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 <html devsite>
   <head>
     <title>Compiling with Jack</title>
     <meta name="project_path" value="/_project.yaml" />
     <meta name="book_path" value="/_book.yaml" />
   </head>
   <body>
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       Copyright 2017 The Android Open Source Project

       Licensed under the Apache License, Version 2.0 (the "License");
       you may not use this file except in compliance with the License.
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           http://www.apache.org/licenses/LICENSE-2.0

       Unless required by applicable law or agreed to in writing, software
       distributed under the License is distributed on an "AS IS" BASIS,
       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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 <aside class="warning"><strong>Warning:</strong> As of this
 <a href="https://android-developers.googleblog.com/2017/03/future-of-java-8-language-feature.html" class="external">March
 14, 2017 announcement</a>, the Jack toolchain is deprecated. Jack was the default Android
 build toolchain for Android 6.0&ndash;8.1.</aside>

 <p>Jack is an Android toolchain that compiled Java source into Android dex
 bytecode. You don’t have to do anything differently to
 use Jack&mdash;just use your standard makefile commands to compile the tree or
 your project. Android 8.1 is the last release that uses Jack.</p>

 <h2 id="overview">About Jack</h2>
 <p>Jack works as follows:</p>

 <img src="../images/jack_overview.png" alt="Jack overview"/>
 <figcaption><strong>Figure 1.</strong> Jack overview.</figcaption>

 <h3 id=jack_library>Jack library format</h3>

 <p>Jack has its own .jack file format that contains the pre-compiled dex code
 for the library, allowing for faster compilation (pre-dex).</p>

 <img src="../images/jack_library.png" alt="Jack library file contents"/>
 <figcaption><strong>Figure 2.</strong> Jack library file contents.</figcaption>

 <h3 id=jill>Jill</h3>

 <p>The Jill tool translates the existing .jar libraries into the new library
 format, as shown below.</p>

 <img src="../images/jack_jill.png" alt="Importing .jar libraries with Jill"/>
 <figcaption><strong>Figure 3.</strong> Workflow to import an existing .jar
 library.</figcaption>

 <h2 id=using_jack>Jack compilation server</h2>

 <aside class="note"><strong>Note:</strong> The following instructions apply only
 to using Jack in Android 6.x; for instructions on using Jack in Android 7.x and
 8.x, refer to
 <a href="https://android.googlesource.com/platform/prebuilts/sdk/+/master/tools/README-jack-server.md" class="external">Jack
 server documentation</a>.</aside>

 <p>The first time Jack is used, it launches a local Jack compilation server on
 your computer. This server:</p>

 <ul>
 <li>Brings an intrinsic speedup because it avoids launching a new host JRE JVM,
 loading Jack code, initializing Jack, and warming up the JIT at each
 compilation. It also provides very good compilation times during small
 compilations (e.g. in incremental mode).</li>
 <li>Is a short-term solution to control the number of parallel Jack
 compilations. It avoids overloading your computer (memory or disk issue) because
 it limits the number of parallel compilations.</li>
 </ul>

 <p>The Jack server shuts itself down after an idle time without any compilation.
 It uses two TCP ports on the localhost interface and is not available
 externally. All parameters (number of parallel compilations, timeout, ports
 number, etc.) can be modified by editing the <code>$HOME/.jack</code> file.</p>

 <h3 id=home_jack_file>$HOME/.jack file</h3>

 <p>The <code>$HOME/.jack</code> file contains the following settings for Jack
 server variables in a full bash syntax:</p>

