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POWhy does this method print 4?
 

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  1. POWhy does this method print 4?
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    <p>I was wondering what happens when you try to catch an StackOverflowError and came up with the following method:</p> <pre><code>class RandomNumberGenerator { static int cnt = 0; public static void main(String[] args) { try { main(args); } catch (StackOverflowError ignore) { System.out.println(cnt++); } } } </code></pre> <p>Now my question:</p> <p>Why does this method print '4'?</p> <p>I thought maybe it was because <code>System.out.println()</code> needs 3 segments on the call stack, but I don't know where the number 3 comes from. When you look at the source code (and bytecode) of <code>System.out.println()</code>, it normally would lead to far more method invocations than 3 (so 3 segments on the call stack would not be sufficient). If it's because of optimizations the Hotspot VM applies (method inlining), I wonder if the result would be different on another VM.</p> <p><b>Edit</b>:</p> <p>As the output seems to be highly JVM specific, I get the result 4 using<br> Java(TM) SE Runtime Environment (build 1.6.0_41-b02)<br> Java HotSpot(TM) 64-Bit Server VM (build 20.14-b01, mixed mode)</p> <p><br></p> <p><b> Explanation why I think this question is different from <a href="https://stackoverflow.com/questions/15083318/understanding-java-stack">Understanding the Java stack</a>: </b></p> <p>My question is not about why there is a cnt > 0 (obviously because <code>System.out.println()</code> requires stack size and throws another <code>StackOverflowError</code> before something gets printed), but why it has the particular value of 4, respectively 0,3,8,55 or something else on other systems.</p>
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    1. COIn my local, I am getting "0" as expected.
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    2. CO++cnt is giving "1". so the result is as expected. Bit strange from your answer.
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    3. COI have run your code and it prints '1'
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