如何在 Android Studio 中添加一个库项目？

Update for Android Studio 1.0

Since Android Studio 1.0 was released (and a lot of versions between v1.0 and one of the firsts from the time of my previous answer) some things has changed.

My description is focused on adding external library project by hand via Gradle files (for better understanding the process). If you want to add a library via Android Studio creator just check the answer below with visual guide (there are some differences between Android Studio 1.0 and those from screenshots, but the process is very similar).

Before you start adding a library to your project by hand, consider adding the external dependency. It won’t mess in your project structure. Almost every well-known Android library is available in a Maven repository and its installation takes only one line of code in the app/build.gradle file:

dependencies {
     compile 'com.jakewharton:butterknife:6.0.0'
}

Adding the library

Here is the full process of adding external Android library to our project:

1. Create a new project via Android Studio creator. I named it HelloWorld.
2. Here is the original project structure created by Android Studio:

HelloWorld/
      app/
           - build.gradle  // local Gradle configuration (for app only)
           ...
      - build.gradle // Global Gradle configuration (for whole project)
      - settings.gradle
      - gradle.properties
      ...

3. In the root directory (HelloWorld/), create new folder: /libs in which we’ll place our external libraries (this step is not required - only for keeping a cleaner project structure).
4. Paste your library in the newly created /libs folder. In this example I used PagerSlidingTabStrip library (just download ZIP from GitHub, rename library directory to „PagerSlidingTabStrip" and copy it). Here is the new structure of our project:

HelloWorld/
      app/
           - build.gradle  // Local Gradle configuration (for app only)
           ...
      libs/
           PagerSlidingTabStrip/
                - build.gradle // Local Gradle configuration (for library only)
      - build.gradle // Global Gradle configuration (for whole project)
      - settings.gradle
      - gradle.properties
      ...

5. Edit settings.gradle by adding your library to include. If you use a custom path like I did, you have also to define the project directory for our library. A whole settings.gradle should look like below:

   include ':app', ':PagerSlidingTabStrip'
   project(':PagerSlidingTabStrip').projectDir = new File('libs/PagerSlidingTabStrip')
   

5.1 If you face "Default Configuration" error, then try this instead of step 5,

    include ':app'
    include ':libs:PagerSlidingTabStrip'

6. In app/build.gradle add our library project as an dependency:

   dependencies {
       compile fileTree(dir: 'libs', include: ['*.jar'])
       compile 'com.android.support:appcompat-v7:21.0.3'
       compile project(":PagerSlidingTabStrip")
   }
   

6.1. If you followed step 5.1, then follow this instead of 6,

    dependencies {
        compile fileTree(dir: 'libs', include: ['*.jar'])
        compile 'com.android.support:appcompat-v7:21.0.3'

        compile project(":libs:PagerSlidingTabStrip")
    }

7. If your library project doesn’t have build.gradle file you have to create it manually. Here is example of that file:

       apply plugin: 'com.android.library'
   
       dependencies {
           compile 'com.android.support:support-v4:21.0.3'
       }
   
       android {
           compileSdkVersion 21
           buildToolsVersion "21.1.2"
   
           defaultConfig {
               minSdkVersion 14
               targetSdkVersion 21
           }
   
           sourceSets {
               main {
                   manifest.srcFile 'AndroidManifest.xml'
                   java.srcDirs = ['src']
                   res.srcDirs = ['res']
               }
           }
       }
   

8. Additionally you can create a global configuration for your project which will contain SDK versions and build tools version for every module to keep consistency. Just edit gradle.properties file and add lines:

   ANDROID_BUILD_MIN_SDK_VERSION=14
   ANDROID_BUILD_TARGET_SDK_VERSION=21
   ANDROID_BUILD_TOOLS_VERSION=21.1.3
   ANDROID_BUILD_SDK_VERSION=21
   

   Now you can use it in your build.gradle files (in app and libraries modules) like below:

   //...
   android {
       compileSdkVersion Integer.parseInt(project.ANDROID_BUILD_SDK_VERSION)
       buildToolsVersion project.ANDROID_BUILD_TOOLS_VERSION
   
       defaultConfig {
           minSdkVersion Integer.parseInt(project.ANDROID_BUILD_MIN_SDK_VERSION)
           targetSdkVersion Integer.parseInt(project.ANDROID_BUILD_TARGET_SDK_VERSION)
       }
   }
   //...
   