 <ul>
 <li><code>SERVER=true</code>. Enable the server feature of Jack.</li>
 <li><code>SERVER_PORT_SERVICE=8072</code>. Set the TCP port number of the server
 for compilation purposes.</li>
 <li><code>SERVER_PORT_ADMIN=8073</code>. Set the TCP port number of the server
 for admin purposes.</li>
 <li><code>SERVER_COUNT=1</code>. Unused.
 <li><code>SERVER_NB_COMPILE=4</code>. Set the maximum number of allowed parallel
 compilations.</li>
 <li><code>SERVER_TIMEOUT=60</code>. Set the number of idle seconds the server
 must wait without any compilation before shutting itself down.</li>
 <li><code>SERVER_LOG=${SERVER_LOG:=$SERVER_DIR/jack-$SERVER_PORT_SERVICE.log}</code>.
 Set the file where server logs are written. By default, this variable can be
 overloaded by an environment variable.</li>
 <li><code>JACK_VM_COMMAND=${JACK_VM_COMMAND:=java}</code>. Set the default
 command used to launch a JVM on the host. By default, this variable can be
 overloaded by environment variable.</li>
 </ul>

 <h3 id=jack_troubleshooting>Troubleshooting Jack compilations</h3>

 <table>
 <tr>
 <th>Problem</th>
 <th>Action</th>
 </tr>
 <tr>
 <td>Your computer becomes unresponsive during compilation or you experience
 Jack compilations failing on “Out of memory error”</td>
 <td>You can improve the situation by reducing the number of simultaneous Jack
 compilations by editing <code>$HOME/.jack</code> and changing
 <code>SERVER_NB_COMPILE</code> to a lower value.</td>
 </tr>
 <tr>
 <td>Compilations are failing on “Cannot launch background server”</td>
 <td>The most likely cause is TCP ports are already used on your computer. Change
 ports by editing <code>$HOME/.jack</code> (<code>SERVER_PORT_SERVICE</code> and
 <code>SERVER_PORT_ADMIN</code> variables).

 <br><br>If it doesn’t solve the problem, report the error (be sure to attach
 your compilation log and the <a href="#jack_log">Jack server log</a>). To
 unblock the situation, disable the Jack compilation server by editing
 <code>$HOME/.jack</code> and changing <code>SERVER</code> to false.
 Unfortunately this will significantly slow down your compilation and may force
 you to launch <code>make -j</code> with load control (option <code>-l</code>
 of <code>make</code>).
 </td>
 </tr>
 <tr>
 <td>Compilation gets stuck without any progress</td>
 <td>Report and provide the following information when possible:
 <br>
 <ul>
 <li>Command line at which you are stuck.</li>
 <li>Output of this command line.</li>
 <li>Result of executing <code>jack-admin server-stat</code>.</li>
 <li><code>$HOME/.jack</code> file.</li>
 <li>Content of the <a href="#jack_log">Jack server log</a> with the server state
 dumped. To get the server log:
  <ul>
  <li>Find the Jack background server process by running
  <code>jack-admin list-server</code>.</li>
  <li>Send a <code>kill -3</code> command to this server to dump its state into
  the log file.</li>
  </ul>
 </li>
 <li>Result of executing <code>ls -lR $TMPDIR/jack-$USER</code>.</li>
 <li>Result of running <code>ps j -U $USER</code>.</li>
 </ul>

 To unblock the situation, kill the Jack background server using
 <code>jack-admin kill-server</code>) then remove the temporary directories
 contained in <code>jack-$USER</code> of your temporary directory
 (<code>/tmp</code> or <code>$TMPDIR</code>).
 </td>
 </tr>
 </table>

 <h3 id="jack_log">Finding the Jack log</h3>
 If you ran a <code>make</code> command with a dist target, the Jack log is
 located at <code>$ANDROID_BUILD_TOP/out/dist/logs/jack-server.log</code>.
 Otherwise, you can find the log by running <code>jack-admin server-log</code>.
 In case of reproducible Jack failures, you can get a more detailed log by
 setting the following variable:</p>

 <pre class="devsite-terminal devsite-click-to-copy">
 export ANDROID_JACK_EXTRA_ARGS="--verbose debug --sanity-checks on -D sched.runner=single-threaded"
 </pre>

 <p>Use standard makefile commands to compile the tree (or your project) and
 attach standard output and error. To remove detailed build logs, run:</p>

