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<h2>Examples</h2>

Some typical useful configurations:
<ol>
<li><a href="#application">A typical application</a></li>
<li><a href="#applet">A typical applet</a></li>
<li><a href="#midlet">A typical midlet</a></li>
<li><a href="#jcapplet">A typical Java Card applet</a></li>
<li><a href="#xlet">A typical xlet</a></li>
<li><a href="#androidactivity">A simple Android activity</a></li>
<li><a href="#androidapplication">A complete Android application</a></li>
<li><a href="#library">A typical library</a></li>
<li><a href="#applications">All possible applications in the input jars</a></li>
<li><a href="#applets">All possible applets in the input jars</a></li>
<li><a href="#midlets">All possible midlets in the input jars</a></li>
<li><a href="#jcapplets">All possible Java Card applets in the input jars</a></li>
<li><a href="#xlets">All possible xlets in the input jars</a></li>
<li><a href="#servlets">All possible servlets in the input jars</a></li>
<li><a href="#scala">Scala applications with the Scala runtime</a></li>
<li><a href="#native">Processing native methods</a></li>
<li><a href="#callback">Processing callback methods</a></li>
<li><a href="#enumerations">Processing enumeration classes</a></li>
<li><a href="#serializable">Processing serializable classes</a></li>
<li><a href="#beans">Processing bean classes</a></li>
<li><a href="#annotations">Processing annotations</a></li>
<li><a href="#database">Processing database drivers</a></li>
<li><a href="#componentui">Processing ComponentUI classes</a></li>
<li><a href="#rmi">Processing RMI code</a></li>
<li><a href="#resourcefiles">Processing resource files</a></li>
<li><a href="#manifestfiles">Processing manifest files</a></li>
<li><a href="#stacktrace">Producing useful obfuscated stack traces</a></li>
<li><a href="#repackaging">Obfuscating package names</a></li>
<li><a href="#restructuring">Restructuring the output archives</a></li>
<li><a href="#filtering">Filtering the input and the output</a></li>
<li><a href="#multiple">Processing multiple applications at once</a></li>
<li><a href="#incremental">Incremental obfuscation</a></li>
<li><a href="#microedition">Preverifying class files for Java Micro Edition</a></li>
<li><a href="#upgrade">Upgrading class files to Java 6</a></li>
<li><a href="#deadcode">Finding dead code</a></li>
<li><a href="#structure">Printing out the internal structure of class files</a></li>
<li><a href="#annotated">Using annotations to configure ProGuard</a></li>
</ol>

You can find some sample configuration files in the <code>examples</code>
directory of the ProGuard distribution.

<h3><a name="application">A typical application</a></h3>

To shrink, optimize, and obfuscate a simple Java application, you typically
create a configuration file like <code>myconfig.pro</code>, which can be used
with
<pre>
bin/proguard @myconfig.pro
</pre>
<p>
The configuration file specifies the input, the output, and the entry points
of the application:
<pre>
-injars       myapplication.jar
-outjars      myapplication_out.jar
-libraryjars  &lt;java.home&gt;/lib/rt.jar
-printmapping myapplication.map

-keep public class mypackage.MyMain {
    public static void main(java.lang.String[]);
}
</pre>
<p>
Note the use of the <code>&lt;java.home&gt;</code> system property. ProGuard
automatically replaces it when parsing the file.
<p>
The <a href="usage.html#keep"><code>-keep</code></a> option specifies the
entry point of the application that has to be preserved.
The access modifiers <code>public</code> and <code>static</code> are not
really required in this case, since we know a priori that the specified class
and method have the proper access flags. It just looks more familiar this way.
<p>
Note that all type names are fully specified:
<code>mypackage.MyMain</code> and <code>java.lang.String[]</code>.
<p>
We're writing out an obfuscation mapping file with <a
href="usage.html#printmapping"><code>-printmapping</code></a>, for
de-obfuscating any stack traces later on, or for incremental obfuscation of
extensions.
<p>
We can further improve the results with a few additional options:
<pre>
-optimizationpasses 3
-overloadaggressively
-repackageclasses ''
-allowaccessmodification
</pre>
These options are not required; they just shave off some extra bytes from the
output jar, by performing up to 3 optimization passes, and by aggressively
obfuscating class members and <a href="#repackaging">package names</a>.
<p>
In general, you might need a few additional options for processing <a
href="#native">native methods</a>, <a href="#callback">callback methods</a>,
<a href="#enumerations">enumerations</a>, <a href="#serializable">serializable
classes</a>, <a href="#beans">bean classes</a>, <a
href="#annotations">annotations</a>, and <a href="#resourcefiles">resource
files</a>.

<h3><a name="applet">A typical applet</a></h3>

These options shrink, optimize, and obfuscate the applet
<code>mypackage.MyApplet</code>:
<pre>
-injars      in.jar
-outjars     out.jar
-libraryjars &lt;java.home&gt;/lib/rt.jar

-keep public class mypackage.MyApplet
</pre>
<p>
The typical applet methods will be preserved automatically, since
<code>mypackage.MyApplet</code> is an extension of the <code>Applet</code>
class in the library <code>rt.jar</code>.
<p>
If applicable, you should add options for processing <a href="#native">native
methods</a>, <a href="#callback">callback methods</a>, <a
href="#enumerations">enumerations</a>, <a href="#serializable">serializable
classes</a>, <a href="#beans">bean classes</a>, <a
href="#annotations">annotations</a>, and <a href="#resourcefiles">resource
files</a>.

<h3><a name="midlet">A typical midlet</a></h3>

These options shrink, optimize, obfuscate, and preverify the midlet
<code>mypackage.MyMIDlet</code>:
<pre>
-injars      in.jar
-outjars     out.jar
-libraryjars /usr/local/java/wtk2.5.2/lib/midpapi20.jar
-libraryjars /usr/local/java/wtk2.5.2/lib/cldcapi11.jar
-overloadaggressively
-repackageclasses ''
-allowaccessmodification
-microedition

-keep public class mypackage.MyMIDlet
</pre>
<p>
Note how we're now targeting the Java Micro Edition run-time environment of
<code>midpapi20.jar</code> and <code>cldcapi11.jar</code>, instead of the Java
Standard Edition run-time environment <code>rt.jar</code>. You can target
other JME environments by picking the appropriate jars.
<p>
The typical midlet methods will be preserved automatically, since
<code>mypackage.MyMIDlet</code> is an extension of the <code>MIDlet</code>
class in the library <code>midpapi20.jar</code>.
<p>
The <a href="usage.html#microedition"><code>-microedition</code></a> option
makes sure the class files are preverified for Java Micro Edition, producing
compact <code>StackMap</code> attributes. It is no longer necessary to run an
external preverifier.
<p>
Be careful if you do use the external <code>preverify</code> tool on a platform
with a case-insensitive filing system, such as Windows. Because this tool
unpacks your processed jars, you should then use ProGuard's <a
href="usage.html#dontusemixedcaseclassnames"><code>-dontusemixedcaseclassnames</code></a>
option.
<p>
If applicable, you should add options for processing <a href="#native">native
methods</a> and <a href="#resourcefiles">resource files</a>.
<p>
Note that you will still have to adapt the midlet jar size in the
corresponding jad file; ProGuard doesn't do that for you.

