~return to.getTime() - from.getTime();~~	+
-	}	+
-	}	+
-	</~~source~~>	+

-	I ~~followed~~ all the 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 really ~~write~~ bullet proof 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 really 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''':
		+
		+	<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.

JaroslavTulach at 10:31, 2 March 2011

2011-03-02T10:31:16Z

←Older revision		Revision as of 10:31, 2 March 2011
Line 1:		Line 1:
-	I'll be in [[wikipedia:Ostrava\|Ostrava]] at [http://java.cz/article/czjug-ostrava-brezen-2011 JUG meeting] on Mar 2nd, 2011. I'll talk about [[paradox]]es, in a shorter version of the [[ParadoxesVideo]]. Stop by and get a chance to win [[TheAPIBook]]. I am not sure what will be the final quiz to win [[TheAPIBook]], but I'd suggest following one: Can you write a code that throw ''NullPointerException'' directly from the following ''Interval'' class?	+	[[Ostrava]] is 3rd largest town in Czech Republic. I'll be in [[wikipedia:Ostrava\|Ostrava]] at [http://java.cz/article/czjug-ostrava-brezen-2011 JUG meeting] on Mar 2nd, 2011. I'll talk about [[paradox]]es, in a shorter version of the [[ParadoxesVideo]]. Stop by and get a chance to win [[TheAPIBook]]. I am not sure what will be the final quiz to win [[TheAPIBook]], but I'd suggest following one: Can you write a code that throw ''NullPointerException'' directly from the following ''Interval'' class?

	<source lang="java">		<source lang="java">

JaroslavTulach at 20:06, 1 March 2011

2011-03-01T20:06:04Z

←Older revision		Revision as of 20:06, 1 March 2011
Line 40:		Line 40:
	</source>		</source>

-	I followed all the advices of [[TheAPIBook]]. I made the class final, I check for wrong arguments. I guard myself against mutability of ''Date''. Is it really write bullet proof code?	+	I followed all the 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 really write bullet proof code?

JaroslavTulach at 20:05, 1 March 2011

2011-03-01T20:05:24Z

←Older revision		Revision as of 20:05, 1 March 2011
Line 5:		Line 5:
	* {@link NullPointerException} directly from the code of		* {@link NullPointerException} directly from the code of
	* the <code>Interval</code> class?		* the <code>Interval</code> class?
-	*
-	* @author Jaroslav Tulach <jtulach@netbeans.org>
	*/		*/
	public final class Interval {		public final class Interval {

JaroslavTulach at 20:04, 1 March 2011

2011-03-01T20:04:58Z

←Older revision		Revision as of 20:04, 1 March 2011
Line 1:		Line 1:
-	I'll be in [[wikipedia:Ostrava\|Ostrava]] at [http://java.cz/article/czjug-ostrava-brezen-2011 JUG meeting] on Mar 2nd, 2011. I'll talk about [[paradox]]es, in a shorter version of the [[ParadoxesVideo]]. Stop by and get a chance to win [[TheAPIBook]].	+	I'll be in [[wikipedia:Ostrava\|Ostrava]] at [http://java.cz/article/czjug-ostrava-brezen-2011 JUG meeting] on Mar 2nd, 2011. I'll talk about [[paradox]]es, in a shorter version of the [[ParadoxesVideo]]. Stop by and get a chance to win [[TheAPIBook]]. I am not sure what will be the final quiz to win [[TheAPIBook]], but I'd suggest following one: Can you write a code that throw ''NullPointerException'' directly from the following ''Interval'' class?
		+
		+	<source lang="java">
		+	/** Quiz: Anyone can come up with a JUnit test to generate
		+	* {@link NullPointerException} directly from the code of
		+	* the <code>Interval</code> class?
		+	*
		+	* @author Jaroslav Tulach <jtulach@netbeans.org>
		+	*/
		+	public final class Interval {
		+	private final Date from, to;
		+
		+	/** Constructs interval between two dates.
		+	*
		+	* @param from the 'sooner' date
		+	* @param to the 'later' date
		+	* @throws IllegalArgumentException if <code>from</code> is not less then <code>to</code>
		+	*/
		+	public Interval(Date from, Date to) {
		+	if (from == null) {
		+	throw new IllegalArgumentException("'from' cannot be null!");
		+	}
		+	if (to == null) {
		+	throw new IllegalArgumentException("'to' cannot be null!");
		+	}
		+	// shield us from Date's mutability
		+	this.from = (Date) from.clone();
		+	this.to = (Date)to.clone();
		+	if (from.compareTo(to) >= 0) {
		+	throw new IllegalArgumentException("'from' must be lower than 'to'!");
		+	}
		+	}
		+
		+	/** The length of the interval in milliseconds
		+	*
		+	* @return amount of milliseconds between 'from' and 'to' dates.
		+	*/
		+	public long getLength() {
		+	return to.getTime() - from.getTime();
		+	}
		+	}
		+	</source>
		+
		+	I followed all the advices of [[TheAPIBook]]. I made the class final, I check for wrong arguments. I guard myself against mutability of ''Date''. Is it really write bullet proof code?