 <pre class="devsite-terminal devsite-click-to-copy">
 unset ANDROID_JACK_EXTRA_ARGS
 </pre>

 <h3 id=jack_limitations>Jack limitations</h3>

 <ul>
 <li>By default, the Jack server is mono-user and can be used by only one user on
 a computer. To support additional users, select different port numbers for each
 user and adjust <code>SERVER_NB_COMPILE</code> accordingly. You can also disable
 the Jack server by setting <code>SERVER=false</code> in
 <code>$HOME/.jack</code>.</li>
 <li>CTS compilation is slow due to current <code>vm-tests-tf</code> integration.
 <li>Bytecode manipulation tools (such as JaCoCo) are not supported.</li>
 </ul>

 <h2 id=using_jack_features>Using Jack</h2>

 <p>Jack supports Java programming language 1.7 and integrates the additional
 features described below.</p>

 <h3 id=predexing>Predexing</h3>

 <p>When generating a Jack library file, the <code>.dex</code> of the library is
 generated and stored inside the <code>.jack</code> library file as a pre-dex.
 When compiling, Jack reuses the pre-dex from each library. All libraries are
 pre-dexed:</p>

 <img src="../images/jack_predex.png" alt="Jack libraries with pre-dex" />
 <figcaption><strong>Figure 4.</strong> Jack libraries with pre-dex.</figcaption>

 <p>Jack does not reuse the library pre-dex if shrinking, obfuscation, or
 repackaging is used in the compilation.</p>

 <h3 id=incremental_compilation>Incremental compilation</h3>

 <p>Incremental compilation means that only the components touched since the last
 compilation (and their dependencies) are recompiled. Incremental compilation can
 be significantly faster than a full compilation when changes are limited to a
 set of components.</p>

 <p>Incremental compilation is not enabled by default (and is automatically
 deactivated when shrinking, obfuscation, repackaging or multi-dex legacy is
 enabled). To enable incremental builds, add the following line to the
 <code>Android.mk</code> file of the project you want to build incrementally:</p>

 <pre class="devsite-click-to-copy">LOCAL_JACK_ENABLED := incremental</pre>

 <aside class="note"><strong>Note:</strong> If some dependencies are not built
 the first time you build your project with Jack, use <code>mma</code> to build
 them. After doing so you can use the standard build command.</aside>

 <h3 id=shrinking_and_obfuscation>Shrinking and obfuscation</h3>

 <p>Jack uses proguard configuration files to enable shrinking and obfuscation.</p>

 <p>Common options include the following:</p>

 <ul>
   <li> <code>@</code>
   <li> <code>-include</code>
   <li> <code>-basedirectory</code>
   <li> <code>-injars</code>
   <li> <code>-outjars // only 1 output jar supported</code>
   <li> <code>-libraryjars</code>
   <li> <code>-keep</code>
   <li> <code>-keepclassmembers</code>
   <li> <code>-keepclasseswithmembers</code>
   <li> <code>-keepnames</code>
   <li> <code>-keepclassmembernames</code>
   <li> <code>-keepclasseswithmembernames</code>
   <li> <code>-printseeds</code>
 </ul>

 <p>Shrinking options include the following:</p>

 <ul>
   <li><code>-dontshrink</code>
 </ul>

 <p>Obfuscation options include the following:</p>

 <ul>
   <li> <code>-dontobfuscate</code>
   <li> <code>-printmapping</code>
   <li> <code>-applymapping</code>
   <li> <code>-obfuscationdictionary</code>
   <li> <code>-classobfuscationdictionary</code>
   <li> <code>-packageobfuscationdictionary</code>
   <li> <code>-useuniqueclassmembernames</code>
   <li> <code>-dontusemixedcaseclassnames</code>
   <li> <code>-keeppackagenames</code>
   <li> <code>-flattenpackagehierarchy</code>
   <li> <code>-repackageclasses</code>
   <li> <code>-keepattributes</code>
   <li> <code>-adaptclassstrings</code>
 </ul>