<h3><a name="jcapplet">A typical Java Card applet</a></h3>

These options shrink, optimize, and obfuscate the Java Card applet
<code>mypackage.MyApplet</code>:
<pre>
-injars      in.jar
-outjars     out.jar
-libraryjars /usr/local/java/javacard2.2.2/lib/api.jar
-dontwarn    java.lang.Class
-overloadaggressively
-repackageclasses ''
-allowaccessmodification

-keep public class mypackage.MyApplet
</pre>
<p>
The configuration is very similar to the configuration for midlets, except that
it now targets the Java Card run-time environment. This environment doesn't
have java.lang.Class, so we're telling ProGuard not to worry about it.

<h3><a name="xlet">A typical xlet</a></h3>

These options shrink, optimize, and obfuscate the xlet
<code>mypackage.MyXlet</code>:
<pre>
-injars      in.jar
-outjars     out.jar
-libraryjars /usr/local/java/jtv1.1/javatv.jar
-libraryjars /usr/local/java/cdc1.1/lib/cdc.jar
-libraryjars /usr/local/java/cdc1.1/lib/btclasses.zip
-overloadaggressively
-repackageclasses ''
-allowaccessmodification

-keep public class mypackage.MyXlet
</pre>
<p>
The configuration is very similar to the configuration for midlets, except that
it now targets the CDC run-time environment with the Java TV API.

<h3><a name="androidactivity">A simple Android activity</a></h3>

These options shrink, optimize, and obfuscate the single Android
activity <code>mypackage.MyActivity</code>:
<pre>
-injars      bin/classes
-outjars     bin/classes-processed.jar
-libraryjars /usr/local/java/android-sdk/platforms/android-9/android.jar

-dontpreverify
-repackageclasses ''
-allowaccessmodification
-optimizations !code/simplification/arithmetic

-keep public class mypackage.MyActivity
</pre>
<p>
We're targeting the Android run-time and keeping the activity as an entry
point.
<p>
Preverification is irrelevant for the dex compiler and the Dalvik VM, so we
can switch it off with the
<a href="usage.html#dontpreverify"><code>-dontpreverify</code></a> option.
<p>
The <a href="usage.html#optimizations"><code>-optimizations</code></a> option
disables some arithmetic simplifications that Dalvik 1.0 and 1.5 can't handle.
Note that the Dalvik VM also can't
handle <a href="usage.html#overloadaggressively">aggressive overloading</a>
(of static fields).
<p>
If applicable, you should add options for processing <a href="#native">native
methods</a>, <a href="#callback">callback methods</a>,
<a href="#enumerations">enumerations</a>,
<a href="#annotations">annotations</a>, and
<a href="#resourcefiles">resource files</a>.

<h3><a name="androidapplication">A complete Android application</a></h3>

These options shrink, optimize, and obfuscate all public activities, services,
broadcast receivers, and content providers from the compiled classes and
external libraries:
<pre>
-injars      bin/classes
-injars      libs
-outjars     bin/classes-processed.jar
-libraryjars /usr/local/java/android-sdk/platforms/android-9/android.jar

-dontpreverify
-repackageclasses ''
-allowaccessmodification
-optimizations !code/simplification/arithmetic
-keepattributes *Annotation*

-keep public class * extends android.app.Activity
-keep public class * extends android.app.Application
-keep public class * extends android.app.Service
-keep public class * extends android.content.BroadcastReceiver
-keep public class * extends android.content.ContentProvider

-keep public class * extends android.view.View {
    public &lt;init&gt;(android.content.Context);
    public &lt;init&gt;(android.content.Context, android.util.AttributeSet);
    public &lt;init&gt;(android.content.Context, android.util.AttributeSet, int);
    public void set*(...);
}

-keepclasseswithmembers class * {
    public &lt;init&gt;(android.content.Context, android.util.AttributeSet);
}

-keepclasseswithmembers class * {
    public &lt;init&gt;(android.content.Context, android.util.AttributeSet, int);
}

-keepclassmembers class * implements android.os.Parcelable {
    static android.os.Parcelable$Creator CREATOR;
}

-keepclassmembers class **.R$* {
    public static &lt;fields&gt;;
}
</pre>
<p>
Most importantly, we're keeping all fundamental classes that may be referenced
by the <code>AndroidManifest.xml</code> file of the application. If your
manifest file contains other classes and methods, you may have to specify
those as well.
<p>
We're keeping annotations, since they might be used by custom
<code>RemoteViews</code>.
<p>
We're keeping any custom <code>View</code> extensions and other classes with
typical constructors, since they might be referenced from XML layout files.
<p>
We're also keeping the required static fields in <code>Parcelable</code>
implementations, since they are accessed by introspection.
<p>
Finally, we're keeping the static fields of referenced inner classes of
auto-generated <code>R</code> classes, just in case your code is accessing
those fields by introspection. Note that the compiler already inlines
primitive fields, so ProGuard can generally remove all these classes entirely
anyway (because the classes are not referenced and therefore not required).
<p>
If you're using additional Google APIs, you'll have to specify
those as well, for instance:
<pre>
-libraryjars /usr/local/android-sdk/add-ons/google_apis-7_r01/libs/maps.jar
</pre>
<p>
If you're using Google's optional License Verification Library, you can
obfuscate its code along with your own code. You do have to preserve
its <code>ILicensingService</code> interface for the library to work:
<pre>
-keep public interface com.android.vending.licensing.ILicensingService
</pre>
<p>
If you're using the Android Compatibility library, you should add the
following line, to let ProGuard know it's ok that the library references some
classes that are not available in all versions of the API:
<pre>
-dontwarn android.support.**
</pre>
<p>
If applicable, you should add options for processing <a href="#native">native
methods</a>, <a href="#callback">callback methods</a>,
<a href="#enumerations">enumerations</a>,
and <a href="#resourcefiles">resource files</a>. You may also want to add
options for producing <a href="#stacktrace">useful stack traces</a>. You can
find a complete sample configuration in <code>examples/android.pro</code> in
the ProGuard distribution.
<p>
The build process of the Android SDK (version 2.3 and higher) already
integrates ProGuard by default. You only need to enable it (for release
builds) by adding <code>proguard.config=proguard.cfg</code> to the file
<code>build.properties</code>. In case of problems, you may want to check if
the automatically generated file <code>proguard.cfg</code> contains the
settings discussed above. The generated Ant build file already sets the input
and output files for you.
<p>
For more information, you can consult the official <a target="other"
href="http://developer.android.com/guide/developing/tools/proguard.html">Developer
Guide</a> in the Android SDK.

