react-native/website/versioned_docs/0.21/android-building-from-source.md

id, title, original_id

id	title	original_id
version-0.21-android-building-from-source	android-building-from-source	android-building-from-source

Building React Native from source #

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You will need to build React Native from source if you want to work on a new feature/bug fix, try out the latest features which are not released yet, or maintain your own fork with patches that cannot be merged to the core.

Prerequisites #

Assuming you have the Android SDK installed, run android to open the Android SDK Manager.

Make sure you have the following installed:

1. Android SDK version 23 (compileSdkVersion in build.gradle)
2. SDK build tools version 23.0.1 (buildToolsVersion in build.gradle)
3. Android Support Repository >= 17 (for Android Support Library)
4. Android NDK (download & extraction instructions here)

Point Gradle to your Android SDK: either have $ANDROID_SDK and $ANDROID_NDK defined, or create a local.properties file in the root of your react-native checkout with the following contents:

sdk.dir=absolute_path_to_android_sdk ndk.dir=absolute_path_to_android_ndk

Example:

sdk.dir=/Users/your_unix_name/android-sdk-macosx ndk.dir=/Users/your_unix_name/android-ndk/android-ndk-r10e

Building the source #

1. Installing the fork #

First, you need to install react-native from your fork. For example, to install the master branch from the official repo, run the following:

npm install --save github:facebook/react-native#master

Alternatively, you can clone the repo to your node_modules directory and run npm install inside the cloned repo.

2. Adding gradle dependencies #

Add gradle-download-task as dependency in android/build.gradle:

... dependencies { classpath 'com.android.tools.build:gradle:1.3.1' classpath 'de.undercouch:gradle-download-task:2.0.0'

   <span class="token comment" spellcheck="true"> // NOTE: Do not place your application dependencies here; they belong

// in the individual module build.gradle files } ...

3. Adding the :ReactAndroid project #

Add the :ReactAndroid project in android/settings.gradle:

... include ':ReactAndroid'

project(':ReactAndroid').projectDir = new File( rootProject.projectDir, '../node_modules/react-native/ReactAndroid') ...

Modify your android/app/build.gradle to use the :ReactAndroid project instead of the pre-compiled library, e.g. - replace compile 'com.facebook.react:react-native:0.16.+' with compile project(':ReactAndroid'):

... dependencies { compile fileTree(dir: 'libs', include: ['*.jar']) compile 'com.android.support:appcompat-v7:23.0.1'

compile <span class="token function">project<span class="token punctuation">(</span></span><span class="token string">':ReactAndroid'</span><span class="token punctuation">)</span>

<span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>

} ...

4. Making 3rd-party modules use your fork #

If you use 3rd-party React Native modules, you need to override their dependencies so that they don't bundle the pre-compiled library. Otherwise you'll get an error while compiling - Error: more than one library with package name 'com.facebook.react'.

Modify your android/app/build.gradle and replace compile project(':react-native-custom-module') with:

compile(project(':react-native-custom-module')) { exclude group: 'com.facebook.react', module: 'react-native' }

Additional notes #

Building from source can take a long time, especially for the first build, as it needs to download 200 MB of artifacts and compile the native code. Every time you update the react-native version from your repo, the build directory may get deleted, and all the files are re-downloaded. To avoid this, you might want to change your build directory path by editing the /.gradle/init.gradle file:

gradle.projectsLoaded { rootProject.allprojects { buildDir = "/path/to/build/directory/${rootProject.name}/${project.name}" } }

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