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Linking an Android library that is on local machine

I have a set of utils and custom widgets that I want to pull out of my project as an Android library so that I can use them in other projects (and possibly share in the future). I created a new Android Studio project and changed the build.gradle file so that 'com.android.application' was 'com.android.library' and deleted the applicationId. It all compiles fine and I have a .aar file created.
I now want to use this new library as a module in my original project. When I do an Import Project, all the files from the library project are copied into my original project. But I don't want that because if I change the imported library code, it isn't reflected in the library project or vice versa.
I also tried adding this to settings.gradle:
include ':myutils'
project(':myutils').projectDir = new File(settingsDir, '../../../../Development/MyUtils/')
and in the original project app build.gradle:
dependencies {
implementation project(':myutils')
...
But I get this error:
ERROR: Unable to resolve dependency for ':app#debugUnitTest/compileClasspath': Could not resolve project :myutils.
Show Details
Affected Modules: app
How can I link the library to my project without importing it? I would prefer not to go through an external maven repo yet. I'm happy to (and would expect to) recompile my library whenever there is a change there and then rebuild my original project.
Thank you in advance.

I think I just had the same problem - I wanted to put the library .aar file somewhere on my local drive and then use it in a new app as a dependency. I didn't want to have to go through a repo or to include it in the libs folder in the new app. Hopefully that is what the OP asked and the following might be of help to others.
Searching on SO (Aug 2021), majority of answers seemed much more involved than what Android Studio offers (tested on version 4.2). That is, an .aar file that lives outside the app project can now be added as an implementation file in the gradle dependencies. So, it doesn't have to go through a repo, and it doesn't have to be included in the libs folder in the project.
The current documentation (Aug 2021) gives a fairly straightforward answer how to do it:
https://developer.android.com/studio/projects/android-library#psd-add-aar-jar-dependency
In short, if you have put your .aar file somewhere on your local drive, this is how to add it as an implementation file in another app project:
In Android Studio, in your new app project, go to: File > Project Structure > Dependencies.
In: Modules > app > Declared Dependencies, click '+' and select 'Jar Dependency'. (Even though you are trying to use an .aar file, you still select 'Jar Dependency').
In the 'Add Jar/Aar Dependency' popup dialog:
in step 1 enter the path to your .aar file on your local drive, and
in step 2 select 'implementation'.
If everything worked out, your build.gradle(Module) should have a line in the dependencies that looks like:
dependencies {
implementation files('../../../MyFolder/MyLibraryFile.aar')
A few notes:
You can actually just add the dependency manually, by typing it into the build.gradle(Module) dependencies, so you don't actually have to go through the Android Studio dialog outlined above.
you can either use a relative path (as the example above), or an absolute path.
the Android Studio dialog is somewhat limited in that you cannot just browse to your file (in point 3, step 1), but you have to actually enter the path manually.
Probably the most important: Whenever you make a change in the library and assemble a new .aar file, then remember to do the following in your app project that uses the .aar file as a dependency: Clean Project, then Sync Project with Gradle Files, and only then run the app, so that the changes in the library could take effect in your app.

I have been using Phgr's above technique for four years. I have three comments -
First, I don't clean the app project each time I change the library - I just do a Sync Project before building and testing the app.
Second, I changed the File-Settings-Keymap-Main Menu-File-Sync to Alt-S for easy of syncing - I hate wasting time using the mouse for selecting the Sync icon.
Third, I have an implementation line in the app's build module file for each app variant such as the following -
debugImplementation files('c:/Android Studio Projects/PciLibrary/app/build/outputs/aar/PciLibrary-debug.aar')
releaseImplementation files('c:/Android Studio Projects/PciLibrary/app/build/outputs/aar/PciLibrary-release.aar')
All of this is working fine with Android Studio 4.2.2 and sdk version 30.
Hope this helps others with this problem

Create a standalone library module in Android studio

Creating a standalone library application is a common task in Eclipse + ADT.
I thought that this should be a simple task in Android Studio (1.2 or above), but after struggling with this problem for two days, I figured out that google did nothing about this and implementing a standalone library module is not as simple as I thought. So I decided to share my experiences with you.

To create a standalone and reusable library module in Android Studio:
1- Create a new project with no Activity.
2- New project's default module is named app. Right click on module and refactor/rename it to something like 'library'. Close Android Studio.
3- Open file explorer and rename module's folder from app to library.
4- Open .idea folder. There are some XML files there that have references to app folder. Replace app into library in these files.
5- Open module's gradle file (library/build.gradle) and change plugin to com.android.library. Then remove applicationId.
6- Open Android Studio. Rebuild module. If there is no error, we are done here.
7- Open application which is dependent on that module. Open settings.gradle and include library module as below:
include ':library'
project(':library').projectDir = new File('/Path/To/LibraryProject/library')
8- Open application's app module build.gradle file and add this line into dependencies section:
compile project(':library')
9- Rebuild your project. If everything is right, you will see library module in your project. You can edit library module from there and/or its project and more important: Now you have a standalone library module that you can reuse in multiple projects!
I hope google will make this process a lot easier in future releases of Android Studio!
EDIT:
I checked Android Studio version 1.4 and hopefully in this version we can omit steps 3 and 4.

How to import a library project in Android Studio, without making a copy?

