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POI found a bug in Java Puzzlers VI - can someone explain it?
 

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  1. POI found a bug in Java Puzzlers VI - can someone explain it?
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    <p>Take a look at this <a href="http://code.google.com/edu/languages/index.html#_java_puzzlers" rel="noreferrer">java puzzles vid</a> by Josh Bloch and William Pugh, around time index 0:25:00-0:33:00.</p> <p>One of the speakers says that if you use lowercase <code>boolean</code> instead of <code>Boolean</code>, then <code>LIVING</code> will be treated as a true "compile time constant", and it no longer matters when it is initialized.</p> <p>Well, this is all fine and dandy, but, take a look at what happens when you revert to the original order between the static init and the constructor, and then follow it up by a simple "Extract Method" operation. These two programs print different outputs:</p> <pre><code>public class Elvis { private static final Elvis ELVIS = new Elvis(); private Elvis () {} private static final boolean LIVING = true; private final boolean alive = LIVING; private final boolean lives () {return alive;} public static void main(String[] args) { System.out.println(ELVIS.lives()); // prints true } } </code></pre> <p>And with the refactored <code>returnTrue()</code> method</p> <pre><code>public class Elvis { private static final Elvis ELVIS = new Elvis(); private Elvis () {} private static final boolean LIVING = returnTrue(); private static boolean returnTrue() { return true; } private final boolean alive = LIVING; private final boolean lives () {return alive;} public static void main(String[] args) { System.out.println(ELVIS.lives()); // prints false } } </code></pre> <p>Why does extracting the returnTrue() method change the program output in this case?</p>
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      1. POI found a bug in Java Puzzlers VI - can someone explain it?
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    1. COAre you saying there are bugs in a bug/video about bugs? i think its called recurrence and you can get stackoverflow(but you are already on stackoverflow) :|
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      1. POI found a bug in Java Puzzlers VI - can someone explain it?
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    2. CO+1 - I didn't know the answer. I forwarded to someone who does.
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