<h3><a name="library">A typical library</a></h3>

These options shrink, optimize, and obfuscate an entire library, keeping all
public and protected classes and class members, native method names, and
serialization code. The processed version of the library can then still be
used as such, for developing code based on its public API.
<pre>
-injars       in.jar
-outjars      out.jar
-libraryjars  &lt;java.home&gt;/lib/rt.jar
-printmapping out.map

-keepparameternames
-renamesourcefileattribute SourceFile
-keepattributes Exceptions,InnerClasses,Signature,Deprecated,
                SourceFile,LineNumberTable,*Annotation*,EnclosingMethod

-keep public class * {
    public protected *;
}

-keepclassmembernames class * {
    java.lang.Class class$(java.lang.String);
    java.lang.Class class$(java.lang.String, boolean);
}

-keepclasseswithmembernames class * {
    native &lt;methods&gt;;
}

-keepclassmembers enum * {
    public static **[] values();
    public static ** valueOf(java.lang.String);
}

-keepclassmembers class * implements java.io.Serializable {
    static final long serialVersionUID;
    private static final java.io.ObjectStreamField[] serialPersistentFields;
    private void writeObject(java.io.ObjectOutputStream);
    private void readObject(java.io.ObjectInputStream);
    java.lang.Object writeReplace();
    java.lang.Object readResolve();
}
</pre>
<p>
This configuration should preserve everything we'll ever want to access in the
library. Only if there are any other non-public classes or methods that are
invoked dynamically, they should be specified using additional <a
href="usage.html#keep"><code>-keep</code></a> options.
<p>
The <a
href="usage.html#keepclassmembernames"><code>-keepclassmembernames</code></a>
option for the <code>class$</code> methods is not strictly necessary. These
methods are inserted by the <code>javac</code> compiler and the
<code>jikes</code> compiler respectively, in JDK 1.2 and older, to implement
the <code>.class</code> construct. ProGuard will automatically detect them and
deal with them, even when their names have been obfuscated. However, other
obfuscators may rely on the original method names. It may therefore be helpful
to preserve them, in case these other obfuscators are ever used for further
obfuscation of the library.
<p>
The "Exceptions" attribute has to be preserved, so the compiler knows which
exceptions methods may throw.
<p>
The "InnerClasses" attribute (or more precisely, its source name part) has to
be preserved too, for any inner classes that can be referenced from outside the
library. The <code>javac</code> compiler would be unable to find the inner
classes otherwise.
<p>
The "Signature" attribute is required to be able to access generic types when
compiling in JDK 5.0 and higher.
<p>
The <a href="usage.html#keepparameternames"><code>-keepparameternames</code></a>
option keeps the parameter names in the "LocalVariableTable" and
"LocalVariableTypeTable" attributes of public library methods. Some IDEs can
present these names to the developers who use the library.
<p>
Finally, we're keeping the "Deprecated" attribute and the attributes for
producing <a href="#stacktrace">useful stack traces</a>.
<p>
We've also added some options for for processing <a href="#native">native
methods</a>, <a href="#enumerations">enumerations</a>, <a
href="#serializable">serializable classes</a>, and <a
href="#annotations">annotations</a>, which are all discussed in their
respective examples.

<h3><a name="applications">All possible applications in the input jars</a></h3>

These options shrink, optimize, and obfuscate all public applications in
<code>in.jar</code>:
<pre>
-injars      in.jar
-outjars     out.jar
-libraryjars &lt;java.home&gt;/lib/rt.jar
-printseeds

-keepclasseswithmembers public class * {
    public static void main(java.lang.String[]);
}
</pre>
<p>
Note the use of <a
href="usage.html#keepclasseswithmembers"><code>-keepclasseswithmembers</code></a>.
We don't want to preserve all classes, just all classes that have main
methods, and those methods.
<p>
The <a href="usage.html#printseeds"><code>-printseeds</code></a> option prints
out which classes exactly will be preserved, so we know for sure we're getting
what we want.
<p>
If applicable, you should add options for processing <a href="#native">native
methods</a>, <a href="#callback">callback methods</a>, <a
href="#enumerations">enumerations</a>, <a href="#serializable">serializable
classes</a>, <a href="#beans">bean classes</a>, <a
href="#annotations">annotations</a>, and <a href="#resourcefiles">resource
files</a>.

<h3><a name="applets">All possible applets in the input jars</a></h3>

These options shrink, optimize, and obfuscate all public applets in
<code>in.jar</code>:
<pre>
-injars      in.jar
-outjars     out.jar
-libraryjars &lt;java.home&gt;/lib/rt.jar
-printseeds

-keep public class * extends java.applet.Applet
</pre>
<p>
We're simply keeping all classes that extend the <code>Applet</code> class.
<p>
Again, the <a href="usage.html#printseeds"><code>-printseeds</code></a> option
prints out which applets exactly will be preserved.
<p>
If applicable, you should add options for processing <a href="#native">native
methods</a>, <a href="#callback">callback methods</a>, <a
href="#enumerations">enumerations</a>, <a href="#serializable">serializable
classes</a>, <a href="#beans">bean classes</a>, <a
href="#annotations">annotations</a>, and <a href="#resourcefiles">resource
files</a>.

<h3><a name="midlets">All possible midlets in the input jars</a></h3>

These options shrink, optimize, obfuscate, and preverify all public midlets in
<code>in.jar</code>:
<pre>
-injars      in.jar
-outjars     out.jar
-libraryjars /usr/local/java/wtk2.5.2/lib/midpapi20.jar
-libraryjars /usr/local/java/wtk2.5.2/lib/cldcapi11.jar
-overloadaggressively
-repackageclasses ''
-allowaccessmodification
-microedition
-printseeds

-keep public class * extends javax.microedition.midlet.MIDlet
</pre>
<p>
We're simply keeping all classes that extend the <code>MIDlet</code> class.
<p>
The <a href="usage.html#microedition"><code>-microedition</code></a> option
makes sure the class files are preverified for Java Micro Edition, producing
compact <code>StackMap</code> attributes. It is no longer necessary to run an
external preverifier.
<p>
Be careful if you do use the external <code>preverify</code> tool on a platform
with a case-insensitive filing system, such as Windows. Because this tool
unpacks your processed jars, you should then use ProGuard's <a
href="usage.html#dontusemixedcaseclassnames"><code>-dontusemixedcaseclassnames</code></a>
option.
<p>
The <a href="usage.html#printseeds"><code>-printseeds</code></a> option prints
out which midlets exactly will be preserved.
<p>
If applicable, you should add options for processing <a href="#native">native
methods</a> and <a href="#resourcefiles">resource files</a>.
<p>
Note that you will still have to adapt the midlet jar size in the
corresponding jad file; ProGuard doesn't do that for you.