9. That’s all. Just click‚ synchronise the project with the Gradle’ icon . Your library should be available in your project.

Google I/O 2013 - The New Android SDK Build System is a great presentation about building Android apps with Gradle Build System: As Xavier Ducrohet said:

Android Studio is all about editing, and debugging and profiling. It's not about building any more.

At the beginning it may be little bit confusing (especially for those, who works with Eclipse and have never seen the ant - like me ;) ), but at the end Gradle gives us some great opportunities and it worth to learn this build system.

Use menu File -> Project Structure -> Modules.

I started using it today. It is a bit different.

For Sherlock, maybe you want to delete their test directory, or add the junit.jar file to the classpath.

To import the library using gradle, you can have to add it to the dependencies section of your build.gradle (the module's one).

E.g.

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.1.0'
    compile 'com.actionbarsherlock:actionbarsherlock:4.4.0@aar'
}

Android Studio is changing.

There exist a section named "Open module settings" if you right-click on a module folder in the project section of Android Studio (I'm using the version 0.2.10).

1. Press F4 to show Project Structure, click libraries or Global libraries, and click + to add the JAR file.
2. Click Modules what you want add jar, select the Dependencies tab, click +, and add Library.

After importing the ABS Module (from File > Project Structure) and making sure it has Android 2.2 and Support Library v4 as dependencies, I was still getting the following error as you @Alex

Error retrieving parent for item: No resource found that matches the given name 'Theme.Sherlock.Light.DarkActionBar'

I added the newly imported module as a dependency to my main app module and that fixed the problem.

If you need access to the resources of a library project (as you do with ABS) ensure that you add the library project/module as a "Module Dependency" instead of a "Library".

To add to the answer: If the IDE doesn't show any error, but when you try to compile, you get something like:

No resource found that matches the given name 'Theme.Sherlock.Light'

Your library project is probably compiled as an application project. To change this, go to:

Menu File -> Project structure -> Facets -> [Library name] -> Check "Library module".

Here is the visual guide:

Update for Android Studio 0.8.2:

In Android Studio 0.8.2, go to Project Structure -> under Modules just hit the plus button and select Import Existing Project and import actionbarsherlock. Then synchronise your Gradle files.

If you face the error

Error: The SDK Build Tools revision (xx.x.x) is too low. Minimum required is yy.y.y

just open the build.gradle file in actionbarsherlock directory and update the buildToolsVersion to the suggested one.

android {
  compileSdkVersion 19
  buildToolsVersion 'yy.y.y'

---

Menu File -> Project Structure...:

Module -> Import Module

After importing the library module, select your project module and add the dependency:

And then select the imported module:

To resolve this problem, you just need to add the abs resource path to your project build file, just like below:

sourceSets {
    main {
        res.srcDirs = ['src/main/res','../../ActionBarSherlock/actionbarsherlock/res']
    }
}

So, I again compile without any errors.

Editing library dependencies through the GUI is not advisable as that doesn't write those changes to your build.gradle file. So your project will not build from the command-line. We should edit the build.gradle file directly as follows.

For instance, given to following structure:

MyProject/

• app/
• libraries/
  • lib1/
  • lib2/

We can identify three projects. Gradle will reference them with the following names:

1. :app
2. :libraries:lib1
3. :libraries:lib2

The :app project is likely to depend on the libraries, and this is done by declaring the following dependencies:

dependencies {
    compile project(':libraries:lib1')
}

I found the solution. It's so simple. Follow froger_mcs instructions.

Make sure that you make the src folder a Source folder in Project Structure -> Modules (Sources).

A simple way to add a JAR file as a library to your Android Studio project:

a) Copy your *.jar files

b) Paste into the libs directory under your projects:

c) Add to build.gradle:

dependencies {
    ...
    compile files('libs/ScanAPIAndroid.jar', 'libs/ScanAPIFactoryAndroid.jar', .., ..)
}

b) If your project from example com.example.MYProject and libraries com.example.ScanAPI has the same namespace com.example, Android Studio will check your build and create all necessary changes in your project. After that you can review these settings in menu File -> Project Structure.

c) If your project and libraries have a different namespace you have to right click on the library and select option "Add as Library" and select the type what you need.

