How to embed an Android library (AAR file) into a capacitor plugin?

Question

The issue is already answered for iOS: How to embed framework in capacitor plugin for iOS

For Android, I get issues when I add an aar file to the capacitor plugin by

Answer 1

As done on iOs, we do practically the same thing here. But, using Android Studio and gradle instead of xcode and cocoapods. Ok, but first things first.

When the command npx @capacitor/cli plugin:generate is issued, what the CLI does is to start a folder containing a cocoa pod for iOs and a gradle plugin for Android. You can see this on the image below.

With the above command issued, there will be a ios and android folders inside you generated plugin folder. If this checks, open you android studio and select the option to open a android studio project, selecting the android folder to fulfil this procedure. You can select this option on the initial screen, like showed on the next image.

With the project opened, if all went well you'll se your android studio showing a screen like this

Now, lets add the plugin files. To do this, right click the android java module and select the "Open Module settings" option, as shown on the next image.

With the following screen opened, we need to add a module here that contains our jar/aar dependencies. To do that, just click on the + sign that is showed above.

On the new module screen, if you scroll down there will be a "Import .JAR/.AAR package", like shown above.

After that, locate you aar package. The result will be the following.

Click finish and the next screen will appear. If not, hit the apply button in this same screen.

Since my module has a dependency, I'll repeat this part of the tutorial.

Next, we need to add our recently added modules as dependencies of the android module. On the same screen, click on the dependencies option and on the plus sign of the "declared dependencies" pane.

The following screen will show. We need to select the 3rd option, since what we did early was adding a module.

Now, lets select our module. Its simple, just mark it and click ok. Since I have to, as said before, I'll check both of them.

If this step went well, you should have now you android module with one more dependency (or two in my case). The image bellow show that.

Hit apply and close this window. Gradle will rebuild your plugin project on the background and after that,since I know kotlin better, I'll convert my project to kotlin. If you wish, this can be done as shown on the next image, but is not mandatory.

With all the above done correctly, you can now import your lib on the TestPlugin.kt (or .java if you didnt use kotlin). For reference, the image bellow show the minimum implementation for my plugin.

In the plugin folder, we are done. Pack it using npm and install on you app.

Next, to the plugin works properly, we need to add its class on the MainActivity of the app that you'll be using it.

Now, to make it work, i'm not 100% sure that this is the correct way to do it, but since it works I do this way. The way I do is to add the plugin modules on the android module of the app via script. I think i am missing something on the gradle plugin implementation, but since it works.....

To do this, access, on your app, the android/settings.gradle file and append this:

Please note that depending on the changes that you do, the settings.gradle file will be rewritten. Do a script to keep the info always there or check it before build.

Thats it, please comment if you know another way to this next step or in any another if there is a better approach. And, if this answer is useful, please thumbs it up, since this implementation, when finished and working, made me cry a little (of happiness, of course).