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copied!<p>Is there something tricky that I'm not catching? There probably is... (<strong>edit:</strong> yes, there is!)</p> <pre><code>class AllInts { public static void main(String[] args) { // wrong -- i <= Integer.MAX_VALUE will never be false, since // incrementing Integer.MAX_VALUE overflows to Integer.MIN_VALUE. for (int i = Integer.MIN_VALUE; i <= Integer.MAX_VALUE; i++) { System.out.println(i); } } } </code></pre> <p>Since the printing is the bottleneck, a buffer would improve the speed quite a lot (I know because I just tried it):</p> <pre><code>class AllInts { public static void main(String[] args) { // a rather large cache; I did no calculations to optimize the cache // size, but adding the first group of numbers will make the buffer // as large as it will ever need to be. StringBuilder buffer = new StringBuilder(10000000); int counter = 0; // note that termination check is now < // this means Integer.MAX_VALUE won't be printed in the loop for (int i = Integer.MIN_VALUE; i < Integer.MAX_VALUE; i++) { buffer.append(i).append('\n'); if (++counter > 5000000) { System.out.print(buffer); buffer.delete(0, buffer.length()-1); counter = 0; } } // take care of the last value (also means we don't have to check // if the buffer is empty before printing it) buffer.append(Integer.MAX_VALUE); System.out.println(buffer); } } </code></pre> <p>Also, this version will actually terminate (thanks to Daniel Lew for pointing out that there was, in fact, something tricky that I wasn't catching).</p> <p>The total run time for this version (run with -Xmx512m) was 1:53. That's over 600000 numbers/second; not bad at all! But I suspect that it would have been slower if I hadn't run it minimized.</p>

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