| page.title=Build System Overview |
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| @jd:body |
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| <div id="qv-wrapper"> |
| <div id="qv"> |
| <h2>In this document</h2> |
| <ol> |
| <li><a href="#detailed-build">A Detailed Look at the Build Process</a> </li> |
| </ol> |
| <h2>See also</h2> |
| <ul> |
| <li><a href="{@docRoot}sdk/installing/studio.html"> |
| Getting Started with Android Studio</a></li> |
| <li><a href="{@docRoot}tools/studio/index.html">Android Studio Basics</a></li> |
| </div> |
| </div> |
| |
| <a class="notice-developers-video" href="https://www.youtube.com/watch?v=LCJAgPkpmR0#t=504"> |
| <div> |
| <h3>Video</h3> |
| <p>The New Android SDK Build System</p> |
| </div> |
| </a> |
| |
| <p>The Android build system is the toolkit you use to build, test, run and package |
| your apps. The build system can run as an integrated tool from the Android Studio menu and |
| independently from the command line. You can use the features of the build system to:</p> |
| |
| <ul> |
| <li>Customize, configure, and extend the build process.</li> |
| <li>Create multiple APKs for your app with different features using the same project and |
| modules.</li> |
| <li>Reuse code and resources across source sets.</li> |
| </ul> |
| |
| <p>The flexibility of the Android build system enables you to achieve all of this without |
| modifying your app's core source files. To build an Android Studio project, see |
| <a href="{@docRoot}tools/building/building-studio.html">Building and Running from Android Studio</a>. |
| To configure custom build settings in an Android Studio project, see |
| <a href="{@docRoot}tools/building/configuring-gradle.html">Configuring Gradle Builds</a>.</p> |
| |
| |
| <h2 id="detailed-build">A Detailed Look at the Build Process</h2> |
| |
| <p>The build process involves many tools and processes that generate intermediate files on the |
| way to producing an <code>.apk</code>. If you are developing in Android Studio, the complete build |
| process is done every time you run the Gradle build task for your project or modules. The build |
| process is very flexible so it's useful, however, to understand what is happening under the hood |
| since much of the build process is configurable and extensible. The following diagram depicts the |
| different tools and processes that are involved in a build:</p> |
| |
| <img src="{@docRoot}images/build.png" /> |
| |
| <p>The general process for a typical build is outlined below. The build system merges all the |
| resources from the configured product flavors, build types, and dependencies. If different |
| folders contain resources with the same name or setting, the following override priority order is: |
| dependencies override build types, which override product flavors, which override the main source |
| directory.</p> |
| |
| <ul> |
| |
| <li>The Android Asset Packaging Tool (aapt) takes your application resource files, such as the |
| <code>AndroidManifest.xml</code> file and the XML files for your Activities, and compiles them. |
| An <code>R.java</code> is also produced so you can reference your resources from your Java code.</li> |
| |
| <li>The aidl tool converts any <code>.aidl</code> interfaces that you have into Java interfaces.</li> |
| |
| <li>All of your Java code, including the <code>R.java</code> and <code>.aidl</code> files, are |
| compiled by the Java compiler and .class files are output.</li> |
| |
| <li>The dex tool converts the .class files to Dalvik byte code. Any 3rd party libraries and |
| .class files that you have included in your module build are also converted into <code>.dex</code> |
| files so that they can be packaged into the final <code>.apk</code> file.</li> |
| |
| <li>All non-compiled resources (such as images), compiled resources, and the .dex files are |
| sent to the apkbuilder tool to be packaged into an <code>.apk</code> file.</li> |
| |
| <li>Once the <code>.apk</code> is built, it must be signed with either a debug or release key |
| before it can be installed to a device.</li> |
| |
| <li>Finally, if the application is being signed in release mode, you must align the |
| <code>.apk</code> with the zipalign tool. Aligning the final <code>.apk</code> decreases memory |
| usage when the application is -running on a device.</li> |
| </ul> |
| |
| <p class="note"><b>Note:</b> Apps are limited to a 64K method reference limit. If your app reaches |
| this limit, the build process outputs the following error message: |
| |
| <pre>Unable to execute dex: method ID not in [0, 0xffff]: 65536.</pre> |
| |
| To avoid this error, see |
| <a href="{@docRoot}tools/building/multidex.html">Building Apps with Over 64K Methods</a>. |
| </p> |
| |
| |
| <h3>Build output</h3> |
| |
| <p>The build generates an APK for each build variant in the <code>app/build</code> folder: |
| the <code>app/build/outputs/apk/</code> directory contains packages named |
| <code>app-<flavor>-<buildtype>.apk</code>; for example, <code>app-full-release.apk</code> and |
| <code>app-demo-debug.apk</code>.</p> |
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