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| <h2>Limitations</h2> |
| |
| When using ProGuard, you should be aware of a few technical issues, all of |
| which are easily avoided or resolved: |
| <p> |
| <ul class="spacious"> |
| |
| <li>For best results, ProGuard's optimization algorithms assume that the |
| processed code never <b>intentionally throws NullPointerExceptions</b> or |
| ArrayIndexOutOfBoundsExceptions, or even OutOfMemoryErrors or |
| StackOverflowErrors, in order to achieve something useful. For instance, |
| it may remove a method call <code>myObject.myMethod()</code> if that call |
| wouldn't have any effect. It ignores the possibility that |
| <code>myObject</code> might be null, causing a NullPointerException. In |
| some way this is a good thing: optimized code may throw fewer exceptions. |
| Should this entire assumption be false, you'll have to switch off |
| optimization using the <code>-dontoptimize</code> option.</li> |
| |
| <li>ProGuard's optimization algorithms currently also assume that the |
| processed code never creates <b>busy-waiting loops</b> without at least |
| testing on a volatile field. Again, it may remove such loops. Should this |
| assumption be false, you'll have to switch off optimization using |
| the <code>-dontoptimize</code> option.</li> |
| |
| <li>If an input jar and a library jar contain classes in the <b>same |
| package</b>, the obfuscated output jar may contain class names that |
| overlap with class names in the library jar. This is most likely if the |
| library jar has been obfuscated before, as it will then probably contain |
| classes named 'a', 'b', etc. Packages should therefore never be split |
| across input jars and library jars.</li> |
| |
| <li>When obfuscating, ProGuard writes out class files named |
| "<code>a.class</code>", "<code>b.class</code>", etc. If a package contains |
| a large number of classes, ProGuard may also write out |
| <b>"<code>aux.class</code>"</b>. Inconveniently, Windows refuses to create |
| files with this reserved name (among a few other names). It's generally |
| better to write the output to a jar, in order to avoid such problems.</li> |
| |
| </ul> |
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| <a target="other" href="http://www.lafortune.eu/">Eric Lafortune</a>. |
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