How to build an android library with Android Studio and gradle

Question

I am trying to migrate a project from Eclipse but nothing I have tried is working  In Eclipse I have 3 projects  2 android app projects and 1 android library project   The 2 app projects depend on the library project  When I do the gradle export I get 3 projects that don t work  I am open to restructuring the project but haven t found any documentation on how this should be done   Is there a way to make the 3 projects that Eclipse exports work together  Am I better off restructuring things and if so is documentation for how this should be done   Update  I have uploaded the entire project to GitHub https   github com respectTheCode android-studio-library-example  Update 1  Based the suggestions from Padma Kumar this is what I have tried    Create a new Project called MyApp Click File  gt  New Module  choose Android Library and name it MyLib Click Build  gt  Make Project   The build fails with this error  Module  MyLib  was fully rebuilt due to project configuration dependencies changes Compilation completed with 1 error and 0 warnings in 19 sec 1 error 0 warnings      MyApp MyLib build bundles debug AndroidManifest xml Gradle   lt manifest gt  does not have package attribute    I then added a package attribute to the manifest making it   lt manifest xmlns android  http   schemas android com apk res android  package  com example mylib   gt    After building I get this error  Module  MyApp  was fully rebuilt due to project configuration dependencies changes Compilation completed with 2 errors and 0 warnings in 13 sec 2 errors 0 warnings      MyApp MyLib src main java com example mylib MainActivity java Gradle  package R does not exist Gradle  package R does not exist   Adding dependency doesn t seem to have any impact on the error  Continuing from above   Click File  gt  Project Structure  gt  Modules  gt  MyApp-MyApp Switch to Dependencies Tab Click    gt  Module Dependency and pick MyLib Click Apply and OK Click Build  gt  Make Project   Update 2  Based the suggestions from Ethan this is where we get  The 2 sub project build gradle seem to have all of the correct parts and the only difference is the plugin line bellow is the MyApp build gradle   buildscript       repositories           maven   url  http   repo1 maven org maven2              dependencies           classpath  com android tools build gradle 0 4          apply plugin   android   dependencies       compile files  libs android-support-v4 jar      android       compileSdkVersion 17     buildToolsVersion  17 0 0       defaultConfig           minSdkVersion 7         targetSdkVersion 16           The root project build gradle was empty so I added the two projects like this  dependencies       compile project   MyLib       compile project   MyApp       I now get this error when building  Gradle  FAILURE  Build failed with an exception    Where  Build file   Users kevin GitHub AppPress MyApp build gradle  line  2   What went wrong  A problem occurred evaluating root project  MyApp    gt  Could not find method compile   for arguments  project   MyLib   on root project  MyApp     Try  Run with --stacktrace option to get the stack trace  Run with --info or --debug option to get more log output    Update 3  Big thanks Ethan for solving this    Add compile project   SubProjects MyLib   to the MyLib build gradle Remove compile files  libs android-support-v4 jar   from the MyLib build gradle Close project and Import the root project from gradle   Update 4  As of 0 1 2 you can now include compile  com android support support-v4 13 0 0  instead of compile files  libs android-support-v4 jar    Since it is coming from mavin now you can include this in multiple projects without problems   buildscript       repositories           mavenCentral              dependencies           classpath  com android tools build gradle 0 4 2           apply plugin   android   dependencies       compile  com android support support-v4 13 0 0       compile project   SubProjects MyLib       Update 5  As of 0 1 3 there is now a  Sync Project  button in the toolbar  You can click that instead of reimporting your project after making changes to  gradle files