OK I know people have asked this problem thousands times, but Android studio is so so so hard to understand and use and I still can't find the correct way.
I find several solutions, but all of them says to copy the library codes into main project. It makes no sense to me. When I try to build a standalone project for the library, I find no "New project from existing source" like that in Eclipse.
Can I have a step-to-step for:
I have a main Android Studio project
I have an Eclipse Android library project
Without making a copy of library project
I can let the main project "use" library project
The point is, if I have many app projects using the same library source, I can just modify one copy. If I need to put library codes in every app project, it's a disaster. Eclipse can do this without any problem.
Thank you. I'm really exhausted with Android Studio, but I can't choose to stay on Eclipse since Google says ADT won't be supported anymore.

The real answer to keep your library project only in one place is in this post :
Android Studio 0.8.1 Creating Modules without copying files?

In Android Studio Project import your eclipse library project as new module. Then in Android studio right click on your app module go to module setting > select dependency tab > click plus> select module dependency > select library project module.

new Module or import Module under the project，
then open Module Settings--》Module dependencies --》‘+’ module dependencie.

Importing eclipse android project into android studio

I am trying to import an android project created in eclipse into android studio. This main project also refers to another library project in the same eclipse workspace. The folder structure is like this:
workspace\app1
workspace\lib1
When I import the main project into android studio, the library project is automatically imported as a sub-project (or shall we call it a module) within the main project. That's not what I want. The library project is shared by multiple apps I am maintaining. It should sit in parallel with other app projects in terms of folder structure. I wouldn't want it to go understand any particular app project.
Please help explain how I can make the library project stand its own and refer to the library project from other app projects in android project. I am fairly new to the gradle build system. So detailed instructions would be highly appreciated. Thanks a lot!

Since you are importing in android studio, I assume you are moving to gradle build system. In your case , I think, it would be best to have a separate AS project for library. Use that project to generate a jar file and then import that jar using gradle build script in each project you want to use it.

If you are sharing the same library across multiple, you can configure them as separate AS project and have "aar" file as output. (In your gradle you put>> apply plugin: 'android-library'). You then define them as dependency in your gradle file. (either through maven repo or putting it in your libs directory and defining it in your dependencies section). You can find more info at http://tools.android.com/tech-docs/new-build-system/user-guide#TOC-Library-projects

You can use version control tool such as git to synchronize the library project in every main project. But you need to use a version control tool to manage all your projects first.

Read here on "AS Modules"
review 57.1.2 on "common behavior"
Take a look at a project built on AS pattern of modules as libs used in eclipse (gradle.settings) pictured
all the includes are modules
maybe you can rethink the idea of how to get AS to work for you in reusing code....

Eclipse -> Android Studio migration: how to include v4 support library (also including the ant build script)

I have a setup of android project on eclipse and I want to migrate to Android Studio. So, I have android-support-v4.jar that I use for my main project and my Facebook lib-project.
I guess I have to exclude lib-projects as a folder in my main module (lets call the main module Jack). Jack has dependancy on the facebook lib-project.
How should I define the android-support-v4.jar as a separate library and use it in both projects? Or should I just use directly the jar files and leave them in both Jack's libs folder and Facebook libs folder?
If the first option should be done, will ant clean release still work (with the build.xml android generated file)?

In Android Studio, builds are done with Gradle now. Gradle is different. With gradle, you tell your project which jar's you need, and it will connect to a server and download them if it doesn't already have them when you compile your apk.
A few things to note:
When you install Android Studio, it has it's own Android sdk directory. You have to download everything from the sdk downloader (from inside the Android Studio App) again. Don't bother trying to switch the sdk download path to your current one. You will only encounter bugs (Or at least I did).
So your question is worded very confusingly. It sounds like you have a main module, and then you have a library module, and the library module uses the support library.
You'll need to set it up so the main module has a dependency on your library module. From there, you'll need to go into your library module's gradle file and tell it that you want to include the android support library
dependencies {
compile 'com.android.support:appcompat-v7:19.0.0'
}
The support library is a little weird in gradle. Gradle normally would download the dependencies you need. However, android studio requires that you have the support library installed through their sdk downloader (top-right group of icons in android studio. The download icon).
After you get all your dependencies entered into your gradle file, you'll then need to go to Tools -> Android -> Sync gradle files with project. From there compile errors should go away, and you should be able to run the project.
Best of luck. By the way, Here is the documentation on Gradle on the android website. I find myself having to go to it A LOT, especially when I made the switch from Eclipse to Android Studio. This + Various tutorials I found as needed via google. http://tools.android.com/tech-docs/new-build-system/user-guide
EDIT: This link might also be helpful. Google has some steps for switching from eclipse to Android Studio: http://developer.android.com/sdk/installing/migrate.html That with some of the stuff above may prove helpful.

While I haven't tried this myself, I suggest you use the recommended migration steps provided by Google in this article.
Before you do that, though, make sure that you either:
Check that both support libraries on the main project and dependencies have the same version (Eclipse will complain about it during build time, and will likely cause problems during conversion to Gradle script.); OR,
Uncheck the "Android Private Libraries" entry on the Order and Export tab of the dependency project's build settings.
If the migration process described doesn't work smoothly for you, you can always call the Ant build script from within the Gradle script, as described here.

The Android Studio uses only Gradle, but you can export Android ant project from eclipse.
To do that go to File -> import project usually next, next, next... works.
If not go to project setting Shift + Ctrl + Alt + S and under modules -> PROJECT_NAME -> Dependencies you can add your support library.
To add a Facebook library you must add it as another module to your project.
If you still want to use Ant there is another option: Use Intellij IDEA which support Ant.