Sometimes we use third-party library, or we implements a module and want it to be a part of our main code’s library. In both scenarios, we can import a library as a module.

How to import a library in Android Studio?

  1. File > New > Import modlue > add the library path.
  2. Change library module gradle:
    1. Change “apply plugin: ‘com.android.application’” to “apply plugin: ‘com.android.library’”
    2. Remove applicationId.
  1. Change dependency from “compile” to “implementation”
  2. File > Project Structure > app > Dependencies, add module library.
  3. Downgrade gradle version in project gradle to “2.3.3” or “2.3.2”
  4. Put/Change “buildToolsVersion “27.0.1” and “useLibrary ‘org.apache.http.legacy’” in app and carto library module.

UnsatisfiedLinkError happens?

This is because no .so file in the app to let the app know there is a new library added. There are several steps involved to add up .so file.

  1. Go to Project view.
  2. Copy library directory, move it under app > libs. Now you are able to see .so files.
  3. Copy jni directory under app > src > main.
  4. Change name of this directory from jni to jniLibs.
  5. Delete no longer using library directory in app > libs.

Now .so file exists in the app in a correct directory.
Then open mainAcitivity add those lines in the class:

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static {         
    System.loadLibrary("library"); 
}

How to Run?

Since we added a library as a module, therefore, our compile will ask us to edit configuration. To avoid that, go back to MainActivity and run MainActivity instead.

Import library by .aar file

It is much more easy than import a library by moudle. Some library provide .aar file, we can simply import it by those following steps:

  1. add flatDir {dirs 'libs' } in the project level build.gradle under allprojects { repositories { ... } } level.

  2. copy .aar file that you want to import under the app’s libs directory.

  3. add implementation(name: 'XXX', ext: 'aar') in the app level build.gradle under dependencies level.