<h3><a name="jcapplets">All possible Java Card applets in the input jars</a></h3>

These options shrink, optimize, and obfuscate all public Java Card applets in
<code>in.jar</code>:
<pre>
-injars      in.jar
-outjars     out.jar
-libraryjars /usr/local/java/javacard2.2.2/lib/api.jar
-dontwarn    java.lang.Class
-overloadaggressively
-repackageclasses ''
-allowaccessmodification
-printseeds

-keep public class * implements javacard.framework.Applet
</pre>
<p>
We're simply keeping all classes that implement the <code>Applet</code>
interface.
<p>
The <a href="usage.html#printseeds"><code>-printseeds</code></a> option prints
out which applets exactly will be preserved.

<h3><a name="xlets">All possible xlets in the input jars</a></h3>

These options shrink, optimize, and obfuscate all public xlets in
<code>in.jar</code>:
<pre>
-injars      in.jar
-outjars     out.jar
-libraryjars /usr/local/java/jtv1.1/javatv.jar
-libraryjars /usr/local/java/cdc1.1/lib/cdc.jar
-libraryjars /usr/local/java/cdc1.1/lib/btclasses.zip
-overloadaggressively
-repackageclasses ''
-allowaccessmodification
-printseeds

-keep public class * implements javax.tv.xlet.Xlet
</pre>
<p>
We're simply keeping all classes that implement the <code>Xlet</code> interface.
<p>
The <a href="usage.html#printseeds"><code>-printseeds</code></a> option prints
out which xlets exactly will be preserved.

<h3><a name="servlets">All possible servlets in the input jars</a></h3>

These options shrink, optimize, and obfuscate all public servlets in
<code>in.jar</code>:
<pre>
-injars      in.jar
-outjars     out.jar
-libraryjars &lt;java.home&gt;/lib/rt.jar
-libraryjars /usr/local/java/servlet/servlet.jar
-printseeds

-keep public class * implements javax.servlet.Servlet
</pre>
<p>
Keeping all servlets is very similar to keeping all applets. The servlet API
is not part of the standard run-time jar, so we're specifying it as a library.
Don't forget to use the right path name.
<p>
We're then keeping all classes that implement the <code>Servlet</code>
interface. We're using the <code>implements</code> keyword because it looks
more familiar in this context, but it is equivalent to <code>extends</code>,
as far as ProGuard is concerned.
<p>
The <a href="usage.html#printseeds"><code>-printseeds</code></a> option prints
out which servlets exactly will be preserved.
<p>
If applicable, you should add options for processing <a href="#native">native
methods</a>, <a href="#callback">callback methods</a>, <a
href="#enumerations">enumerations</a>, <a href="#serializable">serializable
classes</a>, <a href="#beans">bean classes</a>, <a
href="#annotations">annotations</a>, and <a href="#resourcefiles">resource
files</a>.

<h3><a name="scala">Scala applications with the Scala runtime</a></h3>

These options shrink, optimize, and obfuscate all public Scala applications in
<code>in.jar</code>:
<pre>
-injars      in.jar
-injars      /usr/local/java/scala-2.9.1/lib/scala-library.jar
-outjars     out.jar
-libraryjars &lt;java.home&gt;/lib/rt.jar

-dontwarn scala.**

-keepclasseswithmembers public class * {
    public static void main(java.lang.String[]);
}

-keep class * implements org.xml.sax.EntityResolver

-keepclassmembers class * {
    ** MODULE$;
}

-keepclassmembernames class scala.concurrent.forkjoin.ForkJoinPool {
    long eventCount;
    int  workerCounts;
    int  runControl;
    scala.concurrent.forkjoin.ForkJoinPool$WaitQueueNode syncStack;
    scala.concurrent.forkjoin.ForkJoinPool$WaitQueueNode spareStack;
}

-keepclassmembernames class scala.concurrent.forkjoin.ForkJoinWorkerThread {
    int base;
    int sp;
    int runState;
}

-keepclassmembernames class scala.concurrent.forkjoin.ForkJoinTask {
    int status;
}

-keepclassmembernames class scala.concurrent.forkjoin.LinkedTransferQueue {
    scala.concurrent.forkjoin.LinkedTransferQueue$PaddedAtomicReference head;
    scala.concurrent.forkjoin.LinkedTransferQueue$PaddedAtomicReference tail;
    scala.concurrent.forkjoin.LinkedTransferQueue$PaddedAtomicReference cleanMe;
}
</pre>
<p>
The configuration is essentially the same as
for <a href="#applications">processing applications</a>, because Scala is
compiled to ordinary Java bytecode. However, the example processes the Scala
runtime library as well. The processed jar can be an order of magnitude
smaller and a few times faster than the original code (for the Scala code
examples, for instance).
<p>
The <a href="usage.html#dontwarn"><code>-dontwarn</code></a> option tells
ProGuard not to complain about some artefacts in the Scala runtime, the way it
is compiled by the <code>scalac</code> compiler (at least in Scala 2.9.1 and
older). Note that this option should always be used with care.
<p>
The additional <a href="usage.html#keepoverview"><code>-keep</code></a>
options make sure that some classes and some fields that are accessed by means
of introspection are not removed or renamed.
<p>
If applicable, you should add options for processing <a href="#native">native
methods</a>, <a href="#callback">callback methods</a>, <a
href="#enumerations">enumerations</a>, <a href="#serializable">serializable
classes</a>, <a href="#beans">bean classes</a>, <a
href="#annotations">annotations</a>, and <a href="#resourcefiles">resource
files</a>.
<h3><a name="native">Processing native methods</a></h3>

If your application, applet, servlet, library, etc., contains native methods,
you'll want to preserve their names and their classes' names, so they can
still be linked to the native library. The following additional option will
ensure that:
<pre>
-keepclasseswithmembernames class * {
    native &lt;methods&gt;;
}
</pre>
<p>
Note the use of <a
href="usage.html#keepclasseswithmembernames"><code>-keepclasseswithmembernames</code></a>.
We don't want to preserve all classes or all native methods; we just want to
keep the relevant names from being obfuscated.
<p>
ProGuard doesn't look at your native code, so it won't automatically preserve
the classes or class members that are invoked by the native code. These are
entry points, which you'll have to specify explicitly.  <a
href="callback">Callback methods</a> are discussed below as a typical example.