 <p>Ignored options include the following:</p>

 <ul>
   <li> <code>-dontoptimize // Jack does not optimize</code>
   <li> <code>-dontpreverify // Jack does not preverify</code>
   <li> <code>-skipnonpubliclibraryclasses</code>
   <li> <code>-dontskipnonpubliclibraryclasses</code>
   <li> <code>-dontskipnonpubliclibraryclassmembers</code>
   <li> <code>-keepdirectories</code>
   <li> <code>-target</code>
   <li> <code>-forceprocessing</code>
   <li> <code>-printusage</code>
   <li> <code>-whyareyoukeeping</code>
   <li> <code>-optimizations</code>
   <li> <code>-optimizationpasses</code>
   <li> <code>-assumenosideeffects</code>
   <li> <code>-allowaccessmodification</code>
   <li> <code>-mergeinterfacesaggressively</code>
   <li> <code>-overloadaggressively</code>
   <li> <code>-microedition</code>
   <li> <code>-verbose</code>
   <li> <code>-dontnote</code>
   <li> <code>-dontwarn</code>
   <li> <code>-ignorewarnings</code>
   <li> <code>-printconfiguration</code>
   <li> <code>-dump</code>
 </ul>

 <aside class="note"><strong>Note:</strong> Other options will generate an
 error.</aside>

 <h3 id=repackaging>Repackaging</h3>

 <p>Jack uses jarjar configuration files to do repackaging. While Jack is
 compatible with "rule" rule types, it is not compatible with "zap" or
 "keep" rule types.</p>

 <h3 id=multidex_support>Multidex support</h3>

 <p>Jack offers native and legacy multidex support. Since dex files are limited
 to 65K methods, apps with over 65K methods must be split into multiple dex
 files. For more details, refer to
 <a href="http://developer.android.com/tools/building/multidex.html" class="external">Building
 Apps with Over 65K Methods</a>.</p>

   </body>
 </html>
	<html devsite>
	<head>
	<title>Compiling with Jack</title>
	<meta name="project_path" value="/_project.yaml" />
	<meta name="book_path" value="/_book.yaml" />
	</head>
	<body>
	<!--
	Copyright 2017 The Android Open Source Project

	Licensed under the Apache License, Version 2.0 (the "License");
	you may not use this file except in compliance with the License.
	You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	See the License for the specific language governing permissions and
	limitations under the License.
	-->

	<aside class="warning"><strong>Warning:</strong> As of this
	<a href="https://android-developers.googleblog.com/2017/03/future-of-java-8-language-feature.html" class="external">March
	14, 2017 announcement</a>, the Jack toolchain is deprecated. Jack was the default Android
	build toolchain for Android 6.0–8.1.</aside>

	<p>Jack is an Android toolchain that compiled Java source into Android dex
	bytecode. You don’t have to do anything differently to
	use Jack—just use your standard makefile commands to compile the tree or
	your project. Android 8.1 is the last release that uses Jack.</p>

	<h2 id="overview">About Jack</h2>
	<p>Jack works as follows:</p>

	<img src="../images/jack_overview.png" alt="Jack overview"/>
	<figcaption><strong>Figure 1.</strong> Jack overview.</figcaption>

	<h3 id=jack_library>Jack library format</h3>

	<p>Jack has its own .jack file format that contains the pre-compiled dex code
	for the library, allowing for faster compilation (pre-dex).</p>

	<img src="../images/jack_library.png" alt="Jack library file contents"/>
	<figcaption><strong>Figure 2.</strong> Jack library file contents.</figcaption>

	<h3 id=jill>Jill</h3>

	<p>The Jill tool translates the existing .jar libraries into the new library
	format, as shown below.</p>

	<img src="../images/jack_jill.png" alt="Importing .jar libraries with Jill"/>
	<figcaption><strong>Figure 3.</strong> Workflow to import an existing .jar
	library.</figcaption>

