Android Studio - Importing external Library/Jar

Question

I recently downloaded Android Studio to develop Android applications (I'm coming from Eclipse), and I am having issues using external libraries and/or external JAR files alongside my own project. NOTE: the following tests were conducted on a new application project created from scratch in Android Studio.

Example 1: JAR Import.

1. Download a fresh copy of the Admobs SDK from Google.

2. Copy the library jar GoogleAdMobAdsSdk-6.4.1.jar to the project's /libs/ folder.

3. In the project explorer, right click on the newly added library.jar and click on 'Add as Library'.

Technically at this point everything works, imports work just fine, the layout editor shows a preview of the AdView widget and all that. The only problem is that it doesn't compile successfully.

Log from console:

Gradle: 
FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':APITests:compilePaidDebug'.
> Compilation failed; see the compiler error output for details.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

Could not execute build using Gradle distribution 'http://services.gradle.org/distributions/gradle-1.6-bin.zip'.

I tried running gradlew compileDebug --stacktrace, and the problem seems to be that the despite being able to import the classes successfully in both the code & design editor, at compile time, it cannot resolve the imports. Here's the relevant part of the log: (full stacktrace here)

java:6: error: package com.google.ads does not exist
import com.google.ads.AdRequest;    
java:7: error: package com.google.ads does not exist
import com.google.ads.AdView;
java:11: error: cannot find symbol
AdView mAdView;
symbol:   class AdView
location: class MainActivity
java:22: error: cannot find symbol
mAdView = (AdView)this.findViewById(R.id.adView);
symbol:   class AdView
location: class MainActivity
java:23: error: cannot find symbol
mAdView.loadAd(new AdRequest());
symbol:   class AdRequest
location: class MainActivity
5 errors
:Test:compileDebug FAILED

But again, the imports work well in the editor, and the dependency is there:

It's also worth noting that without attempting to add a library/JAR, the projects compiles just fine.

I then tried editing the build.gradle file to include the new lib like this:

dependencies {
compile files('libs/android-support-v4.jar', 'libs/GoogleAdMobAdsSdk-6.4.1.jar')
}

This time, it did compile successfully, but the app now forces closes, as apparently, it cannot find a specific class from the lib in the application package.

Caused by: java.lang.ClassNotFoundException: Didn't find class "com.google.ads.AdView" on path: /data/app/com.foo.test-1.apk

Any ideas?

Answer 1

So,

Steps to follow in order to import a JAR sucesfully to your project using Android Studio 0.1.1:

• Download the library.jar file and copy it to your /libs/ folder inside your application project.
• Open the build.gradle file and edit your dependencies to include the new .jar file:

compile files('libs/android-support-v4.jar', 'libs/GoogleAdMobAdsSdk-6.4.1.jar')

• File -> Close Project
• Open a command prompt on your project's root location, i.e 'C:\Users\Username\AndroidStudioProjects\MyApplicationProject\'
• On the command prompt, type gradlew clean, wait till it's done.
• Reopen your application project in Android Studio.
• Test run your application and it should work succesfully.