<h3><a name="callback">Processing callback methods</a></h3>

If your application, applet, servlet, library, etc., contains callback
methods, which are called from external code (native code, scripts,...),
you'll want to preserve them, and probably their classes too. They are just
entry points to your code, much like, say, the main method of an application.
If they aren't preserved by other <code>-keep</code> options, something like
the following option will keep the callback class and method:
<pre>
-keep class mypackage.MyCallbackClass {
    void myCallbackMethod(java.lang.String);
}
</pre>
<p>
This will preserve the given class and method from being removed or renamed.

<h3><a name="enumerations">Processing enumeration classes</a></h3>

If your application, applet, servlet, library, etc., contains enumeration
classes, you'll have to preserve some special methods. Enumerations were
introduced in Java 5. The java compiler translates enumerations into classes
with a special structure. Notably, the classes contain implementations of some
static methods that the run-time environment accesses by introspection (Isn't
that just grand? Introspection is the self-modifying code of a new
generation). You have to specify these explicitly, to make sure they aren't
removed or obfuscated:
<pre>
-keepclassmembers enum * {
    public static **[] values();
    public static ** valueOf(java.lang.String);
}
</pre>

<h3><a name="serializable">Processing serializable classes</a></h3>

More complex applications, applets, servlets, libraries, etc., may contain
classes that are serialized. Depending on the way in which they are used, they
may require special attention:
<ul>

<li>Often, serialization is simply a means of transporting data, without
    long-term storage. Classes that are shrunk and obfuscated should then
    continue to function fine with the following additional options:

<pre>
-keepclassmembers class * implements java.io.Serializable {
    private static final java.io.ObjectStreamField[] serialPersistentFields;
    private void writeObject(java.io.ObjectOutputStream);
    private void readObject(java.io.ObjectInputStream);
    java.lang.Object writeReplace();
    java.lang.Object readResolve();
}
</pre>
<p>

    The <a
    href="usage.html#keepclassmembers"><code>-keepclassmembers</code></a>
    option makes sure that any serialization methods are kept. By using this
    option instead of the basic <code>-keep</code> option, we're not
    forcing preservation of <i>all</i> serializable classes, just preservation
    of the listed members of classes that are actually used.</li>

<li>Sometimes, the serialized data are stored, and read back later into newer
    versions of the serializable classes. One then has to take care the classes
    remain compatible with their unprocessed versions and with future
    processed versions. In such cases, the relevant classes will most likely
    have <code>serialVersionUID</code> fields. The following options should
    then be sufficient to ensure compatibility over time:

<pre>
-keepnames class * implements java.io.Serializable

-keepclassmembers class * implements java.io.Serializable {
    static final long serialVersionUID;
    private static final java.io.ObjectStreamField[] serialPersistentFields;
    !static !transient &lt;fields&gt;;
    private void writeObject(java.io.ObjectOutputStream);
    private void readObject(java.io.ObjectInputStream);
    java.lang.Object writeReplace();
    java.lang.Object readResolve();
}
</pre>
<p>

    The <code>serialVersionUID</code> and <code>serialPersistentFields</code>
    lines makes sure those fields are preserved, if they are present.
    The <code>&lt;fields&gt;</code> line preserves all non-static,
    non-transient fields, with their original names. The introspection of the
    serialization process and the de-serialization process will then find
    consistent names.</li>

<li>Occasionally, the serialized data have to remain compatible, but the
    classes involved lack <code>serialVersionUID</code> fields. I imagine the
    original code will then be hard to maintain, since the serial version UID
    is then computed from a list of features the serializable class. Changing
    the class ever so slightly may change the computed serial version UID. The
    list of features is specified in the section on <a
    href="http://java.sun.com/javase/6/docs/platform/serialization/spec/class.html#4100">Stream
    Unique Identifiers</a> of Sun's <a
    href="http://java.sun.com/javase/6/docs/platform/serialization/spec/serialTOC.html">Java
    Object Serialization Specification</a>. The following directives should at
    least partially ensure compatibility with the original classes:

<pre>
-keepnames class * implements java.io.Serializable

-keepclassmembers class * implements java.io.Serializable {
    static final long serialVersionUID;
    private static final java.io.ObjectStreamField[] serialPersistentFields;
    !static !transient &lt;fields&gt;;
    !private &lt;fields&gt;;
    !private &lt;methods&gt;;
    private void writeObject(java.io.ObjectOutputStream);
    private void readObject(java.io.ObjectInputStream);
    java.lang.Object writeReplace();
    java.lang.Object readResolve();
}
</pre>
<p>

    The new options force preservation of the elements involved in the UID
    computation. In addition, the user will have to manually specify all
    interfaces of the serializable classes (using something like "<code>-keep
    interface MyInterface</code>"), since these names are also used when
    computing the UID. A fast but sub-optimal alternative would be simply
    keeping all interfaces with "<code>-keep interface *</code>".</li>

</ul>
<p>

Note that the above options may preserve more classes and class members
than strictly necessary. For instance, a large number of classes may implement
the <code>Serialization</code> interface, yet only a small number may actually
ever be serialized. Knowing your application and tuning the configuration
often produces more compact results.

<h3><a name="beans">Processing bean classes</a></h3>

If your application, applet, servlet, library, etc., makes extensive use of
introspection on bean classes to find bean editor classes, or getter and
setter methods, then configuration may become painful. There's not much else
you can do than making sure the bean class names, or the getter and setter
names don't change. For instance:
<pre>
-keep public class mypackage.MyBean {
    public void setMyProperty(int);
    public int getMyProperty();
}

-keep public class mypackage.MyBeanEditor
</pre>
<p>
If there are too many elements to list explicitly, wildcards in class names
and method signatures might be helpful. This example should encompasses all
possible setters and getters in classes in the package <code>mybeans</code>:
<pre>
-keep class mybeans.** {
    void set*(***);
    void set*(int, ***);

    boolean is*();
    boolean is*(int);

    *** get*();
    *** get*(int);
}
</pre>
<p>
The '<code>***</code>' wildcard matches any type (primitive or non-primitive,
array or non-array). The methods with the '<code>int</code>' arguments matches
properties that are lists.