Remember the "Project structure" option is not doing any auto changes in "build.gradle" in the current version of Android Studio (0.2.3). Maybe this feature will be available in the next versions.

I would consider Dependencies, Android Libraries and Multi-project setup necessary reading. Please take a few minutes to do so.

Particularly, in the case of a non-jar library project, read the following snippet from above source:

Gradle projects can also depend on other gradle projects by using a multi-project setup. A multi-project setup usually works by having all the projects as sub folders of a given root project.

For instance, given to following structure:

MyProject/
 + app/
 + libraries/
    + lib1/
    + lib2/

We can identify 3 projects. Gradle will reference them with the following name:

:app
:libraries:lib1
:libraries:lib2

Each projects will have its own build.gradle declaring how it gets built. Additionally, there will be a file called settings.gradle at the root declaring the projects. This gives the following structure:

MyProject/
 | settings.gradle
 + app/
    | build.gradle
 + libraries/
    + lib1/
       | build.gradle
    + lib2/
       | build.gradle

The content of settings.gradle is very simple:

include ':app', ':libraries:lib1', ':libraries:lib2'

This defines which folder is actually a Gradle project.

The :app project is likely to depend on the libraries, and this is done by declaring the following dependencies:

dependencies {
    compile project(':libraries:lib1')
}

Kindly note that there was little or no use of Android Studio GUI to make this happen.

I am currently using git submodules to link the nested library to the actual library git repo to avoid a dependency mess.

If you have Android Studio .0.4.0, you can create a new folder in your build path, YourApp/libraries. Copy the JAR file. There in, right click on it and "Add As Library". Now you have a popup. Just select your directory and press OK, and that's it.

The easiest way I found to include external library project is (for example to include a Facebook library which is stored one directory up in the dependencies folder):

1. In settings.gradle add

   include ':facebook'
   
   project(':facebook').projectDir = new File(settingsDir, '../dependencies/FacebookSDK')
   

2. In build.gradle dependencies section, add

   compile project ('facebook')
   

All left to do is synchronise the project with gradle files.

I had a different cause of the problem so for people:

repositories {
    mavenCentral()
}

change mavenCentral() to jcenter() and add

allprojects {
    repositories {
        jcenter()
    }
}

https://www.dropbox.com/s/1e3eteu3h0pmkf7/Android%20studio%20_doc.doc?dl=0 is the Dropbox link of how to add a JAR file and library project in the latest version of Android Studio 1.0.1.

Please see the documentation with screenshots. It's very easy for a new user.

An example of succesfully adding another library (PullToRefresh). Also works for ABS libproject.

This SO Question

This post

Open the build gradle module app file and add your dependency. If you download the library, just import and build as gradle.

Otherwise add repositories in side gradle module app:

repositories {
        maven { url 'http://clinker.47deg.com/nexus/content/groups/public' }
}

The first repositories will download the library for you.

And compile the downloaded library:

 compile ('com.fortysevendeg.swipelistview:swipelistview:1.0-SNAPSHOT@aar') {
        transitive = true
    }

If you are creating a library, you just need to import the project as import new module.

Indeed as versions are changing, so is changing the user interface and options available on the menu. After reading most of the answers to these questions I had to guess what would work for Android Studio 1.1.0.

1. With your mouse, select the project at the main level (this is where it shows the name of your app).

2. Right click, and select the menu options New, Folder, Assets Folder.

3. After creating the assets folder, paste or copy in it, whatever JAR file you need for your library.

4. From Android Studio's main menu (top of the screen) select File -> Project Structure.

5. Then select your project name and go to the Dependencies tab.

6. Click on the plus sign (+) on the lower left of the dialog box and select file dependency.

7. Finally open the recently created assets folder, select the JAR files that you copied, and then click apply and OK.

Clean and rebuild your project.

Option 1: Drop Files Into Project's libs/directory

The relevant build.gradle file will then update automatically.

Option 2: Modify build.gradle File Manually

Open your build.gradle file and add a new build rule to the dependencies closure. For example, if you wanted to add Google Play Services, your project's dependencies section would look something like this:

dependencies {
     compile fileTree(dir: 'libs', include: ['*.jar'])
     compile 'com.google.android.gms:play-services:6.5.+'
   }

Option 3: Use Android Studio's User Interface

In the Project panel, Control + click the module you want to add the dependency to and select Open Module Settings.