	<h2 id=using_jack>Jack compilation server</h2>

	<aside class="note"><strong>Note:</strong> The following instructions apply only
	to using Jack in Android 6.x; for instructions on using Jack in Android 7.x and
	8.x, refer to
	<a href="https://android.googlesource.com/platform/prebuilts/sdk/+/master/tools/README-jack-server.md" class="external">Jack
	server documentation</a>.</aside>

	<p>The first time Jack is used, it launches a local Jack compilation server on
	your computer. This server:</p>

	<ul>
	<li>Brings an intrinsic speedup because it avoids launching a new host JRE JVM,
	loading Jack code, initializing Jack, and warming up the JIT at each
	compilation. It also provides very good compilation times during small
	compilations (e.g. in incremental mode).</li>
	<li>Is a short-term solution to control the number of parallel Jack
	compilations. It avoids overloading your computer (memory or disk issue) because
	it limits the number of parallel compilations.</li>
	</ul>

	<p>The Jack server shuts itself down after an idle time without any compilation.
	It uses two TCP ports on the localhost interface and is not available
	externally. All parameters (number of parallel compilations, timeout, ports
	number, etc.) can be modified by editing the <code>$HOME/.jack</code> file.</p>

	<h3 id=home_jack_file>$HOME/.jack file</h3>

	<p>The <code>$HOME/.jack</code> file contains the following settings for Jack
	server variables in a full bash syntax:</p>

	<ul>
	<li><code>SERVER=true</code>. Enable the server feature of Jack.</li>
	<li><code>SERVER_PORT_SERVICE=8072</code>. Set the TCP port number of the server
	for compilation purposes.</li>
	<li><code>SERVER_PORT_ADMIN=8073</code>. Set the TCP port number of the server
	for admin purposes.</li>
	<li><code>SERVER_COUNT=1</code>. Unused.
	<li><code>SERVER_NB_COMPILE=4</code>. Set the maximum number of allowed parallel
	compilations.</li>
	<li><code>SERVER_TIMEOUT=60</code>. Set the number of idle seconds the server
	must wait without any compilation before shutting itself down.</li>
	<li><code>SERVER_LOG=${SERVER_LOG:=$SERVER_DIR/jack-$SERVER_PORT_SERVICE.log}</code>.
	Set the file where server logs are written. By default, this variable can be
	overloaded by an environment variable.</li>
	<li><code>JACK_VM_COMMAND=${JACK_VM_COMMAND:=java}</code>. Set the default
	command used to launch a JVM on the host. By default, this variable can be
	overloaded by environment variable.</li>
	</ul>

	<h3 id=jack_troubleshooting>Troubleshooting Jack compilations</h3>

	<table>
	<tr>
	<th>Problem</th>
	<th>Action</th>
	</tr>
	<tr>
	<td>Your computer becomes unresponsive during compilation or you experience
	Jack compilations failing on “Out of memory error”</td>
	<td>You can improve the situation by reducing the number of simultaneous Jack
	compilations by editing <code>$HOME/.jack</code> and changing
	<code>SERVER_NB_COMPILE</code> to a lower value.</td>
	</tr>
	<tr>
	<td>Compilations are failing on “Cannot launch background server”</td>
	<td>The most likely cause is TCP ports are already used on your computer. Change
	ports by editing <code>$HOME/.jack</code> (<code>SERVER_PORT_SERVICE</code> and
	<code>SERVER_PORT_ADMIN</code> variables).