<h3><a name="annotations">Processing annotations</a></h3>

If your application, applet, servlet, library, etc., uses annotations, you may
want to preserve them in the processed output. Annotations are represented by
attributes that have no direct effect on the execution of the code. However,
their values can be retrieved through introspection, allowing developers to
adapt the execution behavior accordingly. By default, ProGuard treats
annotation attributes as optional, and removes them in the obfuscation step.
If they are required, you'll have to specify this explicitly:
<pre>
-keepattributes *Annotation*
</pre>
<p>
For brevity, we're specifying a wildcarded attribute name, which will match
<code>RuntimeVisibleAnnotations</code>,
<code>RuntimeInvisibleAnnotations</code>,
<code>RuntimeVisibleParameterAnnotations</code>,
<code>RuntimeInvisibleParameterAnnotations</code>, and
<code>AnnotationDefault</code>. Depending on the purpose of the processed
code, you could refine this selection, for instance not keeping the run-time
invisible annotations (which are only used at compile-time).
<p>
Some code may make further use of introspection to figure out the enclosing
methods of anonymous inner classes. In that case, the corresponding attribute
has to be preserved as well:
<pre>
-keepattributes EnclosingMethod
</pre>

<h3><a name="database">Processing database drivers</a></h3>

Database drivers are implementations of the <code>Driver</code> interface.
Since they are often created dynamically, you may want to preserve any
implementations that you are processing as entry points:
<pre>
-keep class * implements java.sql.Driver
</pre>
<p>
This option also gets rid of the note that ProGuard prints out about
<code>(java.sql.Driver)Class.forName</code> constructs, if you are
instantiating a driver in your code (without necessarily implementing any
drivers yourself).

<h3><a name="componentui">Processing ComponentUI classes</a></h3>

Swing UI look and feels are implemented as extensions of the
<code>ComponentUI</code> class. For some reason, these have to contain a
static method <code>createUI</code>, which the Swing API invokes using
introspection. You should therefore always preserve the method as an entry
point, for instance like this:
<pre>
-keep class * extends javax.swing.plaf.ComponentUI {
    public static javax.swing.plaf.ComponentUI createUI(javax.swing.JComponent);
}
</pre>
<p>
This option also keeps the classes themselves.

<h3><a name="rmi">Processing RMI code</a></h3>

Reportedly, the easiest way to handle RMI code is to process the code with
ProGuard first and then invoke the <code>rmic</code> tool. If that is not
possible, you may want to try something like this:
<pre>
-keepattributes Exceptions

-keep interface * extends java.rmi.Remote {
    &lt;methods&gt;;
}

-keep class * implements java.rmi.Remote {
    &lt;init&gt;(java.rmi.activation.ActivationID, java.rmi.MarshalledObject);
}
</pre>
<p>
The first <code>-keep</code> option keeps all your Remote interfaces and their
methods. The second one keeps all the implementations, along with their
particular RMI constructors, if any.
<p>
The <code>Exceptions</code> attribute has to be kept too, because the RMI
handling code performs introspection to check whether the method signatures
are compatible.

<h3><a name="resourcefiles">Processing resource files</a></h3>

If your application, applet, servlet, library, etc., contains resource files,
it may be necessary to adapt their names and/or their contents when the
application is obfuscated. The following two options can achieve this
automatically:
<pre>
-adaptresourcefilenames    **.properties,**.gif,**.jpg
-adaptresourcefilecontents **.properties,META-INF/MANIFEST.MF
</pre>
<p>
The <a href="usage.html#adaptresourcefilenames">-adaptresourcefilenames</a>
option in this case renames properties files and image files in the processed
output, based on the obfuscated names of their corresponding class files (if
any). The <a
href="usage.html#adaptresourcefilecontents">-adaptresourcefilecontents</a>
option looks for class names in properties files and in the manifest file, and
replaces these names by the obfuscated names (if any). You'll probably want to
adapt the filters to suit your application.

<h3><a name="manifestfiles">Processing manifest files</a></h3>

As illustrated in the previous section, manifest files can be treated like
ordinary resource files. ProGuard can adapt obfuscated class names in the
files, but it won't make any other changes. If you want anything else, you
should apply an external tool. For instance, if a manifest file contains
signing information, you should sign the jar again after it has been
processed.
<p>
If you're merging several input jars into a single output jar, you'll have to
pick one, typically by specifying <a href="usage.html#filters">filters</a>:
<pre>
-injars  in1.jar
-injars  in2.jar(!META-INF/MANIFEST.MF)
-injars  in3.jar(!META-INF/MANIFEST.MF)
-outjars out.jar
</pre>
<p>
The filters will let ProGuard copy the manifest file from the first jar and
ignore any manifest files in the second and third input jars. Note that
ProGuard will leave the order of the files in the jars unchanged; manifest
files are not necessarily put first.

<h3><a name="stacktrace">Producing useful obfuscated stack traces</a></h3>

These options let obfuscated applications or libraries produce stack traces
that can still be deciphered later on:
<pre>
-printmapping out.map

-renamesourcefileattribute SourceFile
-keepattributes SourceFile,LineNumberTable
</pre>
<p>
We're keeping all source file attributes, but we're replacing their values by
the string "SourceFile". We could use any string. This string is already
present in all class files, so it doesn't take up any extra space. If you're
working with J++, you'll want to keep the "SourceDir" attribute as well.
<p>
We're also keeping the line number tables of all methods.
<p>
Whenever both of these attributes are present, the Java run-time environment
will include line number information when printing out exception stack traces.
<p>
The information will only be useful if we can map the obfuscated names back to
their original names, so we're saving the mapping to a file
<code>out.map</code>. The information can then be used by the <a
href="retrace/index.html">ReTrace</a> tool to restore the original stack trace.