Select the Dependencies tab, followed by the + button in the bottom-left corner. You can choose from the following list of options:

• Library Dependency
• File Dependency
• Module Dependency

You can then enter more information about the dependency you want to add to your project. For example, if you choose Library Dependency, Android Studio displays a list of libraries for you to choose from.

Once you've added your dependency, check your module-level build.gradle file. It should have automatically updated to include the new dependency.

Source

I also encountered the same problem then I did following things.

1. I import the library project into my AndroidStudio IDE as a module using menu File -> Import module menus

2. Then I went to my main module in which I want the library project as a dependent project

3. Right click on the main module (in my case its name is app) -> open module setting -> go into dependencies tab -> click on + button (you will get it on right side of window) -> click on module dependency -> select your library project from list

Apply the changes and click the OK button.

It worked for me. I hope it will help others too.

Simply import the Android library project as a module and in Build.gradle.

Apply plugin: 'com.android.library'

After that, follow these steps:

1. Right click on Module & select open Module settings
2. Select dependencies, click on +, select library dependencies, and add the previously imported module.

I have just found an easier way (rather than writing directly into the .gradle files).

This is for Android Studio 1.1.0.

1. Menu File -> New Module...:

   

   Click on "Import Existing Project".

2. Select the desired library and the desired module.

3. Click finish. Android Studio will import the library into your project. It will sync gradle files.

4. Add the imported module to your project's dependencies.

   Right click on the app folder -> Open Module settings -> go to the dependencies tab -> Click on the '+' button -> click on Module Dependency.

   The library module will be then added to the project's dependencies.

   

5. ???

6. Profit

This is how it works for me in Android Studio 1.5+

In the project where you want to add external library project, go to menu File -> New -> *Import new Module**, navigate to the library project which you want to add to your project, select to add 'library' module in your project. You will get settings.gradle in your projects, beside app, included library, something like this:

include ':app', ':library'

Add in build.gradle(Module :app) in the dependencies section:

Compile project(':library')

Rebuild the project, and that's it.

*You can add as many libraries (modules) as you want. In that case in settings.gradle you will have:

 include ':app', ':lib1', ':lib2', ...

And in build.gradle, you'll need to have:

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])

    // Some other dependencies...

    compile project(':lib1')
    compile project(':lib2')
    ...
}

For Android Studio:

Click on Build.gradle (module: app).

And add for

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    compile files('libs/commons-io-2.4.jar')
}

and in your directory "app", create a directory, "libs". Add the file yourfile.jar:

Finally, compile the Gradle Files:

First Way This is working for MacBook.

First select your builder.gradle file as given screen:

Add dependencies like as on the selected screen:

Select sync project.

If you are getting an error like "Project with path':signature-pad' could not be found in project ':app'", then please use the second way:

Select menu File -> New -> Import Module...:

After clicking on Import Module,

give the path of library like as my MacBook path:

Click on Finish. Now your library are added.

Basically, you can include your JAR files in three different ways. The last one is remote library that is using https://bintray.com/ jcenter online repository. But, if you do it in one of the two other ways, the JAR file will be included physically in your project. Please read this link https://stackoverflow.com/a/35369267/5475941 for more information. In this post I explained how to import your JAR file in Android studio and I explained all possible ways.

In summary, if it is like this (local address), they are downloaded and these JAR files are physically in the project:

But, if it is an internet address like this, they are remote libraries (bintray.com jcenter part) and they will be used remotely:

I hope it helps.

In Android Studio, go to inside app folder, and open build.gradle file. Here you will see dependencies{}. Inside it you can add the library project and synchronise. Now after synchronising the library it will be added to your project, and you can use its functions and classes in your project.

You can do this easily. Go to menu File -> New -> Import Module...:

Browse for the directory which contains the module. Click Finish:

Go to Project Structure and add Module Dependency:

Note: If you receive an SDK error, update that one.

Android Studio 3.0

Just add the library name to the dependencies block of your app's build.gradle file.

dependencies {
    // ...
    implementation 'com.example:some-library:1.0.0'
}

Note that you should use implementation rather than compile now. This is new with Android Studio 3.0. See this Q&A for an explanation of the difference.