	<br><br>If it doesn’t solve the problem, report the error (be sure to attach
	your compilation log and the <a href="#jack_log">Jack server log</a>). To
	unblock the situation, disable the Jack compilation server by editing
	<code>$HOME/.jack</code> and changing <code>SERVER</code> to false.
	Unfortunately this will significantly slow down your compilation and may force
	you to launch <code>make -j</code> with load control (option <code>-l</code>
	of <code>make</code>).
	</td>
	</tr>
	<tr>
	<td>Compilation gets stuck without any progress</td>
	<td>Report and provide the following information when possible:
	<br>
	<ul>
	<li>Command line at which you are stuck.</li>
	<li>Output of this command line.</li>
	<li>Result of executing <code>jack-admin server-stat</code>.</li>
	<li><code>$HOME/.jack</code> file.</li>
	<li>Content of the <a href="#jack_log">Jack server log</a> with the server state
	dumped. To get the server log:
	<ul>
	<li>Find the Jack background server process by running
	<code>jack-admin list-server</code>.</li>
	<li>Send a <code>kill -3</code> command to this server to dump its state into
	the log file.</li>
	</ul>
	</li>
	<li>Result of executing <code>ls -lR $TMPDIR/jack-$USER</code>.</li>
	<li>Result of running <code>ps j -U $USER</code>.</li>
	</ul>

	To unblock the situation, kill the Jack background server using
	<code>jack-admin kill-server</code>) then remove the temporary directories
	contained in <code>jack-$USER</code> of your temporary directory
	(<code>/tmp</code> or <code>$TMPDIR</code>).
	</td>
	</tr>
	</table>

	<h3 id="jack_log">Finding the Jack log</h3>
	If you ran a <code>make</code> command with a dist target, the Jack log is
	located at <code>$ANDROID_BUILD_TOP/out/dist/logs/jack-server.log</code>.
	Otherwise, you can find the log by running <code>jack-admin server-log</code>.
	In case of reproducible Jack failures, you can get a more detailed log by
	setting the following variable:</p>

	<pre class="devsite-terminal devsite-click-to-copy">
	export ANDROID_JACK_EXTRA_ARGS="--verbose debug --sanity-checks on -D sched.runner=single-threaded"
	</pre>

	<p>Use standard makefile commands to compile the tree (or your project) and
	attach standard output and error. To remove detailed build logs, run:</p>

	<pre class="devsite-terminal devsite-click-to-copy">
	unset ANDROID_JACK_EXTRA_ARGS
	</pre>

	<h3 id=jack_limitations>Jack limitations</h3>

	<ul>
	<li>By default, the Jack server is mono-user and can be used by only one user on
	a computer. To support additional users, select different port numbers for each
	user and adjust <code>SERVER_NB_COMPILE</code> accordingly. You can also disable
	the Jack server by setting <code>SERVER=false</code> in
	<code>$HOME/.jack</code>.</li>
	<li>CTS compilation is slow due to current <code>vm-tests-tf</code> integration.
	<li>Bytecode manipulation tools (such as JaCoCo) are not supported.</li>
	</ul>

	<h2 id=using_jack_features>Using Jack</h2>

	<p>Jack supports Java programming language 1.7 and integrates the additional
	features described below.</p>

	<h3 id=predexing>Predexing</h3>

	<p>When generating a Jack library file, the <code>.dex</code> of the library is
	generated and stored inside the <code>.jack</code> library file as a pre-dex.
	When compiling, Jack reuses the pre-dex from each library. All libraries are
	pre-dexed:</p>

	<img src="../images/jack_predex.png" alt="Jack libraries with pre-dex" />
	<figcaption><strong>Figure 4.</strong> Jack libraries with pre-dex.</figcaption>

	<p>Jack does not reuse the library pre-dex if shrinking, obfuscation, or
	repackaging is used in the compilation.</p>

	<h3 id=incremental_compilation>Incremental compilation</h3>

	<p>Incremental compilation means that only the components touched since the last
	compilation (and their dependencies) are recompiled. Incremental compilation can
	be significantly faster than a full compilation when changes are limited to a
	set of components.</p>

	<p>Incremental compilation is not enabled by default (and is automatically
	deactivated when shrinking, obfuscation, repackaging or multi-dex legacy is
	enabled). To enable incremental builds, add the following line to the
	<code>Android.mk</code> file of the project you want to build incrementally:</p>