<h3><a name="repackaging">Obfuscating package names</a></h3>

Package names can be obfuscated in various ways, with increasing levels of
obfuscation and compactness. For example, consider the following classes:
<pre>
mycompany.myapplication.MyMain
mycompany.myapplication.Foo
mycompany.myapplication.Bar
mycompany.myapplication.extra.FirstExtra
mycompany.myapplication.extra.SecondExtra
mycompany.util.FirstUtil
mycompany.util.SecondUtil
</pre>
<p>
Let's assume the class name <code>mycompany.myapplication.MyMain</code> is the
main application class that is kept by the configuration. All other class names
can be obfuscated.
<p>
By default, packages that contain classes that can't be renamed aren't renamed
either, and the package hierarchy is preserved. This results in obfuscated
class names like these:
<pre>
mycompany.myapplication.MyMain
mycompany.myapplication.a
mycompany.myapplication.b
mycompany.myapplication.a.a
mycompany.myapplication.a.b
mycompany.a.a
mycompany.a.b
</pre>
<p>
The <a
href="usage.html#flattenpackagehierarchy"><code>-flattenpackagehierarchy</code></a>
option obfuscates the package names further, by flattening the package
hierarchy of obfuscated packages:
<pre>
-flattenpackagehierarchy 'myobfuscated'
</pre>
<p>
The obfuscated class names then look as follows:
<pre>
mycompany.myapplication.MyMain
mycompany.myapplication.a
mycompany.myapplication.b
myobfuscated.a.a
myobfuscated.a.b
myobfuscated.b.a
myobfuscated.b.b
</pre>
<p>
Alternatively, the <a
href="usage.html#repackageclasses"><code>-repackageclasses</code></a> option
obfuscates the entire packaging, by combining obfuscated classes into a single
package:
<pre>
-repackageclasses 'myobfuscated'
</pre>
The obfuscated class names then look as follows:
<pre>
mycompany.myapplication.MyMain
mycompany.myapplication.a
mycompany.myapplication.b
myobfuscated.a
myobfuscated.b
myobfuscated.c
myobfuscated.d
</pre>
<p>
Additionally specifying the <a
href="usage.html#allowaccessmodification"><code>-allowaccessmodification</code></a>
option allows access permissions of classes and class members to
be broadened, opening up the opportunity to repackage all obfuscated classes:
<pre>
-repackageclasses 'myobfuscated'
-allowaccessmodification
</pre>
The obfuscated class names then look as follows:
<pre>
mycompany.myapplication.MyMain
myobfuscated.a
myobfuscated.b
myobfuscated.c
myobfuscated.d
myobfuscated.e
myobfuscated.f
</pre>
<p>
The specified target package can always be the root package. For instance:
<pre>
-repackageclasses ''
-allowaccessmodification
</pre>
The obfuscated class names are then the shortest possible names:
<pre>
mycompany.myapplication.MyMain
a
b
c
d
e
f
</pre>
<p>
Note that not all levels of obfuscation of package names may be acceptable for
all code. Notably, you may have to take into account that your application may
contain <a href="#resourcefiles">resource files</a> that have to be adapted.

<h3><a name="restructuring">Restructuring the output archives</a></h3>

In simple applications, all output classes and resources files are merged into
a single jar. For example:
<pre>
-injars  classes
-injars  in1.jar
-injars  in2.jar
-injars  in3.jar
-outjars out.jar
</pre>
<p>
This configuration merges the processed versions of the files in the
<code>classes</code> directory and the three jars into a single output jar
<code>out.jar</code>.
<p>
If you want to preserve the structure of your input jars (and/or wars, ears,
zips, or directories), you can specify an output directory (or a war, an ear,
or a zip). For example:
<pre>
-injars  in1.jar
-injars  in2.jar
-injars  in3.jar
-outjars out
</pre>
<p>
The input jars will then be reconstructed in the directory <code>out</code>,
with their original names.
<p>
You can also combine archives into higher level archives. For example:
<pre>
-injars  in1.jar
-injars  in2.jar
-injars  in3.jar
-outjars out.war
</pre>
<p>
The other way around, you can flatten the archives inside higher level
archives into simple archives:
<pre>
-injars  in.war
-outjars out.jar
</pre>
<p>
This configuration puts the processed contents of all jars inside
<code>in.war</code> (plus any other contents of <code>in.war</code>) into
<code>out.jar</code>.
<p>
If you want to combine input jars (and/or wars, ears, zips, or directories)
into output jars (and/or wars, ears, zips, or directories), you can group the
<a href="usage.html#injars"><code>-injars</code></a> and <a
href="usage.html#outjars"><code>-outjars</code></a> options. For example:
<pre>
-injars base_in1.jar
-injars base_in2.jar
-injars base_in3.jar
-outjars base_out.jar

-injars  extra_in.jar
-outjars extra_out.jar
</pre>
<p>
This configuration puts the processed results of all <code>base_in*.jar</code>
jars into <code>base_out.jar</code>, and the processed results of the
<code>extra_in.jar</code> into <code>extra_out.jar</code>. Note that only the
order of the options matters; the additional whitespace is just for clarity.
<p>
This grouping, archiving, and flattening can be arbitrarily complex. ProGuard
always tries to package output archives in a sensible way, reconstructing the
input entries as much as required.

<h3><a name="filtering">Filtering the input and the output</a></h3>

If you want even greater control, you can add
<a href="usage.html#filters">filters</a> to the input and the output,
filtering out zips, ears, wars, jars, and/or ordinary files. For example, if
you want to disregard certain files from an input jar:
<pre>
-injars  in.jar(!images/**)
-outjars out.jar
</pre>
<p>
This configuration removes any files in the <code>images</code> directory and
its subdirectories.
<p>
Such filters can be convenient for avoiding warnings about duplicate files in
the output. For example, only keeping the manifest file from a first input jar:
<pre>
-injars  in1.jar
-injars  in2.jar(!META-INF/MANIFEST.MF)
-injars  in3.jar(!META-INF/MANIFEST.MF)
-outjars out.jar
</pre>
<p>
Another useful application is speeding up the processing by ProGuard, by
disregarding a large number of irrelevant classes in the runtime library jar:
<pre>
-libraryjars &lt;java.home&gt;/lib/rt.jar(java/**,javax/**)
</pre>
<p>
The filter makes ProGuard disregard <code>com.sun.**</code> classes, for
instance , which don't affect the processing of ordinary applications.
<p>
It is also possible to filter the jars (and/or wars, ears, zips) themselves,
based on their names. For example:
<pre>
-injars  in(**/acme_*.jar;)
-outjars out.jar
</pre>
<p>
Note the semi-colon in the filter; the filter in front of it applies to jar
names. In this case, only <code>acme_*.jar</code> jars are read from the
directory <code>in</code> and its subdirectories. Filters for war names, ear
names, and zip names can be prefixed with additional semi-colons. All types of
filters can be combined. They are orthogonal.
<p>
On the other hand, you can also filter the output, in order to control what
content goes where. For example:
<pre>
-injars  in.jar
-outjars code_out.jar(**.class)
-outjars resources_out.jar
</pre>
<p>
This configuration splits the processed output, sending <code>**.class</code>
files to <code>code_out.jar</code>, and all remaining files to
<code>resources_out.jar</code>.
<p>
Again, the filtering can be arbitrarily complex, especially when combined with
grouping input and output.

<h3><a name="multiple">Processing multiple applications at once</a></h3>

You can process several dependent or independent applications (or applets,
midlets,...) in one go, in order to save time and effort. ProGuard's input and
output handling offers various ways to keep the output nicely structured.
<p>
The easiest way is to specify your input jars (and/or wars, ears, zips, and
directories) and a single output directory. ProGuard will then reconstruct the
input in this directory, using the original jar names. For example, showing
just the input and output options:
<pre>
-injars  application1.jar
-injars  application2.jar
-injars  application3.jar
-outjars processed_applications
</pre>
<p>
After processing, the directory <code>processed_applications</code> will
contain processed versions of application jars, with their original names.