User · Accepted Answer

Note  This answer is a pure Gradle answer  I use this in IntelliJ on a regular basis but I don t know how the integration is with Android Studio  I am a believer in knowing what is going on for me  so this is how I use Gradle and Android    TL DR Full Example - https   github com ethankhall driving-time-tracker   Disclaimer  This is a project I am was working on   Gradle has a defined structure   that you can change  link at the bottom tells you how   that is very similar to Maven if you have ever used it   Project Root  -- src      -- main  your project           -- java  where your java code goes           -- res   where your res go           -- assets  where your assets go           -- AndroidManifest xml      -- instrumentTest  test project           -- java  where your java code goes   -- build gradle  -- settings gradle   If you only have the one project  the settings gradle file isn t needed  However you want to add more projects  so we need it   Now let s take a peek at that build gradle file  You are going to need this in it  to add the android tools   build gradle  buildscript       repositories           mavenCentral             dependencies           classpath  com android tools build gradle 0 3            Now we need to tell Gradle about some of the Android parts  It s pretty simple  A basic one  that works in most of my cases  looks like the following  I have a comment in this block  it will allow me to specify the version name and code when generating the APK   build gradle  apply plugin   android  android           compileSdkVersion 17                    defaultConfig               versionCode   1             versionName    0 0 0                               Something we are going to want to add  to help out anyone that hasn t seen the light of Gradle yet  a way for them to use the project without installing it   build gradle  task wrapper type  org gradle api tasks wrapper Wrapper        gradleVersion    1 4      So now we have one project to build  Now we are going to add the others  I put them in a directory  maybe call it deps  or subProjects  It doesn t really matter  but you will need to know where you put it  To tell Gradle where the projects are you are going to need to add them to the settings gradle   Directory Structure   Project Root  -- src  see above   -- subProjects  where projects are held       -- reallyCoolProject1  your first included project           -- See project structure for a normal app      -- reallyCoolProject2  your second included project           -- See project structure for a normal app  -- build gradle  -- settings gradle   settings gradle   include   subProjects reallyCoolProject1  include   subProjects reallyCoolProject2    The last thing you should make sure of is the subProjects reallyCoolProject1 build gradle has apply plugin   android-library  instead of apply plugin   android     Like every Gradle project  and Maven  we now need to tell the root project about it s dependency  This can also include any normal Java dependencies that you want   build gradle  dependencies      compile  com fasterxml jackson core jackson-core 2 1 4      compile  com fasterxml jackson core jackson-databind 2 1 4      compile project   subProjects reallyCoolProject1       compile project   subProjects reallyCoolProject2       I know this seems like a lot of steps  but they are pretty easy once you do it once or twice  This way will also allow you to build on a CI server assuming you have the Android SDK installed there   NDK Side Note  If you are going to use the NDK you are going to need something like below  Example build gradle file can be found here  https   gist github com khernyo 4226923  build gradle  task copyNativeLibs type  Copy        from fileTree dir   libs   include        so     into   build native-libs    tasks withType Compile    compileTask - gt  compileTask dependsOn copyNativeLibs    clean dependsOn  cleanCopyNativeLibs   tasks withType com android build gradle tasks PackageApplication    pkgTask - gt    pkgTask jniDir new File  build native-libs       Sources     http   tools android com tech-docs new-build-system user-guide https   gist github com khernyo 4226923 https   github com ethankhall driving-time-tracker

User · Answer

Here is my solution for mac users I think it work for window also   First go to your Android Studio toolbar  Build   Make Project  while you guys are online let it to download the files  and then  Build   Compile Module  your app name is shown here   still online let the files are                                                            download and finish  and then  Run your app that is done it will launch your emulator and configure it then run it   That is it    Happy Coding guys

User · Answer

Gradle Build Tools 2 2 0  - Everything just works  This is the correct way to do it  In trying to avoid experimental and frankly fed up with the NDK and all its hackery I am happy that 2 2 x of the Gradle Build Tools came out and now it just works  The key is the externalNativeBuild and pointing ndkBuild path argument at an Android mk or change ndkBuild to cmake and point the path argument at a CMakeLists txt build script   android       compileSdkVersion 19     buildToolsVersion  25 0 2       defaultConfig           minSdkVersion 19         targetSdkVersion 19          ndk               abiFilters  armeabi    armeabi-v7a    x86                     externalNativeBuild               cmake                   cppFlags  -std c  11                  arguments  -DANDROID TOOLCHAIN clang                            -DANDROID PLATFORM android-19                            -DANDROID STL gnustl static                            -DANDROID ARM NEON TRUE                            -DANDROID CPP FEATURES exceptions rtti                                     externalNativeBuild           cmake                path  src main jni CMakeLists txt                      ndkBuild                path  src main jni Android mk                        For much more detail check Google s page on adding native code   After this is setup correctly you can   gradlew installDebug and off you go  You will also need to be aware that the NDK is moving to clang since gcc is now deprecated in the Android NDK

User · Answer

I just had a very similar issues with gradle builds   adding  jar library  I got it working by a combination of     Moving the libs folder up to the root of the project  same directory as  src    and adding the library to this folder in finder  using Mac OS X  In Android Studio  Right-clicking on the folder to add as library Editing the dependencies in the build gradle file  adding compile fileTree dir   libs   include     jar      BUT more importantly and annoyingly  only hours after I get it working  Android Studio have just released 0 3 7  which claims to have solved a lot of gradle issues such as adding  jar libraries  http   tools android com recent  Hope this helps people

[android] How to build an android library with Android Studio and gradle?

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