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| <title>ProGuard Limitations</title> |
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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> |
| |
| <li>For efficiency, ProGuard always ignores any <b>private or package visible |
| library classes</b> while reading library jars. If any of them are |
| extended by public library classes, and then extended again by input |
| classes, ProGuard will complain it can't find them. In that case, you'll |
| have to use the <code>-dontskipnonpubliclibraryclasses</code> option, and |
| maybe even the <code>-dontskipnonpubliclibraryclassmembers</code> option. |
| The graphical user interface has checkboxes for these settings. |
| <p> |
| |
| <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. |
| <p> |
| |
| <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. |
| <p> |
| |
| <li>When obfuscating, ProGuard will write out class files named |
| "<code>a.class</code>", "<code>b.class</code>", etc. If there is a large |
| numbers of classes in the same package, it may also write out |
| <b>"<code>aux.class</code>"</b>. Windows doesn't allow creating files with |
| this reserved name (among a few other names), so it's generally better to |
| write the output to a jar, in order to avoid such problems. |
| <p> |
| |
| </ul> |
| <p> |
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| <hr> |
| <address> |
| Copyright © 2002-2009 |
| <a href="http://www.graphics.cornell.edu/~eric/">Eric Lafortune</a>. |
| </address> |
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