<h3><a name="incremental">Incremental obfuscation</a></h3>

After having <a href="#application">processed an application</a>, e.g.
ProGuard itself, you can still incrementally add other pieces of code that
depend on it, e.g. the ProGuard GUI:
<pre>
-injars       proguardgui.jar
-outjars      proguardgui_out.jar
-injars       proguard.jar
-outjars      proguard_out.jar
-libraryjars  &lt;java.home&gt;/lib/rt.jar
-applymapping proguard.map

-keep public class proguard.gui.ProGuardGUI {
    public static void main(java.lang.String[]);
}
</pre>
<p>
We're reading both unprocessed jars as input. Their processed contents will go
to the respective output jars. The <a
href="usage.html#applymapping"><code>-applymapping</code></a> option then
makes sure the ProGuard part of the code gets the previously produced
obfuscation mapping. The final application will consist of the obfuscated
ProGuard jar and the additional obfuscated GUI jar.
<p>
The added code in this example is straightforward; it doesn't affect the
original code. The <code>proguard_out.jar</code> will be identical to the one
produced in the initial processing step. If you foresee adding more complex
extensions to your code, you should specify the options <a
href="usage.html#useuniqueclassmembernames"><code>-useuniqueclassmembernames</code></a>,
<a href="usage.html#dontshrink"><code>-dontshrink</code></a>, and <a
href="usage.html#dontoptimize"><code>-dontoptimize</code></a> <i>in the
original processing step</i>. These options ensure that the obfuscated base
jar will always remain usable without changes. You can then specify the base
jar as a library jar:
<pre>
-injars       proguardgui.jar
-outjars      proguardgui_out.jar
-libraryjars  proguard.jar
-libraryjars  &lt;java.home&gt;/lib/rt.jar
-applymapping proguard.map

-keep public class proguard.gui.ProGuardGUI {
    public static void main(java.lang.String[]);
}
</pre>

<h3><a name="microedition">Preverifying class files for Java Micro Edition</a></h3>

Even if you're not interested in shrinking, optimizing, and obfuscating your
midlets, as shown in the <a href="#midlets">midlets example</a>, you can still
use ProGuard to preverify the class files for Java Micro Edition. ProGuard
produces slightly more compact results than the traditional external
preverifier.
<pre>
-injars      in.jar
-outjars     out.jar
-libraryjars /usr/local/java/wtk2.5.2/lib/midpapi20.jar
-libraryjars /usr/local/java/wtk2.5.2/lib/cldcapi11.jar

-dontshrink
-dontoptimize
-dontobfuscate

-microedition
</pre>
<p>
We're not processing the input, just making sure the class files are
preverified by targeting them at Java Micro Edition with the <a
href="usage.html#microedition"><code>-microedition</code></a> option. Note
that we don't need any <code>-keep</code> options to specify entry points; all
class files are simply preverified.

<h3><a name="upgrade">Upgrading class files to Java 6</a></h3>

The following options upgrade class files to Java 6, by updating their
internal version numbers and preverifying them. The class files can then be
loaded more efficiently by the Java 6 Virtual Machine.
<pre>
-injars      in.jar
-outjars     out.jar
-libraryjars &lt;java.home&gt;/lib/rt.jar

-dontshrink
-dontoptimize
-dontobfuscate

-target 1.6
</pre>
<p>
We're not processing the input, just retargeting the class files with the <a
href="usage.html#target"><code>-target</code></a> option. They will
automatically be preverified for Java 6 as a result. Note that we don't need
any <code>-keep</code> options to specify entry points; all class files are
simply updated and preverified.

<h3><a name="deadcode">Finding dead code</a></h3>

These options list unused classes, fields, and methods in the application
<code>mypackage.MyApplication</code>:
<pre>
-injars      in.jar
-libraryjars &lt;java.home&gt;/lib/rt.jar

-dontoptimize
-dontobfuscate
-dontpreverify
-printusage

-keep public class mypackage.MyApplication {
    public static void main(java.lang.String[]);
}
</pre>
<p>
We're not specifying an output jar, just printing out some results. We're
saving some processing time by skipping the other processing steps.
<p>
The java compiler inlines primitive constants and String constants
(<code>static final</code> fields). ProGuard would therefore list such fields
as not being used in the class files that it analyzes, even if they <i>are</i>
used in the source files. We can add a <a
href="usage.html#keepclassmembers"><code>-keepclassmembers</code></a> option
that keeps those fields a priori, in order to avoid having them listed:
<pre>
-keepclassmembers class * {
    static final %                *;
    static final java.lang.String *;
}
</pre>

<h3><a name="structure">Printing out the internal structure of class files</a></h3>

These options print out the internal structure of all class files in the input
jar:
<pre>
-injars in.jar

-dontshrink
-dontoptimize
-dontobfuscate
-dontpreverify

-dump
</pre>
<p>
Note how we don't need to specify the Java run-time jar, because we're not
processing the input jar at all.

<h3><a name="annotated">Using annotations to configure ProGuard</a></h3>

The traditional ProGuard configuration allows to keep a clean separation
between the code and the configuration for shrinking, optimization, and
obfuscation. However, it is also possible to define specific annotations,
and then annotate the code to configure the processing.
<p>
You can find a set of such predefined annotations in the directory
<code>examples/annotations/lib</code> in the ProGuard distribution.
The annotation classes are defined in <code>annotations.jar</code>. The
corresponding ProGuard configuration (or meta-configuration, if you prefer)
is specified in <code>annotations.pro</code>. With these files, you can start
annotating your code. For instance, a java source file
<code>Application.java</code> can be annotated as follows:
<pre>
@KeepApplication
public class Application {
  ....
}
</pre>
<p>
The ProGuard configuration file for the application can then be simplified by
leveraging off these annotations:
<pre>
-injars      in.jar
-outjars     out.jar
-libraryjars &lt;java.home&gt;/lib/rt.jar

-include lib/annotations.pro
</pre>
<p>
The annotations are effectively replacing the application-dependent
<code>-keep</code> options. You may still wish to add traditional
<code>-keep</code> options for processing <a href="#native">native
methods</a>, <a href="#enumerations">enumerations</a>, <a
href="#serializable">serializable classes</a>, and <a
href="#annotations">annotations</a>.
<p>
The directory <code>examples/annotations</code> contains more examples that
illustrate some of the possibilities.

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