	<pre class="devsite-click-to-copy">LOCAL_JACK_ENABLED := incremental</pre>

	<aside class="note"><strong>Note:</strong> If some dependencies are not built
	the first time you build your project with Jack, use <code>mma</code> to build
	them. After doing so you can use the standard build command.</aside>

	<h3 id=shrinking_and_obfuscation>Shrinking and obfuscation</h3>

	<p>Jack uses proguard configuration files to enable shrinking and obfuscation.</p>

	<p>Common options include the following:</p>

	<ul>
	<li> <code>@</code>
	<li> <code>-include</code>
	<li> <code>-basedirectory</code>
	<li> <code>-injars</code>
	<li> <code>-outjars // only 1 output jar supported</code>
	<li> <code>-libraryjars</code>
	<li> <code>-keep</code>
	<li> <code>-keepclassmembers</code>
	<li> <code>-keepclasseswithmembers</code>
	<li> <code>-keepnames</code>
	<li> <code>-keepclassmembernames</code>
	<li> <code>-keepclasseswithmembernames</code>
	<li> <code>-printseeds</code>
	</ul>

	<p>Shrinking options include the following:</p>

	<ul>
	<li><code>-dontshrink</code>
	</ul>

	<p>Obfuscation options include the following:</p>

	<ul>
	<li> <code>-dontobfuscate</code>
	<li> <code>-printmapping</code>
	<li> <code>-applymapping</code>
	<li> <code>-obfuscationdictionary</code>
	<li> <code>-classobfuscationdictionary</code>
	<li> <code>-packageobfuscationdictionary</code>
	<li> <code>-useuniqueclassmembernames</code>
	<li> <code>-dontusemixedcaseclassnames</code>
	<li> <code>-keeppackagenames</code>
	<li> <code>-flattenpackagehierarchy</code>
	<li> <code>-repackageclasses</code>
	<li> <code>-keepattributes</code>
	<li> <code>-adaptclassstrings</code>
	</ul>

	<p>Ignored options include the following:</p>

	<ul>
	<li> <code>-dontoptimize // Jack does not optimize</code>
	<li> <code>-dontpreverify // Jack does not preverify</code>
	<li> <code>-skipnonpubliclibraryclasses</code>
	<li> <code>-dontskipnonpubliclibraryclasses</code>
	<li> <code>-dontskipnonpubliclibraryclassmembers</code>
	<li> <code>-keepdirectories</code>
	<li> <code>-target</code>
	<li> <code>-forceprocessing</code>
	<li> <code>-printusage</code>
	<li> <code>-whyareyoukeeping</code>
	<li> <code>-optimizations</code>
	<li> <code>-optimizationpasses</code>
	<li> <code>-assumenosideeffects</code>
	<li> <code>-allowaccessmodification</code>
	<li> <code>-mergeinterfacesaggressively</code>
	<li> <code>-overloadaggressively</code>
	<li> <code>-microedition</code>
	<li> <code>-verbose</code>
	<li> <code>-dontnote</code>
	<li> <code>-dontwarn</code>
	<li> <code>-ignorewarnings</code>
	<li> <code>-printconfiguration</code>
	<li> <code>-dump</code>
	</ul>

	<aside class="note"><strong>Note:</strong> Other options will generate an
	error.</aside>

	<h3 id=repackaging>Repackaging</h3>

	<p>Jack uses jarjar configuration files to do repackaging. While Jack is
	compatible with "rule" rule types, it is not compatible with "zap" or
	"keep" rule types.</p>

	<h3 id=multidex_support>Multidex support</h3>

	<p>Jack offers native and legacy multidex support. Since dex files are limited
	to 65K methods, apps with over 65K methods must be split into multiple dex
	files. For more details, refer to
	<a href="http://developer.android.com/tools/building/multidex.html" class="external">Building
	Apps with Over 65K Methods</a>.</p>

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