Remember that Android Studio uses Gradle as a build tool, and part of the build flow is to handle dependencies. That being said, you have to specify to Gradle that includes your external jar files, making the following modifications:
- Open
build.gradle
file of your module project (generally called "app")
- Inside "dependencies", add
compile fileTree(dir: 'libs', include: ['*.jar'])
- Create a folder called
libs
inside your module app.
- Copy your jar file inside of it
Run the build process of Gradle clicking in the "Sync now" link of Android Studio, and now your library should be recognized.