Getting a JAR into Android Studio

Brian Marick writes:

I am stunned, as if struck by a ball-peen hammer, by how hard it is to say “use this jar” to Android Studio 1.0.2. If it’s even possible.

It’s certainly possible, and in a standard Android Studio project it is pretty easy. Whether it is the right solution, though, is another matter.

I would recommend that you do some poking around and see if the library is offered as an artifact in some place like Maven Central. The “Gradle, please” Web site can help with this, or you can use the Project Structure dialog in Android Studio itself (File > Project Structure from the main menu). Specifically, the Dependencies tab for your module (e.g., app) has a similar search feature to what “Gradle, please” offers. Just use the + button and choose a “library dependency”, then search.

Whether you find the artifact from “Gradle, please” or add it via the Project Structure dialog, the result is pretty much the same: a compile statement added to your module’s build.gradle file:

dependencies {
    compile 'com.squareup.okhttp:okhttp:2.2.0'
    // and perhaps other lines here

Using the artifact means that chained dependencies (e.g., the JAR depends upon other JARs) are handled for you, and updating to a newer version of the JAR is simply a matter of updating the version number in the compile statement. Plus, your version control system is now tracking what version of the JAR you are using, as opposed to checking in some random JAR binary.

But, suppose you have a random JAR (andataco.jar), and you cannot find an artifact for it.

If your module’s build.gradle file has the standard new-project dependencies closure:

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

then all you need to do is put the JAR in libs/ within the module, and you are done. The compile fileTree() statement says “yo, Gradle, take all the .jar things in libs/ and compile ‘em into the project”. That will add the JAR to the compile-time classpath and, for an Android project, also package the JAR’s contents into your APK file.

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